JP6752871B2 - Motor control device, sheet transfer device, document feeding device, document reading device and image forming device - Google Patents

Description

The present invention is a motor controller for controlling the drive current flowing through the windings of the motor, the sheet conveying device, a document feeder, to a document reading apparatus及beauty picture image forming apparatus.

Conventionally, as a method of controlling a motor, a control method called vector control is known in which the motor is controlled by controlling a current value in a rotating coordinate system based on the rotation phase of the rotor of the motor. Specifically, for example, the motor is controlled by performing phase feedback control that controls the current value so that the deviation between the command phase of the rotor and the actual rotation phase becomes small. There is also a method of controlling the motor by performing speed feedback control for controlling the current value so that the deviation between the command speed of the rotor and the actual rotation speed becomes small.

When vector control is used, the drive current supplied to the windings of the motor is the current component (q-axis current) that generates torque for the rotor to rotate, and the current component (d-axis) that affects the magnetic flux strength of the rotor. It can be controlled separately from the current). As a result, even if the load torque applied to the rotor changes, the torque required for rotation can be efficiently generated by controlling the q-axis current according to the change in the load torque. That is, an uncontrollable state (step-out state) in which the load torque applied to the rotor exceeds the output torque corresponding to the drive current supplied to the winding of the motor, which has been a problem in the past, and the rotor is not synchronized with the input signal. ) Can be prevented. In addition, it is possible to suppress an increase in power consumption and an increase in motor noise due to excess torque.

Vector control requires a configuration that determines the phase of the rotor. In Patent Document 1, the current value of the drive current flowing through the windings of each phase of the motor is detected, and the induced voltage generated in the windings of each phase of the motor is determined (calculated) based on the detection result. A method is described in which the phase of the rotor is determined based on the induced voltage generated in the winding of each phase, and the drive of the motor is controlled based on the phase determination result.

The detected current value includes a harmonic component of the fundamental frequency of the electric angle of the motor. Patent Document 2 describes a configuration in which a low-pass filter for reducing a signal having a frequency higher than a predetermined frequency (cutoff frequency) is provided in a motor drive device, and the harmonic component is reduced by using the low-pass filter. Has been done.

Further, Patent Document 3 describes a configuration in which the cutoff frequency is changed according to the rotation speed of the motor.

Special Table 2012-509056 Japanese Unexamined Patent Publication No. 2014-103841 JP-A-2008-193869

When a low-pass filter composed of a digital filter is used to reduce a signal (noise) of a harmonic component, the frequency band in which the low-pass filter can be reduced differs depending on the order of the filter. Specifically, the higher the order of the filter, the more the signal in the low frequency band can be reduced.

Further, the frequency of the harmonic component differs depending on the rotation speed of the rotor of the motor. Specifically, the slower the rotation speed of the rotor, the lower the frequency of the harmonic component. Therefore, the frequency of the harmonic component changes by changing the rotation speed of the rotor, and there is a possibility that the signal of the harmonic component cannot be reduced by the filter of the preset order. Specifically, for example, if the rotation speed of the rotor is slowed down, there is a possibility that the signal of the harmonic component cannot be reduced by the filter of the preset order.

The frequency of the harmonic component also differs depending on the type of motor. Therefore, when different types of motors are installed by replacing the motors, it may not be possible to reduce the signal of the harmonic component with a preset order filter. Specifically, for example, when the frequency of the harmonic component included in the detection current of the motor after replacement is lower than the frequency of the harmonic component contained in the detection current of the motor before replacement, it is preset. It may not be possible to reduce noise with a filter of the same order. If the phase of the rotor is determined based on the current value in which the signal of the harmonic component is not reduced and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

In these cases, it is conceivable to increase the order of the filter, etc. ho order filters is large, the amount of memory such as RAM is increased, as a result, cost increases.

In view of the above problems, the present invention is, while suppressing an increase in cost, and an object thereof is to reduce the harmonic NamiNaru component contained in the detected driving current.

In order to solve the above problems , the motor control device according to the present invention is
In a motor control device that controls a drive current flowing through a winding of the motor based on a command phase representing a target phase of the rotor of the motor.
An acquisition means for acquiring the current value of the drive current flowing through the winding at a predetermined cycle, and
A filter circuit that reduces the harmonic component of the fundamental frequency of the drive current included in the signal represented by the current value acquired by the acquisition means, and
A phase determining means for determining the rotational phase of the rotor based on the signal after the filter processing by the filter circuit is applied, and
A control means for controlling the drive current flowing through the winding so that the deviation between the command phase and the rotation phase determined by the phase determining means becomes small.
Have,
The filter circuit is characterized in that the harmonic component is reduced based on a number of current values less than the number of current values that can be acquired by the acquisition means within a period of one cycle of the harmonic component .

According to the present invention, it is possible to reduce the harmonic component included in the detected drive current while suppressing the increase in cost.

It is sectional drawing explaining the image forming apparatus which concerns on 1st Embodiment. It is a block diagram which shows the control structure of the image forming apparatus. It is a block diagram which shows the structure of the motor control device which concerns on 1st Embodiment. It is a figure which shows the relationship between the two-phase motor which consists of A phase and B phase, and d-axis and q-axis of a rotating coordinate system. It is a block diagram which shows the structure of the motor control device which performs speed feedback control. It is a block diagram which shows the structure of the low-pass filter which concerns on 1st Embodiment. It is a figure which shows the signal of the primary component and the 3rd component of the electric angular frequency which concerns on 1st Embodiment, and is the figure which shows the induced voltage determined based on the signal, and the electric angle determined based on the induced voltage. .. It is a figure explaining the method which the thinning-out controller thins out the data of a current value and a voltage value. It is a flowchart which shows the method which the motor control device determines the thinning rate. It is a block diagram which shows the structure of the motor control device which concerns on 2nd Embodiment. It is a figure which shows the waveform of the current acquired by the current value acquirer which concerns on 2nd Embodiment. It is a flowchart which shows the method which the motor control device determines the thinning rate. It is a block diagram which shows the structure of the motor control device which concerns on 3rd Embodiment.

Preferred embodiments of the present invention will be described below with reference to the drawings. However, such components shape and their relative arrangement that is described in this embodiment, should be appropriately modified by the configuration and various conditions of an apparatus to which the present invention is applied, the scope of the invention It not intended that will be limited to the following embodiments. In the following description, the case where the motor control device is provided in the image forming device will be described, but the case where the motor control device is provided is not limited to the image forming device. For example, it is also used in a sheet transfer device for transporting a sheet such as a recording medium or a document.

[First Embodiment]
[Image forming device]
Figure 1 is an electrophotographic copying machine of monochrome having the sheet conveying device is found used in the present embodiment (hereinafter, referred to as an image forming apparatus) is a sectional view showing a 100 configuration. The image forming apparatus is not limited to the copying machine, and may be, for example, a facsimile apparatus, a printing machine, a printer, or the like. Further, the recording method is not limited to the electrophotographic method, and may be, for example, an inkjet or the like. Further, the format of the image forming apparatus may be either monochrome or color.

The configuration and function of the image forming apparatus 100 will be described below with reference to FIG. As shown in FIG. 1, the image forming apparatus 10 0 includes a document feeding OkuSo location 201, read winding device 202 and the image printing equipment 3 01.

Originals stacked on the original stacking portion 203 of the document feeder 201 is fed one by one by the feed roller 204, is conveyed onto the original glass stand 214 of the read winding device 202 along a conveyance guide 206. Further, the original document is conveyed at a constant speed by the conveying belt 208, and is ejected by the paper ejection roller 205 to an output tray (not shown) . Light reflected from the illuminated document image by the illumination 209 at the reading position of the reading winding device 202 is guided to the image reading section 1 1 1 by an optical system consisting of the reflecting mirror 210, 211 and 212, the image reading unit 1 1 1 Is converted into an image signal. The image reading unit 1 1 1 is composed of a lens, a CCD which is a photoelectric conversion element, a driving circuit of the CCD, and the like. Image signal output from the image reading unit 1 1 1, after each seed correction processing is performed by the image processing unit 112 composed of a hardware device such as an ASIC, is output to the image printing equipment 3 01 To. As described above, the original is read. That is, the document feeding device 201 and the reading device 202 function as the document reading device.

Further, as a document reading mode in the reading device 202, there are a scanning mode and a fixed reading mode. The scanning mode is a mode in which an image of a document is read while the document is conveyed at a constant speed with the illumination system 209 and the optical system fixed at predetermined positions. The fixed reading mode is a mode in which the original is placed on the original glass 214 of the reading device 202, and the image of the original placed on the original glass 214 is read while moving the illumination system 209 and the optical system at a constant speed. is there. Normally, sheet-shaped originals are read in the scanning mode, and bound originals such as books and booklets are read in the fixed reading mode.

Inside the image printing equipment 3 01, the sheet storage trays 302, 304 are provided. Different types of recording media can be stored in the sheet storage trays 302 and 304. For example, the sheet storage tray 302 stores A4 size plain paper, and the sheet storage tray 304 stores A4 size thick paper. The recording medium is one in which an image is formed by an image forming apparatus, and for example, paper, a resin sheet, a cloth, an OHP sheet, a label, and the like are included in the recording medium .

The recording medium stored in the sheet storage tray 302 is fed by the paper feed roller 303 and sent out to the registration roller 308 by the transport roller 306. Further, the recording medium stored in the sheet storage tray 304 is fed by the paper feed roller 305 and sent out to the registration roller 308 by the transport rollers 307 and 306.

The image signal output from the reading device 202 is input to the optical scanning device 311 including the semiconductor laser and the polygon mirror. Further, the outer peripheral surface of the photosensitive drum 309 is charged by the charger 310. After the outer peripheral surface of the photosensitive drum 309 is charged, the laser beam corresponding to the image signal input from the reading device 202 to the optical scanning device 311 is photosensitiveed from the optical scanning device 311 via the polygon mirror and the mirrors 312 and 313. The outer peripheral surface of the drum 309 is irradiated. As a result, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 309. For charging the photosensitive drum, for example, a charging method using a corona charger or a charging roller is used.

Subsequently, the electrostatic latent image is developed by the toner in the developer 314, and the toner image is formed on the outer peripheral surface of the photosensitive drum 309. The toner image formed on the photosensitive drum 309 is transferred to the recording medium by a transfer separator 315 provided at a position (transfer position) facing the photosensitive drum 309. At this time, the registration roller 308 feeds the recording medium to the transfer position in time with the toner image.

As described above, the recording medium on which the toner image is transferred is sent to the fixing device 318 by the transport belt 317, heated and pressurized by the fixing device 318, and the toner image is fixed on the recording medium. In this way, the image forming apparatus 100 forms an image on the recording medium.

When image formation is performed in the single-sided printing mode, the recording medium that has passed through the fixing device 318 is ejected to an output tray (not shown) by the output rollers 319 and 324. When image formation is performed in the double-sided printing mode, the recording medium is a paper ejection roller 319, a transport roller 320, and an inversion roller 321 after the fixing process is performed on the first surface of the recording medium by the fixing device 318. Is transported to the reverse path 325. After that, the recording medium is conveyed to the registration roller 308 again by the conveying rollers 322 and 323, and an image is formed on the second surface of the recording medium by the method described above. After that, the recording medium is ejected to an output tray (not shown) by the output rollers 319 and 324.

When the recording medium on which the image is formed on the first surface is discharged face-down to the outside of the image forming apparatus 100, the recording medium that has passed through the fixing device 318 is passed through the paper ejection roller 319 to the transfer roller 320. Transport in the direction you are heading. Then, just before the rear end of the recording medium passes through the nip portion of the transport roller 320, the rotation of the transport roller 320 is reversed. As a result, the recording medium is discharged to the outside of the image forming apparatus 100 via the paper ejection roller 324 with the first surface of the recording medium facing downward.

The above is a description of the configuration and function of the image forming apparatus 100. The load in the present invention is an object driven by a motor. For example, various rollers (conveying rollers) such as paper feed rollers 204, 303, 305, registration rollers 308 and paper ejection rollers 319, photosensitive drums 309, transport belts 208, 317, lighting systems 209, optical systems and the like are in the present invention. Corresponds to the load. The motor control device of the present embodiment can be applied to a motor that drives these loads.

FIG. 2 is a block diagram showing an example of a control configuration of the image forming apparatus 100. As shown in FIG. 2, the system controller 151 includes a CPU 151a, a ROM 151b, and a RAM 151c. Further, the system controller 151 is connected to an image processing unit 112, an operation unit 152, an analog / digital (A / D) converter 153, a high voltage control unit 155, a motor control device 157, sensors 159, and an AC driver 160. .. The system controller 151 can send and receive data and commands to and from each connected unit.

The CPU 151a executes various sequences related to a predetermined image formation sequence by reading and executing various programs stored in the ROM 151b.

The RAM 151c is a storage device. The RAM 151c stores, for example, various data such as a set value for the high-voltage control unit 155, a command value for the motor control device 157, and information received from the operation unit 152.

The system controller 151 transmits to the image processing unit 112 the setting value data of various devices provided inside the image forming device 100, which is necessary for the image processing in the image processing unit 112. Further, the system controller 151 receives signals from various devices (signals from sensors 159 and the like), and sets a set value of the high voltage control unit 155 based on the received signals. The high-voltage control unit 155 supplies the necessary voltage to the high-voltage unit 156 (charger 310, developer 314, transfer separator 315, etc.) according to the set value set by the system controller 151. The sensors 159 include sensors and the like that detect the recording medium conveyed by the transfer roller.

The motor control device 157 controls the motor 509 that drives the above-mentioned load in response to a command output from the CPU 151a.

The A / D converter 153 receives the detection signal detected by the thermistor 154 for detecting the temperature of the fixing heater 161, converts the detection signal from an analog signal to a digital signal, and transmits the detection signal to the system controller 151. The system controller 151 controls the AC driver 160 based on the digital signal received from the A / D converter 153. The AC driver 160 controls the fixing heater 161 so that the temperature of the fixing heater 161 becomes a temperature required for performing the fixing process. The fixing heater 161 is a heater used for the fixing process, and is included in the fixing device 318.

The system controller 151 displays the operation screen for the user to set the type of recording medium to be used (hereinafter referred to as paper type) on the display unit provided in the operation unit 152. To control. The system controller 151 receives the information set by the user from the operation unit 152, and controls the operation sequence of the image forming apparatus 100 based on the information set by the user. Further, the system controller 151 transmits information indicating the state of the image forming apparatus to the operation unit 152. The information indicating the state of the image forming apparatus is, for example, information such as the number of images formed, whether or not an image is being formed, jam occurrence and its occurrence location. The operation unit 152 displays the information received from the system controller 151 on the display unit.

As described above, the system controller 151 controls the operation sequence of the image forming apparatus 100.

[Vector control]
Next, the motor control device in this embodiment will be described. The motor control device in the present embodiment controls the motor by using vector control. In the following description, a stepping motor is used as the motor for driving the load, but the present invention is not limited to this. Further, the motor is not always a two-phase motor. Further, it is assumed that the motor in the present embodiment is not provided with a sensor such as a rotary encoder for detecting the rotation phase of the rotor of the motor.

FIG. 3 is a block diagram showing an example of the configuration of a motor control device 157 that controls a stepping motor (hereinafter, referred to as a motor) 509.

First, a method in which the motor control device 157 in this embodiment performs vector control will be described with reference to FIGS. 3 and 4.

FIG. 4 is a diagram showing the relationship between the motor 509 composed of two phases, A phase (first phase) and B phase (second phase), and the d-axis and q-axis of the rotating coordinate system. In FIG. 4, in the stationary coordinate system, the axis corresponding to the A-phase winding is defined as the α-axis, and the axis corresponding to the B-phase winding is defined as the β-axis. Further, the angle formed by the α-axis in the stationary coordinate system and the direction of the magnetic flux (d-axis direction) created by the magnetic poles of the permanent magnet used in the rotor 402 is defined as θ. The rotation phase of the rotor 402 is represented by an angle θ. In vector control, the motor 509 is represented by a d-axis along the magnetic flux direction of the rotor 402 and a q-axis along a direction 90 degrees counterclockwise from the d-axis (perpendicular to the d-axis). A rotation coordinate system based on the rotation phase θ of the rotor 402 is used.

Vector control is a control method for controlling a motor by controlling a current value in a rotating coordinate system based on the rotation phase of the rotor of the motor. Specifically, for example, the motor is controlled by performing phase feedback control that controls the current value so that the deviation between the command phase representing the target phase of the rotor and the actual rotation phase becomes small. There is also a method of controlling the motor by performing speed feedback control for controlling the current value so that the deviation between the command speed representing the target speed of the rotor and the actual rotation speed becomes small. The current value in the rotation coordinate system is the current value of the q-axis component (torque current component) that generates torque in the rotor of the motor and the d-axis component (excitation current component) that affects the magnetic flux strength of the rotor of the motor. Corresponds to the current value.

The motor control device 157 includes a phase controller 502, a current controller 503, a coordinate inverse converter 505, a coordinate converter 511, a PWM inverter 506 that supplies a drive current to the winding of the motor, and the like as circuits for performing vector control. It is provided. The coordinate converter 511 expresses the current vector corresponding to the drive current flowing through the windings of the A phase and the B phase of the motor 509 from the stationary coordinate system represented by the α axis and the β axis by the q axis and the d axis. Coordinates are converted to the rotating coordinate system. As a result, the drive current supplied to the A-phase and B-phase windings of the motor 509 is set to the current value of the q-axis component (q-axis current) and the current value of the d-axis component (d-axis current) in the rotating coordinate system. Can be expressed using. The q-axis current corresponds to the torque current that generates torque in the rotor 402 of the motor 509. Further, the d-axis current corresponds to an exciting current that affects the magnetic flux strength of the rotor 402 of the motor 509, and does not contribute to the generation of torque of the rotor 402. The motor control device 157 can independently control the q-axis current and the d-axis current. That is, the torque required for the rotor 402 to rotate can be efficiently generated.

The motor control device 157 determines the rotation phase θ of the rotor 402 of the motor 509 by a method described later, and performs vector control based on the determination result. The CPU 151a generates a command phase θ_ref representing the target phase of the rotor 402 of the motor 509, and outputs the command phase θ_ref to the motor control device 157 at a predetermined time cycle.

The adder 101 calculates the deviation between the rotation phase θ of the rotor 402 of the motor 509 and the command phase θ_ref, and outputs the deviation to the phase controller 502.

The phase controller 502 is composed of a proportional (P) and integral (I) compensator. The phase controller 502 uses a proportional (P) and integral (I) compensator to generate a q-axis current command value iq_ref and a d-axis current command value id_ref so that the deviation output from the adder 101 is small. And output. Specifically, the phase controller 502 uses the proportional (P) and integral (I) compensators, and the q-axis current command value iq_ref and the d-axis so that the deviation output from the adder 101 becomes 0. Generates and outputs the current command value id_ref. The phase controller 502 in the present embodiment is composed of the proportional (P) and integral (I) compensators, but is composed of the proportional (P), integral (I) and differential (D) compensators. You may. When a permanent magnet is used for the rotor 402, the d-axis current command value id_ref, which normally affects the magnetic flux strength of the rotor 402, is set to 0, but the present invention is not limited to this.

The drive currents flowing through the A-phase and B-phase windings of the motor 509 are detected by the current detectors 507 and 508, and then converted from analog values to digital values by the A / D converter 510.

The current value acquirer 516 acquires the current value of the drive current converted from the analog value to the digital value by the A / D converter 510 at a predetermined cycle. The current value acquired by the current value acquirer 516 is expressed by the following equation as the current values iα and iβ in the stationary coordinate system using the phase θe of the current vector shown in FIG. The phase θe of the current vector is defined as the angle formed by the α axis and the current vector.

iα = I * cosθe (1)
iβ = I * sinθe (2)
These current values iα and iβ are input to the coordinate converter 511 and the thinning controller 519.

In the coordinate converter 511, the current values iα and iβ are coordinate-converted into the current value iq of the q-axis current and the current value id of the d-axis current in the rotating coordinate system by the following equation.

id = cosθ * iα + sinθ * iβ (3)
iq = −sinθ * iα + cosθ * iβ (4)
As described above, the coordinate converter 511 transfers the current vector corresponding to the drive current flowing through the A-phase and B-phase windings of the motor 509 from the stationary coordinate system represented by the α-axis and the β-axis to the q-axis and the q-axis. Coordinates are converted to a rotating coordinate system represented by the d-axis.

The adder 102 calculates the deviation between the iq_ref output from the phase controller 502 and the current value iq output from the coordinate converter 511, and outputs the deviation to the current controller 503. Further, the adder 103 calculates the deviation between the id_ref output from the phase controller 502 and the current value id output from the coordinate converter 511, and outputs the deviation to the current controller 503.

The current controller 503 is composed of a proportional (P) and integral (I) compensator. The current controller 503 generates the current values iq * and id * so that the deviations become smaller, respectively. Specifically, the current controller 503 generates the current values iq * and id * so that the deviations become 0, respectively. After that, the current controller 503 generates drive voltages Vq and Vd corresponding to the respective current values iq * and id * and outputs them to the coordinate inverse converter 505. That is, the current controller 503 functions as a voltage generating means. The current controller 503 in the present embodiment is composed of the proportional (P) and integral (I) compensators, but is composed of the proportional (P), integral (I) and differential (D) compensators. You may.

The coordinate inverse converter 505 reversely converts the drive voltages Vq and Vd in the rotating coordinate system output from the current controller 503 into the drive voltages Vα and Vβ in the stationary coordinate system by the following equation.

Vα = cosθ * Vd-sinθ * Vq (5)
Vβ = sinθ * Vd + cosθ * Vq (6)
The coordinate inverse converter 505 reversely converts the drive voltages Vq and Vd in the rotating coordinate system into the drive voltages Vα and Vβ in the stationary coordinate system, and then outputs Vα and Vβ to the thinning controller 519 and the PWM inverter 506. In the present embodiment, the drive voltages Vq and Vd corresponding to the current values iq * and id * are generated, and the drive voltages Vq and Vd are inversely transformed to obtain the drive voltages Vα and Vβ in the static coordinate system. I got it, but this is not the case. For example, the current values iq * and id * are inversely converted into the current values iα * and iβ * in the stationary coordinate system to generate the drive voltages Vα and Vβ corresponding to the current values iα * and iβ *. Is also good.

PWM inverter 506 have a full bridge circuit. Full bridge circuit is thus driven in a PWM signal based on the driving voltage Vα and Vβ inputted from the coordinate inverse transformer 505. As a result, the PWM inverter 506 generates drive currents iα and iβ corresponding to the drive voltages Vα and Vβ, and supplies the drive currents iα and iβ to the windings of each phase of the motor 509 to drive the motor 509. .. That, PWM inverter 506 functions as a supply means for supplying current to each phase winding of the motor 509. In the present embodiment, although the PWM inverter has a full-bridge circuit, a PWM inverter, for example, it may be configured with a half bridge circuit. The period to supply to the winding to generate a driving current iα and i.beta PWM inverter according to the driving voltage Vα and Vβ (hereinafter, referred to as an inverter cycle) electric current values obtainer 516 obtains the current value circumferential period to that out of sync. This is because the PWM inverter is driven by the drive voltages Vα and Vβ generated based on the current value acquired by the current value acquirer 516.

Next, a method of determining the rotation phase θ will be described.

As described above, the current values iα and iβ converted from analog values to digital values by the A / D converter 510, and the drive voltages Vα and Vβ output from the coordinate inverse converter 505 are also input to the thinning controller 519. Will be done. The current values iα and iβ and the drive voltages Vα and Vβ to which the thinning process applied by the thinning controller 519 is applied are output to the low-pass filter 514. The low-pass filter 514 reduces the signals of the harmonic components contained in the current values iα and iβ and the drive voltages Vα and Vβ, and induces the current values iα and iβ and the drive voltages Vα and Vβ in which the signals of the harmonic components are reduced. Output to the voltage determinant 512. That is, the low-pass filter 514 functions as a filter circuit in the present invention. The thinning controller 519 and the low-pass filter 514 will be described later.

The induced voltage determinant 512 determines the induced voltage generated in the winding of each phase of the motor by the rotation of the rotor. Specifically, the induced voltages Eα and Eβ are calculated by the following equations based on the current values iα and iβ output from the low-pass filter 514 and the drive voltages Vα and Vβ.

Eα = Vα-R * iα-L * diα / dt (7)
Eβ = Vβ-R * iβ-L * diβ / dt (8)
Here, R is the winding resistance and L is the winding inductance. The values of R and L are values specific to the motor 509 used, and are stored in advance in a memory (not shown) provided in the ROM 151b or the motor control device 157.

The induced voltages Eα and Eβ determined by the induced voltage determinant 512 are output to the phase determinant 513.

The phase determinant 513 determines the electric angle θ'of the drive current flowing in the winding of the motor 509 by the following equation based on the ratio of the induced voltage Eα and the induced voltage Eβ output from the induced voltage determinant 512.

θ'= tan ^ -1 (-Eβ / Eα) (9)
Further, the phase determinant 513 determines the rotation phase θ based on the electric angle θ ′ by the following equation.

θ = θ'* 2 / P (10)
Note that P is the number of magnetic poles of the rotor.

The rotation phase θ of the rotor 402 obtained as described above is input to the adder 101, the coordinate inverse converter 505, and the coordinate converter 511, and thereafter, the above-mentioned control is repeated.

As described above, in the vector control in the present embodiment, the motor is controlled by performing phase feedback control for controlling the current value in the rotating coordinate system so that the deviation between the command phase θ_ref and the rotation phase θ becomes small. .. When vector control is performed, it is possible to suppress the motor from being out of step, the increase in motor noise due to excess torque, and the increase in power consumption. Further, since the phase feedback control is performed, the rotation phase of the rotor can be controlled to be a desired phase. Therefore, in an image forming apparatus, a vector using phase feedback control for a motor that drives a load (for example, a registration roller) that needs to accurately control the rotation phase in order to properly form an image on a recording medium. Apply control. As a result, the image can be appropriately formed on the recording medium.

In the vector control in the present embodiment, the motor 509 is controlled by performing the above-mentioned phase feedback control, but the present invention is not limited to this. For example, the motor 509 may be controlled by feeding back the rotation speed ω of the rotor 402. Specifically, as shown in FIG. 5, a speed determinant 515 is provided inside the motor control device, and the speed determinant 515 determines the rotation speed ω based on the time change of the rotation phase θ output from the phase determinant 513. decide. The following equation (11) shall be used to determine the speed.

ω = dθ / dt (11)
Then, the CPU 151a outputs a command speed ω_ref indicating the target speed of the rotor. Further, a speed controller 500 is provided inside the motor control device, and the speed controller 500 generates the q-axis current command value iq_ref and the d-axis current command value id_ref so that the deviation between the rotation speed ω and the command speed ω_ref becomes small. And output. The motor 509 may be controlled by performing such speed feedback control. In such a configuration, since the rotation speed is fed back, the rotation speed of the rotor can be controlled to be a predetermined speed. Therefore, in the image forming apparatus, speed feedback control is applied to a motor that drives a load (for example, a photosensitive drum, a transport belt, etc.) in which the rotation speed needs to be controlled to a constant speed in order to properly form an image on a recording medium. Apply the vector control used. As a result, the image can be appropriately formed on the recording medium.

[Low-pass filter]
Next, the low-pass filter 514 according to the present embodiment will be described.

As described above, in the present embodiment, the rotation phase θ is determined based on the current value of the drive current detected by the current detectors 507 and 508. The detected current value includes a signal of a harmonic component of the fundamental frequency of the electric angle of the motor and the like. If the phase of the rotor is determined based on the current value including the signal of the harmonic component and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

Therefore, as shown in FIG. 3, the motor control device 157 in the present embodiment is provided with a low-pass filter 514 that reduces signals having a frequency higher than a predetermined frequency. The control of the motor becomes unstable by determining the phase of the rotor based on the current value at which the signal of the harmonic component is reduced by the low-pass filter and controlling the drive of the motor based on the phase determination result. Can be suppressed.

FIG. 6 is a block diagram showing an example of the configuration of the low-pass filter 514. The low-pass filter 514 in the present embodiment is a digital filter in which a predetermined filter order is set. The low-pass filter 514 will be described below. In the present embodiment, the filter order is set to the 30th order in advance. Further, in the present embodiment, the filter order can be changed within the range of 30th order or less.

As shown in FIG. 6, the low-pass filter 514 calculates a memory 514a that stores a plurality of current values output from the current value acquirer 516, and an average value of a plurality of current values stored in the memory 514a. An average value calculator 514b is provided.

The low-pass filter 514 acquires the current value output from the current value acquirer 516 and stores it in the memory 514a. Further, the average value calculator 514b calculates and outputs the average value of the current values stored in the memory 514a. Specifically, for example, when the order of the low-pass filter 514 is 30th, the low-pass filter 514 stores 30 current values output from the current value acquirer 516 in the memory 514a, and stores the 30 currents in the memory 514a. Calculate the average value of the values. When the memory 514a acquires the 31st and subsequent current values, the current acquired by deleting the oldest stored current value among the stored current values each time one current value is acquired. The value shall be stored. Further, the average value calculator 514b shall perform the above-mentioned calculation every time the memory 514a stores the current value. Further, the filter configuration is not limited to the configuration for calculating the average value as described above, and any digital filter capable of reducing the signal may be used.

When a low-pass filter composed of a digital filter is used to reduce a signal of a harmonic component, the frequency band in which the low-pass filter can be reduced differs depending on the order of the filter. Specifically, the higher the order of the filter, the more the signal of the low frequency harmonic component can be reduced. Therefore, in order to reduce the signal of the low frequency harmonic component, it is necessary to increase the order of the filter.

Further, the frequency of the harmonic component differs depending on the rotation speed of the rotor of the motor. Specifically, the slower the rotation speed of the rotor, the lower the frequency of the harmonic component. Therefore, the frequency of the harmonic component changes by changing the rotation speed of the rotor, and there is a possibility that the signal of the harmonic component cannot be reduced by the filter of the preset order. Specifically, for example, if the rotation speed of the rotor is slowed down, there is a possibility that the signal of the harmonic component cannot be reduced by the filter of the preset order. If the phase of the rotor is determined based on the current value in which the signal of the harmonic component is not reduced and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

Next, the frequency of the signal of the harmonic component will be described. In the following description, the motor A having 100 rotor magnetic poles (50 N poles and 50 S poles each) is used, but the number of magnetic poles of the motor used is not limited to this. Absent. Further, in the present embodiment, it is assumed that the cycle (sampling cycle) for the current value acquirer 516 to acquire the current value is 25 μs.

In the motor A, the mechanical angle (rotational phase θ) of 7.2 ° corresponds to the electric angle of 360 °. That is, when the rotor of the motor A makes one revolution, the electric angle makes 50 revolutions. Therefore, for example, when the motor A is driven at a rotation speed of 10 rps, the electric angular frequency is 500 Hz.

Not only the signals of these electric angular frequencies but also the signals of the harmonic components of the electric angular frequencies are superimposed on the drive current detected by the current detector. For example, the third-order component and the fifth-order component of the electric angular frequency are superimposed.

FIG. 7A is a diagram showing an example of signals of the primary component and the tertiary component of the electric angular frequency. Further, FIG. 7B is a diagram showing an example of a signal obtained by synthesizing the signal of the primary component and the signal of the tertiary component of the electric angular frequency. Further, FIG. 7 (c) is a diagram showing an example of an induced voltage determined based on the signal shown in FIG. 7 (b) and an electric angle determined based on the induced voltage.

As shown in FIG. 7C, when the electric angle θ'is determined based on the current value including the harmonic component of the electric angular frequency, the determined electric angle θ'becomes a distorted waveform. If the rotation phase θ is determined based on the distorted electric angle θ'of the waveform and the drive of the motor is controlled based on the rotation phase θ, the control of the motor becomes unstable. Therefore, for example, when the motor A is driven at a rotation speed of 10 rps, it is necessary to reduce the signal of 1500 Hz, which is a tertiary component of the electric angular frequency.

Next, the order of the filter required to reduce the signal of the harmonic component included in the detected drive current will be described. In the present embodiment, the order signal harmonic components are reduced, the average value of the data of the current value of all (included in the one period), which is the acquired one cycle of the harmonic component computation is necessary Ru Ru. Specifically, for example, if the period in which the period of the harmonic component current value acquiring unit to a 1000μs acquires a current value of 25 .mu.s, the number of electric current values acquired by one cycle of the harmonic component it is a four-zero. Therefore, in this case, the order period is reduced signal harmonic components is 1000 .mu.s, the order of the filter is required to be 4 0 or higher order. In the present embodiment, the average value of the data for all of the current value included in one period of the harmonic component signals of the harmonic component is configured that will be reduced by Rukoto computed, limited to It's not something. Eg, n cycles of the harmonic component (n is a positive integer) the average value of the data for all of the current value contained in may be configured that will be computed. Moreover, it is not a configuration all data of a current value contained in the n period that is used.

As described above, when the motor A is driven at a rotation speed of 10 rps, the frequency of the signal of the tertiary component of the electric angular frequency is 1500 Hz (period is 1/1500 S). Further, in the present embodiment, the period for the current value acquirer to acquire the current value is 25 μs. Therefore, when the motor A is driven at a rotation speed of 10 rps, the number of current values included in one cycle of the signal of the third-order component of the electric angular frequency can be obtained by using the following formula.

(1 / 1500s) / 25μs ≈ 26.7 (12)
Therefore, when the motor A is driven at a rotation speed of 10 rps, it is necessary to use a filter of the 27th order or higher in order to reduce the signal of the third-order component of the electric angular frequency.

Further, for example, when the motor A is driven at a rotation speed of 3 rps, the frequency of the signal of the third component of the electric angular frequency is 450 Hz (period is 1/450 S). Further, in the present embodiment, the period for the current value acquirer to acquire the current value is 25 μs. Therefore, when the motor A is driven at a rotation speed of 3 rps, the number of current values included in one cycle of the signal of the third-order component of the electric angular frequency can be obtained by using the following formula.

(1 / 450s) / 25μs ≈ 88.8 (13)
Therefore, when the motor A is driven at a rotation speed of 3 rps, it is necessary to use a filter of the 89th order or higher in order to reduce the signal of the third component of the electric angular frequency.

As described above, the frequency of the signal of the harmonic component differs depending on the rotation speed of the rotor. Therefore, when the rotation speed of the rotor is changed from 10 rps to 3 rps, the signal of the harmonic component cannot be reduced by the filter of the preset order. Specifically, when the motor A is driven at a rotation speed of 10 rps, the signal of the tertiary component can be reduced by setting the order of the filter to the 30th order. However, when the motor A is driven at a rotation speed of 3 rps, the signal of the tertiary component cannot be reduced if the order of the filter is 30th.

If the phase of the rotor is determined based on the current value in which the signal of the harmonic component is not reduced and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

In this case, it is conceivable to increase the order of the filter. That is, it is conceivable that the low-pass filter is configured so that the order of the filter can be set to 89 or higher. However, as the order of the filter is increased, the capacity of the memory 514a increases, and as a result, the cost increases. Further, the larger the order of the filter, the larger the amount of phase delay due to the filter processing. That is, since the amount of phase delay caused by the filter processing also changes by changing the order of the filter, there arises a problem that the configuration for correcting the phase delay becomes complicated. Therefore, even if the rotation speed is slowed down, there is a demand for a configuration that can reduce the signal of the harmonic component without increasing the order of the filter.

Hereinafter, as an example of the present embodiment, a method of reducing the signal of the harmonic component when the motor control device changes the rotation speed of the rotor from 10 rps to 3 rps in a state where the order of the filter is 30 rps will be described. To do.

As described in the equations (12) and (13), the order of the filter required to reduce the signal of the harmonic component is determined by the number of current value data included in one cycle of the harmonic component. .. That is, it is determined by the cycle (sampling cycle) in which the current value acquirer acquires the current value data. Specifically, the longer the sampling period, the smaller the number of current value data for one period of the harmonic component, so that the order of the filter can be made smaller.

Therefore, when the rotation speed at the time of driving the motor A is changed from 10 rps to 3 rps in a state where the order of the filter is 30th order, the signal of the harmonic component is reduced without increasing the order of the filter. The sampling cycle may be lengthened. However, as described above, since the sampling cycle and the inverter cycle are synchronized, the longer the sampling cycle, the longer the inverter cycle. If the inverter cycle becomes long, the responsiveness of the motor to the command output from the CPU 151a deteriorates. Further, if the inverter cycle is not 50 μs or less (frequency is 20 kHz or more), problems such as noise occur. That is, if the sampling period is not 50 μs or less (frequency is 20 kHz or more), problems such as noise occur. This is because the maximum value of the human audible frequency region is about 20 kHz. Even if the sampling period is set to 50 μs, it is necessary to set the order of the filter to 45 or higher in order to reduce the signal of the third-order component at a rotation speed of 3 rps. That is, even if the sampling period is set to 50 μs, the signal of the third-order component at a rotation speed of 3 rps cannot be reduced while the order of the filter is 30.

[Thinning control]
As shown in FIG. 3, the motor control device 157 in this embodiment is provided with a thinning controller 519. The current value acquirer 516 outputs the current values iα and iβ acquired from the A / D converter 510 to the thinning controller 519. Further, the coordinate inverse converter 505 outputs the voltage values Vα and Vβ of the drive voltage to the thinning controller 519. The thinning controller 519 thins out some data of all the acquired current values and voltage values and outputs the data to the low-pass filter 514.

FIG. 8 is a diagram illustrating a method of thinning out a part of data among all the current values and voltage values acquired by the thinning controller 519. The method of thinning out a part of the data of all the current values acquired by the thinning controller 519 will be described below. The method of thinning out a part of the voltage value data is the same as the method of thinning out a part of the current value data, and thus the description thereof will be omitted.

As shown in FIG. 8, the thinning controller 519 thins out a part of the data of all the current values acquired by the current value acquirer 516 in the sampling period of 25 μs based on the determined thinning rate. That is, the thinning controller 519 performs the thinning process so that the time interval of the current value data after the thinning process is, for example, 100 μs. Further, the thinning controller 519 outputs the data of the current value after the thinning process to the low-pass filter 514. The thinning rate is 0 when the data is not thinned out, and the larger the thinning rate, the larger the number of data to be thinned out. As a result, the current value data is apparently acquired by the current value acquirer 516 with a sampling period of 100 μs and input to the low-pass filter 514. In this case, in the case of driving the motor A at a rotational speed 3Rps, the number of electric current values acquired by one period of the signal of the third-order component of the electrical angle frequency is determined using the following equation.

(1 / 450s) / 100μs ≈ 22.2 (14)
Therefore, in this case, if a filter of the 23rd order or higher is used, the signal of the 3rd order component of the electric angular frequency when the motor A is driven at the rotation speed of 3 rps can be reduced. That is, the signal of the third-order component at a rotation speed of 3 rps can be reduced while the order of the filter is 30th. In this case, the order of the filter may be changed to the 23rd order.

Next, a method of determining (setting) the thinning rate in the present embodiment will be described. In the present embodiment, the thinning rate is determined based on the rotation speed of the rotor. In the following description, it is assumed that the sampling period is 25 μs and the filter order of the low-pass filter is 30th order.

The CPU 151a in the present embodiment calculates a rotation speed ω_ref ′ instead of the command speed ω_ref based on the time change of the command phase θ_ref. The equation (11) is used for the calculation. The CPU 151a determines the thinning rate by the method described above based on the rotation speed ω_ref', the sampling period, and the filter order of the low-pass filter. Specifically, the thinning rate is determined as in Eq. (14) so that the signal of the harmonic component can be reduced even if the filter order is 30th. The CPU 151a outputs the determined thinning rate to the thinning controller 519.

If the thinning rate is too large, the number of current value data is too small, and there is a possibility that the phase cannot be determined accurately. In the present embodiment, it is assumed that the phase can be accurately determined if there is data of 32 current values per cycle in the signal of the primary component of the electric angular frequency of the motor, but the present invention is limited to this. is not. Therefore, when the thinning rate is determined, the thinning rate is determined so that there are at least 32 current value data per cycle in the signal of the primary component of the electric angular frequency of the motor.

Further, in the present embodiment, the CPU 151a is determined by calculating the thinning rate based on the rotation speed ω_ref', the sampling period, and the filter order of the low-pass filter, but this is not the case. For example, a table showing the relationship between the rotation speed ω_ref'and the thinning rate may be provided inside the CPU 151a, and the thinning rate may be determined based on the table.

Further, in the present embodiment, the CPU 151a determines the thinning rate, but this is not the case. For example, the rotation speed ω_ref'may be input to the thinning controller 519, and the thinning controller 519 may determine the thinning rate by the method described above.

The thinning controller 519 performs thinning processing on the current values iα and iβ and the voltage values Vα and Vβ based on the input thinning rate, and applies the thinning processing to the current values iα and iβ and the voltage values Vα and Vβ. Output to the low-pass filter 514. The low-pass filter 514 reduces the signal of the harmonic component by the method described above. Further, the phase determinant 513 determines the phase θ based on the reduced current value of the harmonic component signal, and the motor control device 157 controls the drive of the motor based on the phase determination result. As a result, it is possible to prevent the control of the motor from becoming unstable.

FIG. 9 is a flowchart showing a method in which the motor control device in the present embodiment determines the thinning rate. Hereinafter, a method for determining the thinning rate in the present embodiment will be described with reference to FIG. 9. The processing of this flowchart is executed by the motor control device 157 that receives the instruction from the CPU 151a. In the following description, it is assumed that the filter order is set to the 30th order in advance. The sampling period is 25 μs.

First, in S101, when the enable signal ‘H’ is output from the CPU 151a to the motor control device 157, the motor control device 157 starts the drive control of the motor 509 based on the command output from the CPU 151a. The enable signal is a signal for permitting or prohibiting the operation of the motor control device 157. When the enable signal is'L (low level)', the CPU 151a prohibits the operation of the motor control device 157. That is, the control of the motor 509 by the motor control device 157 is terminated. When the enable signal is'H (high level)', the CPU 151a permits the operation of the motor control device 157, and the motor control device 157 controls the drive of the motor 509 based on the command output from the CPU 151a. Do.

Next, in S102, when the rotation speed ω_ref'is 10 rps or more, the CPU 151a sets the thinning rate to 0 in S103. This is because if the rotation speed ω_ref'is 10 rps or more, even if the filter order is 30th order, the signal of the harmonic component can be reduced without thinning out the current value data. The CPU 151a outputs the determined thinning rate to the thinning controller 519. After that, the motor control device 157 advances the process to S105.

Further, in S102, when the rotation speed ω_ref'is smaller than 10 rps, the CPU 151a sets the thinning rate to a value larger than 0 in S104. The thinning rate is set so that the following two conditions are satisfied. The first condition is that there are 32 or more current value data after thinning in the signal of the primary component of the electric angular frequency of the motor per cycle. The second condition is that the thinning rate is set based on the rotation speed ω_ref'. Specifically, for example, when the rotation speed ω_ref'is 5 rps, the thinning rate corresponding to 5 rps is set, and when the rotation speed ω_ref'is 3 rps, the thinning rate corresponding to 3 rps is set. The CPU 151a outputs the determined thinning rate to the thinning controller 519. After that, the motor control device 157 advances the process to S105.

Next, in S105, the motor control device 157 thins out the current value data acquired by the current value acquirer 516 based on the determined thinning rate, and filters the thinned out current value data. To give. Then, the motor control device 157 performs the above-mentioned vector control based on the filtered current value data .

After that, the motor control device 157 repeats the above-mentioned control until the CPU 151a outputs the enable signal ‘L’ to the motor control device 157 to control the motor 509. In the present embodiment, the thinning rate is set to 0 at 10 rps, which is the rotation speed of the rotor capable of removing the signal of the harmonic component without performing the thinning control with the preset filter order (30th order). Although it is set as a threshold value for or not, it is not limited to this.

As described above, in the present embodiment, the thinning process of the current value and the voltage value data is performed, and the current value and the voltage value to which the thinning process is applied are filtered. As a result, the signal of the harmonic component can be reduced without lengthening the sampling period or increasing the filter order. In addition, the thinning rate is determined according to the rotation speed of the rotor. Specifically, when the rotation speed ω_ref'is 10 rps or more, the thinning rate is determined to be 0. That is, the thinning controller 519 does not perform the thinning process. When the rotation speed ω_ref'is smaller than 10 rps, the thinning rate is set to a value larger than 0. As a result, even if the frequency of the harmonic component changes due to the change in the rotation speed of the rotor, the signal of the harmonic component can be displayed without increasing the order of the filter to a preset order. It can be reduced.

In this embodiment, the motor control device controls the motor based on the mechanical angle. That is, the CPU 151a outputs the command phase of the machine angle to the motor control device, and the phase determinant 513 determines the rotation phase (machine angle) of the rotor. Then, the adder calculates the deviation between the command phase and the rotation phase, and the phase controller outputs the command current value based on the deviation, but this is not the case. For example, the motor control device may be configured to control the motor based on the electric angle. Specifically, for example, the CPU 151a outputs a command phase, which is a target phase of the electric angle of the drive current, to the motor control device, and the phase determinant 513 determines the phase of the electric angle of the drive current. Further, the adder may calculate the deviation between the command phase of the electric angle and the phase of the determined electric angle, and the phase controller may output the command current value based on the deviation. ..

Further, in the vector control in the present embodiment, a rotating coordinate system based on the rotation phase θ of the rotor 402 is used, but the present invention is not limited to this. For example, a rotating coordinate system based on the command phase θ_ref may be used.

The thinning process in the present embodiment may be applied not only to the filter process by the low-pass filter but also when a band-pass filter or the like is used.

Further, in the present embodiment, the thinning rate is determined based on the rotation speed ω_ref ′ instead of the command speed ω_ref, but the thinning rate is not limited to this. For example, the thinning rate may be determined based on the rotation speed ω determined by the speed determinant 515 shown in FIG.

Further, in the present embodiment, when the rotation speed ω_ref'is 10 rps or more, the thinning rate is set to 0, but the thinning rate is not limited to this, and the thinning control is performed even when the rotation speed ω_ref'is 10 rps or more. Is also good. In this case, the thinning rate when the rotation speed ω_ref'is smaller than 10 rps is determined to be larger than the thinning rate when the rotation speed ω_ref' is 10 rps or more.

[Second Embodiment]
The configuration of the image forming apparatus and the low-pass filter 514 is the same as that of the first embodiment. Hereinafter, a method in which the motor control device in the present embodiment controls the motor will be described. Since the motor drive control method using vector control and the configuration of the low-pass filter 514 are the same as those in the first embodiment, the description thereof will be omitted.

As described above, when a low-pass filter composed of a digital filter is used to reduce a signal of a harmonic component, the frequency band in which the low-pass filter can be reduced differs depending on the order of the filter. Specifically, the higher the order of the filter, the more the signal of the low frequency harmonic component can be reduced. Therefore, in order to reduce the signal of the low frequency harmonic component, it is necessary to increase the order of the filter.

The frequency of the harmonic component also differs depending on the type of motor. Therefore, when different types of motors are installed by replacing the motors, it may not be possible to reduce the harmonic component signal with a preset order filter. Specifically, for example, when the frequency of the harmonic component included in the detection current of the motor after replacement is lower than the frequency of the harmonic component contained in the detection current of the motor before replacement, it is preset. It may not be possible to reduce noise with a filter of the same order. If the phase of the rotor is determined based on the current value in which the signal of the harmonic component is not reduced and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

Next, the frequency of the signal of the harmonic component will be described. In the following description, the motor A in which the number of magnetic poles of the rotor is 100 (50 for each of the north and south poles) and the number of magnetic poles for the rotor are 24 (the north and south poles are each). A motor B, which is 12 each), is used. However, the number of magnetic poles of the motor used is not limited to this. Further, in the present embodiment, it is assumed that the cycle (sampling cycle) for the current value acquirer 516 to acquire the current value is 25 μs.

As described in the first embodiment, when the motor A is driven at a rotation speed of 10 rps, the electric angular frequency is 500 Hz.

Further, in the motor B having 24 magnetic poles, the mechanical angle of 30 ° corresponds to the electric angle of 360 °. That is, when the rotor of the motor B makes one revolution, the electric angle makes 12 revolutions. Therefore, for example, when the motor B is driven at a rotation speed of 10 rps, the electric angular frequency is 120 Hz.

Not only the signals of these electric angular frequencies but also the signals of the harmonic components of the electric angular frequencies are superimposed on the drive current detected by the current detector. For example, the third-order component and the fifth-order component of the electric angular frequency are superimposed.

Therefore, when the motor A is driven at a rotation speed of 10 rps, it is necessary to reduce the signal of 1500 Hz, which is a tertiary component of the electric angular frequency. Further, when the motor B is driven at a rotation speed of 10 rps, it is necessary to reduce the signal of 360 Hz, which is a tertiary component of the electric angular frequency.

Next, the order of the filter required to reduce the signal of the harmonic component included in the detected drive current will be described. In order to reduce the signal of the harmonic component, it is necessary to calculate the average value of the data of all the current values included in one cycle of the harmonic component. Specifically, for example, when the period of the harmonic component is 1000 μs and the period of acquiring the current value by the current value acquirer is 25 μS, the number of current values included in one period of the harmonic component is 4. There are 0 pieces. Therefore, in this case, since the period to reduce the signal of the harmonic component is 1000μs the order of the filter is required to be 4 0 or higher order. In the present embodiment, the signal of the harmonic component is reduced by calculating the average value of the data of all the current values included in one cycle of the harmonic component, but the present invention is limited to this. is not. For example, the configuration may be such that the average value of the data of all the current values included in the n period (n is a positive integer) of the harmonic component is calculated. Further, it is not necessary to use all the current value data included in n cycles.

As described in the first embodiment, when the motor A is driven at a rotation speed of 10 rps, it is necessary to use a filter of the 27th order or higher in order to reduce the signal of the third component of the electric angular frequency.

Further, when the motor B is driven at a rotation speed of 10 rps, the frequency of the signal of the third component of the electric angular frequency is 360 Hz (period is 1/360 S). Therefore, when the motor B is driven at a rotation speed of 10 rps, the number of current values included in one cycle of the signal of the third-order component of the electric angular frequency can be obtained by using the following formula.

(1 / 360s) / 25μs ≒ 111.1 (15)
Therefore, when the motor B is driven at a rotation speed of 10 rps, it is necessary to use a filter of degree 112 or higher in order to reduce the signal of the third-order component of the electric angular frequency.

As described above, the frequency of the signal of the harmonic component differs depending on the number of magnetic poles of the motor. Therefore, when motors having different numbers of magnetic poles are attached by replacing the motors, it may not be possible to reduce the signal of the harmonic component by the filter of the preset order. Specifically, for example, when the motor before the replacement is the motor A and the motor after the replacement is the motor B, the signal of the harmonic component is reduced by the filter of the preset order. It may not be possible. More specifically, for example, when controlling the drive of the motor A, the signal of the tertiary component can be reduced by setting the order of the filter to the 30th order. However, when the motor A is replaced with the motor B, the signal of the tertiary component cannot be reduced when the order of the filter is 30th.

If the phase of the rotor is determined based on the current value in which the signal of the harmonic component is not reduced and the drive of the motor is controlled based on the phase determination result, the control of the motor becomes unstable.

In this case, it is conceivable to increase the order of the filter. That is, it is conceivable that the configuration of the low-pass filter is such that the order of the filter can be set to 112th or higher. However, as the order of the filter is increased, the capacity of the memory 514a increases, and as a result, the cost increases. Further, the larger the order of the filter, the larger the amount of phase delay due to the filter processing. That is, since the amount of phase delay caused by the filter processing also changes by changing the order of the filter, there arises a problem that the configuration for correcting the phase delay becomes complicated. Therefore, even when different types of motors are installed by replacing the motors, there is a need for a configuration that can reduce the signals of low-frequency harmonic components without increasing the order of the filter. There is.

Hereinafter, as an example of the present embodiment, a method for reducing a signal of a harmonic component when a motor controlled by a motor control device is replaced from a motor A to a motor B in a state where the order of the filter is 30th order will be described. explain.

As described in the equations (12) to (15), the order of the filter required to reduce the signal of the harmonic component is determined by the number of current values included in one cycle of the harmonic component. That is, it is determined by the cycle (sampling cycle) in which the current value acquirer acquires the current value data. Specifically, the longer the sampling period, the smaller the number of current value data for one period of the harmonic component, so that the order of the filter can be made smaller.

Therefore, when the motor is replaced from the motor A to the motor B in a state where the order of the filter is 30th order, in order to reduce the signal of the low frequency harmonic component without increasing the order of the filter, it is necessary to reduce the signal. The sampling cycle may be lengthened. However, as described above, since the sampling cycle and the inverter cycle are synchronized, the longer the sampling cycle, the longer the inverter cycle. If the inverter cycle becomes long, the responsiveness of the motor control device to the command output from the CPU 151a deteriorates. Further, if the inverter cycle is not 50 μs or less (frequency is 20 kHz or more), problems such as noise occur. That is, if the sampling period is not 50 μs or less (frequency is 20 kHz or more), problems such as noise occur. This is because the maximum value of the human audible frequency region is about 20 kHz. Even if the sampling period is set to 50 μs, it is necessary to set the order of the filter to 56th order or higher in order to reduce the signal of the third-order component in the motor B. That is, even if the sampling period is set to 50 μs, the signal of the third-order component in the motor B cannot be reduced while the order of the filter is 30th.

[Thinning control]
FIG. 10 is a block diagram showing the configuration of the motor control device 157 according to the present embodiment.

As shown in FIG. 10, the motor control device 157 in this embodiment is provided with a thinning controller 519. The current value acquirer 516 outputs the current values iα and iβ acquired from the A / D converter 510 to the thinning controller 519. Further, the coordinate inverse converter 505 outputs the voltage values Vα and Vβ of the drive voltage to the thinning controller 519. The thinning controller 519 thins out some data of all the acquired current values and voltage values and outputs the data to the low-pass filter 514.

The thinning controller 519 thins out a part of the data of all the current values acquired by the current value acquirer 516 in the sampling period of 25 μs based on the determined thinning rate. That is, the thinning controller 519 performs the thinning process so that the time interval of the current value data after the thinning process is, for example, 100 μs. Further, the thinning controller 519 outputs the data of the current value after the thinning process to the low-pass filter 514. As a result, the current value data is apparently acquired by the current value acquirer 516 with a sampling period of 100 μs and input to the low-pass filter 514. In this case, when the motor B is driven at a rotation speed of 10 rps, the number of current values included in one cycle of the signal of the third-order component of the electric angular frequency is obtained by using the following formula.

(1 / 360s) / 100μs ≈ 27.7 (15)
Therefore, in this case, if a filter of 28th order or higher is used, it is possible to reduce the signal of the tertiary component of the electric angular frequency when the motor B is driven at a rotation speed of 10 rps. That is, the signal of the third-order component in the motor B can be reduced while the order of the filter is 30th. In this case, the order of the filter may be changed to the 28th order.

Next, a method of determining the type of motor attached to the motor control device and a method of determining the thinning rate based on the determination result will be described. In the present embodiment, the number of magnetic poles of the attached motor is determined, and the thinning rate is determined based on the determination result. In the following description, it is assumed that the motor is driven at a rotation speed of 10 rps. Further, it is assumed that the sampling period is 25 μs and the filter order of the low-pass filter is 30th order.

In the present embodiment, the information acquirer 700 shown in FIG. 10 acquires motor information. Specifically, the motor attached to the motor control device 157 is provided with, for example, a bar code for determining the type of the motor, and the information acquirer 700 reads the bar code. The information acquirer 700 is provided with a table 701 showing the relationship between the barcode and the motor information, and the information acquirer 700 acquires the motor information by referring to the table 701. The motor information corresponds to, for example, the number of magnetic poles of the rotor of the motor. The information acquirer 700 outputs the acquired information to the CPU 151a.

In the present embodiment, the information acquirer 700 acquires the information of the motor by reading the bar code attached to the motor, but the present invention is not limited to this. For example, when the serviceman replaces the motor, the operation unit 152 may be used to transmit information on the attached motor to the CPU 151a.

The CPU 151a determines the thinning rate by the method described above based on the number of magnetic poles of the motor, the rotation speed of the motor, the sampling period, and the filter order of the low-pass filter. Specifically, the thinning rate is determined as in Eq. (15) so that the signal of the harmonic component can be reduced even if the filter order is 30th. The CPU 151a outputs the determined thinning rate to the thinning controller 519. The thinning controller 519 stores the input thinning rate in a memory (not shown).

If the thinning rate is too large, the number of current value data is too small, and there is a possibility that the phase cannot be determined accurately. In the present embodiment, if there is data of 32 current values per cycle in the signal of the primary component of the electric angular frequency of the motor, the phase can be determined accurately. Therefore, when the thinning rate is determined, the thinning rate is determined so that there are at least 32 current value data per cycle in the signal of the primary component of the electric angular frequency of the motor.

Further, in the present embodiment, the CPU 151a is determined by calculating the thinning rate based on the motor information, the rotation speed, the sampling period, and the filter order of the low-pass filter, but this is not the case. For example, a table showing the relationship between the motor information and the thinning rate may be provided inside the CPU 151a, and the thinning rate may be determined based on the table.

Further, in the present embodiment, the CPU 151a determines the thinning rate, but this is not the case. For example, the information of the motor, the rotation speed, and the like may be input to the thinning controller 519, and the thinning controller 519 may determine the thinning rate.

The thinning controller 519 performs thinning processing on the current values iα and iβ and the voltage values Vα and Vβ based on the thinning rate stored in the memory, and applies the thinning processing to the current values iα and iβ and the voltage value Vα. And Vβ are output to the low pass filter 514. The low-pass filter 514 reduces the signal of the harmonic component by the method described above. Further, the phase determinant 513 determines the phase θ based on the reduced current value of the harmonic component signal, and the motor control device 157 controls the drive of the motor based on the phase determination result. As a result, it is possible to prevent the control of the motor from becoming unstable.

FIG. 11A is a diagram showing a waveform of a current acquired by the current value acquirer 516 in a sampling period of 25 μs when the motor B is driven at a rotation speed of 10 rps. As shown in FIG. 11A, the current waveform is distorted due to harmonic components such as the third-order component of the electric angular frequency.

FIG. 11B is a diagram showing a waveform of the current when a thirty-order filter is applied to the current shown in FIG. 11A. When the motor B is driven at a rotation speed of 10 rps, the frequency of the signal that can be reduced by the 30th-order filter is derived by the following equation (16).

1 / (25 μs * 30) = 1333.3 (16)
Therefore, when the motor B is driven at a rotation speed of 10 rps, the signal of the harmonic component having a frequency of 1333.3 Hz or more can be reduced by using a 30th-order filter. Since the primary component of the electric angular frequency when the motor B is driven at a rotation speed of 10 rps is 120 Hz, the current waveform shown in FIG. 11B is the 12th order of the electric angular frequency by applying the 30th order filter. The signals of the above components are reduced. However, as described above, even if the 30th-order filter is applied to the current value data acquired by the current value acquirer 516 in the sampling period of 25 μs while the motor B is being driven at a rotation speed of 10 rps, the electric angular frequency It is not possible to reduce the signal of the tertiary component of. Therefore, in the current waveform shown in FIG. 11B, distortion due to harmonic components such as the third-order component of the electric angular frequency remains.

FIG. 11C is a diagram showing a waveform of the current when the thinning process is applied to the current shown in FIG. 11B. Compared to the current waveform shown in FIG. 11 (b), the current waveform shown in FIG. 11 (c) has a reduced signal of a component of the third order or higher of the electric angular frequency by applying the thinning process described above. By determining the phase θ based on the current waveform shown in FIG. 11 (c) and controlling the drive of the motor based on the phase determination result, it is possible to suppress the control of the motor from becoming unstable.

FIG. 12 is a flowchart showing a method in which the motor control device in the present embodiment determines the thinning rate. Hereinafter, a method for determining the thinning rate in the present embodiment will be described with reference to FIG. The processing of this flowchart is executed by the CPU 151a. The processing of this flowchart is executed, for example, by inputting to the CPU 151a using the operation unit 152 that the motor has been replaced when the serviceman has replaced the motor. In the following description, it is assumed that the filter order is set to the 30th order in advance. The rotation speed of the rotor is 10 rps. Further, the sampling period is 25 μs.

First, when the motor is replaced in S201, in S202, the information acquirer 700 acquires the information (information on the number of magnetic poles) of the attached motor by the method described above. Next, in S203, the rotor of the attached motor. When the number of magnetic poles is 100 or more, the CPU 151a advances the process to S204. In S204, the CPU 151a determines the thinning rate to 0. This is because if the number of magnetic poles is 100 or more, the signal of the harmonic component can be reduced without thinning out the current value data even if the filter order is 30th. The CPU 151a outputs the determined thinning rate to the thinning controller 519. After that, the CPU 151a advances the process to S206.

Further, in S203, when the number of magnetic poles of the rotor of the attached motor is less than 100, the CPU 151a advances the process to S205. In S205, the CPU 151a sets the thinning rate to a value larger than 0 by the method described above. The thinning rate is set so that the following two conditions are satisfied. The first condition is that there are 32 or more current value data after thinning in the signal of the primary component of the electric angular frequency of the motor per cycle. The second condition is that the thinning rate is set based on the number of magnetic poles. Specifically, for example, when the number of magnetic poles is 50, the thinning rate corresponding to 50 magnets is set, and when the number of magnetic poles is 24, the thinning rate corresponding to 24 magnets is set. The CPU 151a outputs the determined thinning rate to the thinning controller 519. After that, the CPU 151a advances the process to S206.

After that, in S206, the thinning controller 519 stores the input thinning rate in a memory (not shown).

As described above, in the present embodiment, the current value and the voltage value data are thinned out, and the current value and the voltage value to which the thinning out process is applied are filtered. As a result, the signal of the harmonic component can be reduced without lengthening the sampling period or increasing the filter order. Further, when the motor is replaced, the thinning rate for thinning out the current value and voltage value data is determined according to the type (number of magnetic poles) of the attached motor. Specifically, when the user inputs to the CPU 151a using the operation unit 152 that the motor has been replaced, the CPU 151a determines the thinning rate based on the number of magnetic poles of the motor. More specifically, when the number of magnetic poles of the rotor is 100 or more, the thinning rate is determined to be 0. That is, the thinning controller 519 does not perform the thinning process. When the number of magnetic poles of the rotor is less than 100, the thinning rate is set to a value larger than 0. As a result, even if the frequency of the harmonic component contained in the detected current of the motor after replacement is lower than the frequency of the harmonic component contained in the detected current of the motor before replacement, the order of the filter is increased. The signal of the harmonic component can be reduced without increasing the value. That is, even when a different type of motor is attached by replacing the motor, the signal of the harmonic component can be reduced without increasing the order of the filter to a preset order. ..

Further, in the present embodiment, the motor control device controls the motor based on the mechanical angle. That is, the CPU 151a outputs the command phase of the machine angle to the motor control device, and the phase determinant 513 determines the rotation phase (machine angle) of the rotor. Then, the adder calculates the deviation between the command phase and the rotation phase, and the phase controller outputs the command current value based on the deviation, but this is not the case. For example, the motor control device may be configured to control the motor based on the electric angle. Specifically, for example, the CPU 151a outputs a command phase, which is a target phase of the electric angle of the drive current, to the motor control device, and the phase determinant 513 determines the phase of the electric angle of the drive current. Further, the adder may calculate the deviation between the command phase of the electric angle and the phase of the determined electric angle, and the phase controller may output the command current value based on the deviation. ..

Further, in the vector control in the present embodiment, a rotating coordinate system based on the rotation phase θ of the rotor 402 is used, but the present invention is not limited to this. For example, a rotating coordinate system based on the command phase θ_ref may be used.

The thinning process in the present embodiment may be applied not only to the filter process by the low-pass filter but also when a band-pass filter or the like is used.

Further, in the present embodiment, when determining the thinning rate, the rotation speed ω_ref'instead of the command speed ω_ref is used, but the present invention is not limited to this. For example, the thinning rate may be determined using the rotation speed ω determined by the speed determinant 515 shown in FIG.

Further, in the present embodiment, the thinning rate is set to 0 when the number of magnetic poles is 100 or more, but the thinning rate is not limited to this, and the thinning control may be performed even when the number of magnetic poles is 100 or more. .. In this case, the thinning rate when the number of magnetic poles is less than 100 is determined to be larger than the thinning rate when the number of magnetic poles is 100 or more.

In this embodiment, the number of magnetic poles of the rotor is set to 100 as a threshold value for whether or not the thinning rate is set to 0, but the present invention is not limited to this.

In the present embodiment, the rotation speed when driving the motor is set to 10 rps, and the method for determining the thinning rate when the motor A and the motor B are replaced has been described, but the present invention is not limited to this. For example, a combination of a configuration for determining the thinning rate based on the rotation speed as described in the first embodiment and a configuration for determining the thinning rate based on the number of magnetic poles of the motor as described in the present embodiment are combined. You may. That is, the thinning rate may be determined based on the rotation speed of the rotor and the number of magnetic poles of the motor. As a result, even when the motor is replaced and the motor is driven at a plurality of rotation speeds, the signal of the harmonic component can be reduced without increasing the order of the filter.

[Third Embodiment]
The configuration of the image forming apparatus and the low-pass filter 514 is the same as that of the first embodiment. Hereinafter, a method in which the motor control device in the present embodiment controls the motor will be described. Since the motor drive control method using vector control and the configuration of the low-pass filter 514 are the same as those in the first embodiment, the description thereof will be omitted.

In the first embodiment and the second embodiment, as shown in FIGS. 3 and 10, the current value acquired by the current value acquirer 516 is used to control the drive current supplied to the winding and to determine the rotation phase. Used to determine. In the process of determining the rotation phase, it is necessary to lengthen the sampling period in order to reduce the signal of the third-order component of the harmonic component with a preset filter order. However, since the sampling cycle and the inverter cycle are synchronized, the longer the sampling cycle, the longer the inverter cycle. As a result, in the process of controlling the drive current supplied to the winding, the responsiveness of the motor deteriorates and problems such as noise occur. Therefore, in the first embodiment and the second embodiment, all the current values acquired in the sampling period of 25 μs, in which the above-mentioned problems are unlikely to occur, are used for controlling the drive current to be supplied to the winding. Further, in the process of determining the rotation phase, a part of all the current values acquired in the sampling period of 25 μs was used. Specifically, a part of the data of all the current values acquired in the sampling period of 25 μs was thinned out based on the determined thinning rate so that the sampling period was apparently lengthened.

In the present embodiment, as shown in FIG. 13, when the motor control device 157 determines the rotation phase with the current value acquirer 516 that acquires the current value used when controlling the drive current supplied to the winding. A current value / voltage value acquirer 520 for acquiring the current value and the voltage value used in the above is provided. That is, a configuration for acquiring data used for controlling the drive current supplied to the winding and a configuration for acquiring data used for determining the rotation phase are provided separately.

The current value / voltage value acquirer 520 has a configuration in which the sampling cycle can be changed. Regarding the method of determining the sampling period of the current value / voltage value acquirer 520, the method of determining based on the rotation speed ω_ref'as described in the first embodiment or the magnetic pole as described in the second embodiment. It shall be possible to apply a method of determination based on numbers.

In the above configuration, if the sampling period of the current value acquirer 516 is set to 25 μs, the responsiveness of the motor deteriorates even if the sampling period of the current value / voltage value acquirer 520 is set to 50 μs or more. It is possible to reduce the occurrence of problems such as noise and noise. That is, the signal of the harmonic component is transmitted without causing problems such as deterioration of the responsiveness of the motor and noise, without making the filter order larger than the preset order, and without performing the thinning process. It can be reduced.

157 Motor controller 402 Rotor 502 Phase controller 503 Current controller 507, 508 Current detector 509 Stepping motor 510 A / D converter 513 Phase determiner 514 Low-pass filter 516 Current value acquirer

Claims (15)

In a motor control device that controls a drive current flowing through a winding of the motor based on a command phase representing a target phase of the rotor of the motor.
An acquisition means for acquiring the current value of the drive current flowing through the winding at a predetermined cycle, and
A filter circuit that reduces the harmonic component of the fundamental frequency of the drive current included in the signal represented by the current value acquired by the acquisition means, and
A phase determining means for determining the rotational phase of the rotor based on the signal after the filter processing by the filter circuit is applied, and
A control means for controlling the drive current flowing through the winding so that the deviation between the command phase and the rotation phase determined by the phase determining means becomes small.
Have,
The motor control is characterized in that the filter circuit reduces the harmonic component based on a number of current values less than the number of current values that can be acquired by the acquisition means within a period of one cycle of the harmonic component. apparatus. In a motor control device that controls a drive current flowing through a winding of the motor based on a command speed representing a target speed of the rotor of the motor.
An acquisition means for acquiring the current value of the drive current flowing through the winding at a predetermined cycle, and
A filter circuit that reduces the harmonic component of the fundamental frequency of the drive current included in the signal represented by the current value acquired by the acquisition means, and
A speed determining means for determining the rotation speed of the rotor based on the signal after the filter processing by the filter circuit is applied, and
A control means for controlling the drive current flowing through the winding so that the deviation between the command speed and the rotation speed determined by the speed determination means becomes small.
Have,
The motor control is characterized in that the filter circuit reduces the harmonic component based on a number of current values less than the number of current values that can be acquired by the acquisition means within a period of one cycle of the harmonic component. apparatus. The motor control device has a thinning means for thinning a part of all current value data acquired by the acquiring means within the period at a predetermined thinning rate.
When the motor is driven at the first speed, the thinning means thins out the current value data at the first thinning rate, and the motor is driven at a second speed slower than the first speed. If so, the current value data is thinned out at a second thinning rate that is higher than the first thinning rate.
The motor control device according to claim 1 or 2, wherein the filter circuit reduces the harmonic component based on a current value after the thinning process by the thinning means is applied. The motor control device according to claim 3, wherein the thinning means does not thin out the data of the current value when the motor is driven at a predetermined rotation speed or higher. The motor control device has a thinning means for thinning a part of data of all current values acquired by the acquiring means in the predetermined cycle at a predetermined thinning rate.
The thinning means does not thin out the data of the current value when the number of magnetic poles of the motor controlled by the control means is equal to or more than a predetermined number, and when the number of magnetic poles is less than the predetermined number, the magnetic poles The motor control device according to claim 1 or 2, wherein the data of the current value is thinned out at a thinning rate determined based on the number. The motor control device has a thinning means for thinning a part of data of all current values acquired by the acquiring means in the predetermined cycle at a predetermined thinning rate.
The thinning means is characterized in that the data of the current value is thinned out at a thinning rate determined based on the number of magnetic poles of the motor controlled by the control means and the rotation speed at which the motor is driven. 2. The motor control device according to 2. The filter circuit
It has a storage means for storing a predetermined number of current values after the thinning process by the thinning means is applied.
Further, claim 3 to the present invention, wherein the filter circuit is a digital filter that reduces the harmonic component by calculating the average value of the predetermined number of current values stored in the storage means. The motor control device according to any one of 6. The motor control device according to any one of claims 1 to 7, wherein the frequency of the harmonic component is determined based on the number of magnetic poles of the motor controlled by the control means. The motor control device according to any one of claims 1 to 8, wherein the harmonic component is a third-order component of the fundamental frequency. The motor control device according to any one of claims 1 to 9, wherein the harmonic component is a fifth-order component of the fundamental frequency. The control means is based on a torque current component which is a current component of a current value represented in a rotating coordinate system based on the rotation phase of the rotor and which is a current component for generating torque in the rotor. The motor control device according to any one of claims 1 to 10, wherein the drive current is controlled. The control means
It has a supply means for generating and outputting a drive current to be supplied to each of the first phase winding and the second phase winding of the motor.
The invention according to any one of claims 1 to 11, wherein the predetermined cycle in which the acquisition means acquires a current value is synchronized with a cycle in which the supply means generates and outputs the drive current. Motor control device. A transport roller that transports the sheet and
The motor that drives the transfer roller and
A motor control apparatus according to any one of claims 1 to 1 2,
Have,
The motor control device is a sheet transfer device that controls the drive of a motor that drives the transfer roller. The document loading section for loading documents and
A feeding unit that feeds the documents loaded on the document loading unit,
Reading means for reading the feeding has been originals by pre Symbol feed unit,
The motor that drives the load and
A motor control apparatus according to any one of claims 1 to 1 2,
Have,
The motor control device is a document reading device characterized in that it controls the driving of a motor that drives the load. An image forming unit that forms an image on a recording medium,
The motor that drives the load and
A motor control apparatus according to any one of claims 1 to 1 2,
Have,
The motor control device is an image forming device that controls the drive of a motor that drives the load.

Images