JP2018137932A - Motor control device, control method, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely suppress an increase in power supply voltage due to regenerative drive as compared with a prior art.SOLUTION: A motor control device 20 controlling a plurality of motors 3 connected to one power supply device 1B comprises: a vector control part 25 that controls vectors of the respective motors 3; a voltage increase detection part 212 that detects an increase in voltage V1 of the power supply device 1B due to regenerative drive of the motors 3; a selection part 214 that selects a motor 3 from the plurality of motors 3 according to a predetermined condition; and a current control command part 216 that, when the increase in voltage V1 of the power supply device 1B is detected by the voltage increase detection part 212, gives a command ΔId* to the vector control part 25 to cause a current to flow in the motor 3 selected by the selection part 214, the current to be consumed as heat inside the motor 3.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an electric motor control device, a control method, and an image forming apparatus.

  In image forming apparatuses such as copiers, printers, and facsimile machines, a permanent magnet synchronous motor (PMSM) is used as a drive source for rotating a roller that conveys paper.

  In general, a permanent magnet synchronous motor has a stator having a winding and a rotor using a permanent magnet, and an alternating current is passed through the winding to generate a rotating magnetic field, thereby rotating the rotor in synchronization therewith. . According to the vector control that controls the alternating current as a vector component in the dq coordinate system, it can be efficiently and smoothly rotated.

  When regenerative driving that generates torque in the direction opposite to the rotation direction is performed when the rotation is decelerated or stopped, the rotation can be decelerated or stopped earlier than when such torque is not generated.

  However, when regenerative driving is performed, the power supply voltage may rise due to the regenerative current flowing into the power supply. When the power supply voltage rises, the protection circuit for the power supply operates to stop the operation of the power supply or damage the circuit in the power supply.

  As a prior art for suppressing an increase in power supply voltage due to inflow of regenerative current, there is a technique described in Patent Document 1. Patent Document 1 discloses that the brake torque is controlled by adjusting the q-axis current and the regenerative energy is controlled by adjusting the d-axis current.

JP 2002-84780 A

  In the technique of Patent Document 1 described above, since there is an upper limit to the d-axis current that can be passed to the motor, the regenerative energy that raises the power supply voltage may not be consumed sufficiently as heat. There was a problem. For example, it is necessary to suppress the d-axis current amount so that the heat generated by the d-axis current is within a range that satisfies the heat resistance condition of the electric motor. In particular, when the motor is at a high temperature, the allowable amount of heat generation is small, so the upper limit value of the d-axis current at this time is small. Further, the upper limit of the d-axis current is determined by the allowable current amount of the drive circuit. Furthermore, for an electric motor that requires high accuracy in controlling the rotational speed, only a small d-axis current that does not affect the rotational speed can flow, and the regenerative energy cannot be consumed substantially.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electric motor control device and an electric motor control method that can more reliably suppress an increase in power supply voltage due to regenerative driving than before.

  An electric motor control device according to an embodiment of the present invention is an electric motor control device that controls a plurality of electric motors connected to a single power supply device, the vector control unit performing vector control of each of the electric motors, and the regenerative current of the electric motors A voltage rise detection unit that detects a voltage rise of the power supply device due to, a selection unit that selects a motor from a plurality of the motors according to a predetermined condition, and a voltage rise detection unit that increases the voltage of the power supply device A current control command unit that gives a command to the vector control unit to flow a current consumed as heat inside the motor to the motor selected by the selection unit.

  According to the present invention, an increase in power supply voltage due to regenerative driving can be suppressed more reliably than in the past.

1 is a diagram illustrating an outline of a configuration of an image forming apparatus including a motor control device according to an embodiment of the present invention. It is a figure which shows the outline | summary of a structure of a motor control apparatus. It is a figure which shows the example of a structure of a motor. It is a figure which shows four aspects of the drive of a motor. It is a figure which shows the dq axis | shaft model of a motor. It is a figure which shows the functional structure of the main control part in a motor control apparatus, and a drive / control circuit. It is a figure which shows the example of a structure of the drive part in a drive and control circuit, and a current detection part. It is a figure which shows the example of a structure of the vector control part in a drive / control circuit. It is a figure which shows the modification of the functional structure of a drive / control circuit. It is a figure which shows the flow of a process in a motor control apparatus.

  FIG. 1 shows an outline of the configuration of the image forming apparatus 1 including the motor control device 20 according to the embodiment of the present invention, and FIG. 2 shows an outline of the configuration of the motor control device 20.

  In FIG. 1, an image forming apparatus 1 is an electrophotographic color printer including a tandem printer engine 1A and a power supply device 1B that converts commercial alternating current into direct current.

  The printer engine 1A is configured around four imaging stations 4Y, 4M, 4C, and 4K for forming toner images. In the color printing mode, the four imaging stations 4Y, 4M, 4C, and 4K form toner images of four colors Y (yellow), M (magenta), C (cyan), and K (black) in parallel. To do. Each of the imaging stations 4Y, 4M, 4C, and 4K includes a cylindrical photosensitive member 5, a charging roller 6, a print head 7, a developing device 8, and the like.

  The toner images formed by the imaging stations 4Y to 4K are primarily transferred from the photoreceptor 5 to the transfer belt 16. The primarily transferred toner image is secondarily transferred at the nip portion of the secondary transfer roller 14 to the paper 2 that has been drawn from the paper cassette 10 by the paper feed roller 12 and conveyed through the registration roller 13. The sheet 2 on which the toner image is secondarily transferred passes through the inside of the fixing device 17. The fixing device 17 applies heat and pressure while conveying the paper 2 by the fixing rollers 17A and 17B. As a result, the toner image is fixed on the sheet 2. The sheet 2 that has passed through the fixing unit 17 is sent out to a sheet discharge tray 19 by a sheet discharge roller 18.

  The image forming apparatus 1 includes a plurality of brushless motors as a rotational drive source. For example, as shown in FIG. 2, the image forming apparatus 1 includes a paper feed motor 3a, a paper discharge motor 3b, a fixing motor 3c, photoconductor motors 3d, 3e, 3f, 3g, and a transfer body motor 3h.

  The paper feed motor 3 a drives the paper feed roller 12. The paper discharge motor 3 c drives the paper discharge roller 18. The fixing motor 3b drives the fixing rollers 17A and 17B. The photoreceptor motors 3d, 3e, 3f, and 3g drive the photoreceptors 5 of the corresponding imaging stations 4Y, 4M, 4C, and 4K, respectively. The transfer body motor 3h drives a roller around which the transfer belt 16 is wound.

  However, the drive system by the motor is not limited to this and can be variously different. For example, the photoconductor motors 3d, 3e, 3f, and 3g are individually provided in each of the imaging stations 4Y to 4K. However, the image forming apparatus is configured to be driven by one common motor, or the transfer belt 16 is shared by one motor. Various configurations are possible, such as a configuration in which the motor is driven by a single motor, or a configuration in which each of black and color is driven by one motor.

  In the following, the motors 3a to 3h may be referred to as “motor 3” as a whole or each without being distinguished.

  The plurality of motors 3 are controlled by the motor control device 20. The motor control device 20 includes a plurality of drive / control circuits 22a, 22b, 22c, 22d, 22e, 22f, 22g, and 22h, and commands to start (start) or stop rotation of these drive / control circuits 22a to 22h. And a main control unit 21 for providing

  Each of the drive / control circuits 22a to 22h performs vector control of the corresponding one motor 3. The plurality of motors 3 are connected to one power supply device 1B via drive / control circuits 22a to 22h. Hereinafter, the drive / control circuits 22a to 22h may be referred to as “drive / control circuit 22” as a whole or each without being distinguished.

  The main control unit 21 is a controller that controls the entire image forming apparatus 1 and includes a CPU (Central Processing Unit) that executes a control program and its peripheral devices. The main control unit 21 issues a command to the drive / control circuit 22 when the image forming apparatus 1 is warmed up, when a print job is executed, or when the image forming apparatus 1 is shifted to the power saving mode.

  FIG. 3 schematically shows an example of the configuration of the motor 3, and FIG. 4 schematically shows four modes of driving the motor 3.

  In FIG. 3, the motor 3 is a sensorless permanent magnet synchronous motor (PMSM). The motor 3 includes a stator 31 as an armature that generates a rotating magnetic field, and a rotor 32 using a permanent magnet. The stator 31 has U-phase, V-phase, and W-phase cores 36, 37, and 38 arranged at intervals of 120 degrees, and three windings (coils) 33, 34, and 35 that are Y-connected. A rotating magnetic field is generated by flowing a U-phase, V-phase, and W-phase AC current through the windings 33 to 35 and exciting the cores 36, 37, and 38 in order. The rotor 32 rotates in synchronization with this rotating magnetic field.

  In the example shown in FIG. 3, the number of magnetic poles of the rotor 32 is 2. However, the number of magnetic poles of the rotor 32 is not limited to 2, and may be 4, 6 or more. The rotor 32 may be an outer type or an inner type. Further, the number of slots of the stator 31 is not limited to three. In any case, the motor control device 20 performs vector control (sensorless vector control) for estimating the magnetic pole position and the rotational speed for the motor 3 using a control model based on the dq coordinate system. .

  Hereinafter, the rotation angle position of the N pole indicated by the black circle of the S pole and the N pole of the rotor 32 may be referred to as a “magnetic pole position PS” of the rotor 32.

  In FIG. 4, the motor speed control is divided into four modes (four-quadrant drive) based on the relationship between the motor speed direction (rotation direction) and the direction of torque generated by vector control. That is, for each of forward rotation (for example, CW) and reverse rotation (for example, CCW), a mode of powering drive in which the motor speed and the direction of torque match, and a mode of regenerative drive in which the two directions do not match There is.

  According to the regenerative drive, the motor 3 can be decelerated faster than in the case where the regenerative drive is not used. However, when regenerative driving is performed, depending on the state of other motors 3, a regenerative current generated by the motor 3 during regenerative driving may flow into the power supply device 1 </ b> B via the drive / control circuit 22. For example, when the current flowing from the power supply device 1B to the other motor 3 is small, the voltage (power supply voltage) in the power supply device 1B increases due to the inflow of the regenerative current. If the increase of the power supply voltage exceeds the upper limit of the allowable range, the circuit and load of the power supply device 1B are adversely affected and may be damaged in some cases.

  Therefore, the motor control device 20 is provided with a function of suppressing an increase in power supply voltage due to the inflow of regenerative current from the motor 2. Hereinafter, the configuration and operation of the image forming apparatus 1 will be described focusing on this function.

  FIG. 5 shows a dq axis model of the motor 3. In the vector control of the motor 3, the three-phase alternating current flowing through the windings 33 to 35 of the motor 3 is converted into a direct current flowing through the two-phase winding that rotates in synchronization with the permanent magnet that is the rotor 32. Simplify control.

  The magnetic flux direction (N-pole direction) of the permanent magnet is defined as the d-axis, and the direction advanced by π / 2 [rad] (90 °) in electrical angle from the d-axis is defined as the q-axis. The d axis and the q axis are model axes. The lead angle of the d-axis relative to the U-phase ridge line 33 is defined as θ. This angle θ represents the angular position of the magnetic pole (magnetic pole position PS) with respect to the U-phase winding 33. The dq coordinate system is at a position advanced by an angle θ with respect to the U-phase ridge line 33 as a reference.

  Since the motor 3 does not have a position sensor for detecting the angular position (magnetic pole position) of the rotor 32, the motor control device 20 estimates the magnetic pole position PS of the rotor 32, that is, the angle θ, and the estimated angle. The rotation of the rotor 32 is controlled using the estimated angle θm that is θ.

  Of the currents that flow through the windings 33 to 35, the q-axis component that flows in the q-axis direction is converted into torque in a direction that causes the motor 3 to rotate forward or reverse depending on the induced voltage constant. On the other hand, the d-axis component (d-axis current) flowing in the direction of the d-axis is not converted into torque but is consumed as heat in the windings 33 to 35.

  FIG. 6 shows functional configurations of the main control unit 21 and the drive / control circuit 22 in the motor control device 20. In FIG. 6, as a representative of the drive / control circuit 22, three drive / control circuits 22a, 22b, and 22c that respectively control the paper feed motor 3a, the paper discharge motor 3b, and the fixing motor 3c are depicted. The configurations of the drive / control circuits 22a, 22b and 22c are the same.

  The drive / control circuit 22 includes a drive unit 26 that drives the rotor 32 by passing a current through the windings 33 to 35 of the motor 3, a current detection unit 27 that detects a current flowing through the windings 33 to 35, and a drive unit 26. And a vector control unit 25 for controlling. And the vector control part 25 has the regeneration detection part 58 which detects whether the motor 3 which the said vector control part 25 controls is performing regeneration operation | movement.

  The main control unit 21 includes a speed command unit 210, a voltage increase detection unit 212, a motor selection unit 214, and a d-axis current control command unit 216 as components of the motor control device 20. These functions are realized by the hardware configuration of the main control unit 20 and when the control program is executed by the CPU.

  The speed command unit 210 gives a command value for the rotational speed of the motor 3 to each drive / control circuit 22. Specify the direction of rotation at startup.

  The voltage increase detection unit 212 detects an increase in the voltage of the power supply device 1 </ b> B due to the regenerative current of the motor 3. The voltage increase detection unit 212 receives the output voltage V1 of the power supply device 1B. The voltage increase detection unit 212 detects an increase in the voltage of the power supply device 1B based on the detection value of the output voltage V1. However, without detecting the output voltage V1, it is also possible to detect an increase in the voltage of the power supply device 1B based on the detected value of the current flowing in each motor 3 or the estimated value of the rotational speed of each motor 3 as described later. Is possible. In that case, data indicating the state in which the current or rotational speed of each motor 3 is in advance increases the voltage of the power supply device 1B based on an experiment or the like, and is stored. What is necessary is just to detect by determining whether it is in the state which shows.

  The voltage increase detection unit 212 has an increase amount with respect to a rated voltage value (for example, 24 volts) of the voltage value of the output voltage V1 or an increase rate in a detection cycle (for example, 1 ms) as a voltage increase of the power supply device 1B. The voltage change as described above is detected. For example, 10% of the rated voltage value is set as an increase amount threshold value, or 5% of the rated voltage value is set as an increase rate threshold value.

  The motor selection unit 214 selects a motor 3 that plays a role of consumption of regenerative current from a plurality of motors 3 according to a predetermined condition.

  As a selection condition, there is a priority order determined according to a load that is rotationally driven by a plurality of motors 3. In the photoconductor 5 and the transfer belt 16, disturbance in rotational speed tends to affect the image quality. For this reason, the photoreceptor motors 3d to 3g and the transfer body motor 3h that rotationally drive these loads are determined to have a low priority. The influence of the rotational speed disturbance in the paper feeding, fixing, and fixing is relatively small. Therefore, the paper feed motor 3a, the paper discharge motor 3b, and the fixing motor 3c are set in a high priority order. The motor selection unit 214 selects the motor 3 in descending order of priority.

  As a selection condition, it may be determined that the motor 3 is stopped. When there is a stopped motor 3, the motor selection unit 214 selects one or more motors 3 from the stopped motors 3.

  As a selection condition, the temperatures detected by the temperature sensors 70a, 70b, and 70c provided in the motors 3a, 3b, and 3c, respectively, can be determined. In this case, signals STa, STb, and STc indicating detected temperatures are input to the motor selection unit 214 from the temperature sensors 70a to 70c. The motor selection unit 214 selects the motor 3 in ascending order of temperature indicated by the signals STa to STc. The lower the temperature, the larger the current consumed as heat within the range satisfying the heat resistance constraint.

  The d-axis current control command unit 216 detects the increase in the voltage of the power supply device 1B by the voltage increase detection unit 213, and when any of the regeneration detection units 58 detects the regeneration operation, the d-axis current control command unit 216 A command is given to the vector control unit 25 so that a current consumed as heat flows. At that time, the d-axis current control command unit 216 determines the d-axis current increase command value ΔId * so that the d-axis current is increased more as the increase amount or the increase rate of the output voltage V1 of the power supply device 1B is larger. To the vector control unit 25.

  FIG. 7 shows an example of the configuration of the drive unit 26 and the current detection unit 27 in the drive / control circuit 22.

  The motor drive unit 26 is an inverter for driving the rotor 32 by causing a current to flow through the windings 33 to 35 of the motor 3. The motor drive unit 26 includes three dual elements 261, 262, and 263, a pre-drive circuit 265, and the like.

  Each of the dual elements 261 to 263 is a circuit component in which two transistors (for example, field effect transistors: FETs) with uniform characteristics are connected in series and housed in a package.

  The dual elements 261 to 263 control the current I flowing from the DC power supply line 211 to the ground line via the feeder lines 33 to 35. Specifically, the current Iu flowing through the winding 33 is controlled by the transistors Q1 and Q2 of the dual element 261, and the current Iv flowing through the winding 34 is controlled by the transistors Q3 and Q4 of the dual element 262. Then, the current Iw flowing through the winding 35 is controlled by the transistors Q5 and Q6 of the dual element 263.

  The predrive circuit 265 converts the control signals U +, U−, V +, V−, W +, and W− input from the vector control unit 25 into voltage levels suitable for the transistors Q1 to Q6. The converted control signals U +, U−, V +, V−, W +, W− are input to the control terminals (gates) of the transistors Q1 to Q6.

  The current detection unit 27 includes a U-phase current detection unit 271 and a V-phase current detection unit 272, and detects currents Iu and Iv flowing through the windings 33 and 34. Since Iu + Iv + Iw = 0, the current Iw can be obtained by calculation from the detected currents Iu and Iv. A W-phase current detection unit may be included.

  The U-phase current detection unit 271 and the V-phase current detection unit 272 amplify the voltage drop due to the shunt resistor inserted in the flow paths of the currents Iu and Iv, perform A / D conversion, and use them as detected values of the currents Iu and Iv. Output. That is, the two-shunt detection is performed. The resistance value of the shunt resistor is a small value on the order of 1 / 10Ω.

  FIG. 8 shows an example of the configuration of the vector control unit 25 in the drive / control circuit 22.

  The vector control unit 25 includes a speed control unit 51, a current control unit 52, an output coordinate conversion unit 53, a PWM conversion unit 54, an input coordinate conversion unit 55, a speed / position estimation unit 56, a voltage detection unit 57, and a regeneration detection unit 58. Have Each of these units performs the following processing when the d-axis current increase command value ΔId * from the d-axis current control command unit 216 is not given, that is, when the increase in the voltage of the power supply device 1B is not detected. Do.

  Based on the speed command value ω * from the speed command unit 210 and the speed estimate value ωm from the speed / position estimation unit 56, the speed control unit 51 d− so that the estimated speed value ωm approaches the speed command value ω *. Current command values Id * and Iq * in the q coordinate system are determined. The estimated speed value ωm is periodically input. The speed controller 51 determines the current command values Id * and Iq * each time the estimated speed value ωm is input.

  The current control unit 52 determines the voltage command values Vd * and Vq * of the dq coordinate system based on the current command values Id * and Iq *.

  Based on the estimated angle θm from the speed / position estimation unit 25 and the detected voltage value V1 from the voltage detection circuit 57, the output coordinate conversion unit 53 converts the voltage command values Vd * and Vq * into the U phase, the V phase, and the W phase. It is converted into phase voltage command values Vu *, Vv *, Vw *. That is, the voltage is converted from two phases to three phases.

  The PWM conversion unit 54 generates patterns of control signals U +, U−, V +, V−, W +, W− based on the voltage command values Vu *, Vv *, Vw * and outputs the patterns to the drive unit 26. The control signals U +, U−, V +, V−, W +, W− are signals for controlling the frequency and amplitude of the three-phase AC power supplied to the motor 3 by pulse width modulation (PWM). .

  The input coordinate conversion unit 55 calculates the value of the W-phase current Iw from each value of the U-phase current Iu and the V-phase current Iv detected by the current detection unit 27. Based on the estimated angle θm from the speed / position estimation unit 56 and the values of the three-phase currents Iu, Iv, Iw, the estimated current values Id, Iq of the dq axis coordinate system are calculated. That is, the current is converted from three phases to two phases.

  Based on the estimated current values Id and Iq from the input coordinate conversion unit 55 and the voltage command values Vd * and Vq * from the current control unit 52, the speed / position estimation unit 56 calculates the estimated speed value ωm according to a so-called voltage-current equation. Then, an estimated angle θm is obtained.

  The obtained speed estimation value ωm is output to the speed control unit 51. The obtained estimated angle θm is input to the output coordinate conversion unit 53 and the input coordinate conversion unit 55.

  The voltage detector 57 detects the output voltage V1 of the power supply device 1B.

  The regeneration detection unit 58 detects whether or not a regeneration operation is being performed based on at least one of the rotational speed of the motor 3 controlled by the vector control unit 25 and the current flowing through the motor 3. At that time, the estimated speed value ωm by the speed / position estimating unit 56 is used as the rotation speed of the motor 3, and the estimated current values Id and Iq by the input coordinate conversion unit 55 are used as the current flowing through the motor 3. When the regeneration detection unit 58 detects that a regeneration operation is being performed, the regeneration detection unit 58 notifies the d-axis current control command unit 216 to that effect.

  When the motor 3 controlled by the vector control unit 25 is selected by the motor selection unit 214 described above, the d-axis current increase command value ΔId * is supplied from the d-axis current control command unit 216 to the current control unit 52. Given to. In this case, the current control unit 52 adds the d-axis current increase command value ΔId * to the d-axis current command value Id * from the speed control unit 51, and the obtained value (Id * + ΔId *) and the speed control. The voltage command values Vd * and Vq * are determined based on the q-axis current command value Iq * from the unit 51.

  Based on the voltage command values Vd * and Vq * determined in this way, the voltage command values Vu *, Vv *, Vw * and the control signals U +, U−, V +, V−, W + as described above. , W− patterns are generated in order, and the motor 3 is driven by the drive unit 26.

  By adding the d-axis current increase command value ΔId *, the d-axis current flowing through the motor 3 increases. Accordingly, the regenerative current flowing into the power supply device 1B is canceled out by the current flowing out from the power supply device 1B. That is, the regenerative current flowing through one of the motors 3 is consumed as heat inside the motor 3. Therefore, the state in which the power supply voltage has increased returns to the rated voltage state. Even if the abnormality in the power supply voltage is not completely eliminated, at least a further increase in the power supply voltage is suppressed.

  FIG. 9 shows a modification of the functional configuration of the drive / control circuit 22. In this modification, the temperature of each motor 3 is estimated without using a temperature sensor.

  In the example of FIG. 9, the motor control device 20 b includes a main control unit 21 and a plurality of drive / control circuits 23 that respectively control the plurality of motors 3. In FIG. 9, as a representative of the drive / control circuit 23, three drive / control circuits 23a, 23b, and 23c for controlling the paper feed motor 3a, the paper discharge motor 3b, and the fixing motor 3c are depicted. The configuration of the drive / control circuits 23a, 23b, and 23c is the same. The configuration of the main control unit 21 is as described above.

  The drive / control circuit 23 includes a vector control unit 25 b, a drive unit 26, and a current detection unit 27. The configurations of the drive unit 26 and the current detection unit 27 are as described above (see FIG. 7).

  The vector control unit 25b includes a parameter estimation unit 61 and a temperature estimation unit 62 in addition to the components of the vector control unit 25 shown in FIG.

  The parameter estimation unit 61 estimates the parameter value of the motor 3 based on the current flowing through the motor 3. As the current flowing through the motor 3, the currents Iu and Iv detected by the current detection unit 27 are used. The parameter may be anything depending on the temperature. For example, there are resistance values of the windings 33 to 35 or induced voltage constants.

  The temperature estimator 62 estimates a temperature corresponding to the parameter value estimated by the parameter estimator 61 using a pre-stored lookup table or arithmetic expression that specifies the temperature corresponding to the parameter value. Then, signals STma, STmb, STmc indicating the estimated temperature are output.

  The signals STma, STmb, STmc are input to the motor selection unit 214 of the main control unit 21. The motor selection unit 214 takes in the temperatures indicated by the signals STma, STmb, STmc as the temperatures of the respective motors 3 and uses them for selection of the motors 3.

  FIG. 10 shows a processing flow in the motor control devices 20 and 20b.

  An increase in power supply voltage is detected (# 11). If the increase amount or rate of increase of the power supply voltage is less than the respective threshold value (NO in # 12), it is determined that it is not necessary to forcibly consume the regenerative current. In this case, the amount of increase in d-axis current (that is, d-axis current increase command value ΔId *) is set to zero (0) (# 13).

  If the increase amount or rate of increase of the power supply voltage is equal to or greater than the respective threshold value (YES in # 12), it is checked whether or not there is a motor 3 that is performing a regenerative operation. If there is no motor 3 in the regenerative operation (NO in # 14), the cause of the increase in the power supply voltage is not the inflow of the regenerative current, so the increase amount of the d-axis current is set to zero (# 13).

  If there is a motor 3 that is performing a regenerative operation (YES in # 14), the motor 3 that plays the role of consuming the regenerative current is selected (# 15). Then, the d-axis current passed through the selected motor 3 is increased (# 16).

  According to the above embodiment, even when it is difficult to consume the regenerative current as heat in the motor 3 during the regenerative operation, it can be consumed in the other motor 3. Therefore, an increase in power supply voltage due to regenerative driving can be suppressed more reliably than before.

  According to the above-described embodiment, the motor 3 is selected in the order of high priority determined in accordance with the target of the rotational drive and the d-axis current is increased. It is possible to prevent the d-axis current from increasing as much as possible. For example, the photoconductor motors 3d to 3f that require high rotation accuracy in order to improve the image quality are reduced in priority or removed from the options, so that the other motors 3 satisfy the requirement for rotation accuracy. Thus, the regenerative current can be consumed as heat.

  As a condition for selecting the motor 3 that assumes the role of consuming the regenerative current, priority order for satisfying the requirement of rotational accuracy, temperature, and stopping can be appropriately combined. For example, if there is a stopped motor 3, the motor 3 is selected. If there is no stopped motor 3, the temperature of the motors 3 whose priority is higher than a predetermined order is lower than the threshold is low. You can select in order. When the heat resistant temperatures are different among the plurality of motors 3, a motor having a high heat resistant temperature may be preferentially selected.

  In the above-described embodiment, the whole or each part of the image forming apparatus 1 and the motor control device 20, the method for detecting the rise of the power supply voltage V1, the criterion for determining whether or not it is raised (threshold value) ), Selection conditions of the motor 3, contents of processing, order, timing, etc. can be appropriately changed in accordance with the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1B Power supply device 2 Paper 3 Motor (electric motor 20 Motor control device (electric motor control device)
12 Paper feed roller (roller)
17A, 17B Fixing roller (roller)
18 Paper discharge roller (roller)
25, 25b Vector control unit 58 Regeneration detection unit 61 Parameter estimation unit 62 Temperature estimation unit 70 Temperature sensor 212 Voltage rise detection unit 214 Motor selection unit (selection unit)
216 d-axis current control command section (current control command section)
Id * current command value (current consumed as heat)
ΔId * d-axis current increase command value (command)
Iu, Iv current (detected value of current flowing in the motor)
V1 Voltage detection value (Power supply voltage detection value)
ωm Estimated speed (estimated rotational speed)

Claims (12)

An electric motor control device for controlling a plurality of electric motors connected to one power supply device,
A vector control unit for vector-controlling each of the electric motors;
A voltage increase detector that detects an increase in the voltage of the power supply device due to the regenerative current of the motor;
A selection unit that selects an electric motor from a plurality of the electric motors according to a predetermined condition;
The vector control unit causes a current consumed as heat inside the motor to flow to the electric motor selected by the selection unit when an increase in the voltage of the power supply device is detected by the voltage increase detection unit. A current control command section for giving a command to
An electric motor control device comprising: The current control command unit gives a command to increase the d-axis current in the vector control unit;
The electric motor control device according to claim 1. The voltage rise detection unit detects a voltage change in which an increase amount or an increase rate of a voltage value is equal to or greater than a respective threshold as a voltage rise of the power supply device,
The current control command unit gives the command to increase the increase amount of the d-axis current as the increase amount or the increase rate increases.
The electric motor control device according to claim 2. Each of the vector control units includes a regeneration detection unit that detects whether or not the electric motor controlled by the vector control unit is performing a regeneration operation.
The current control command unit gives a command to the vector control unit when an increase in voltage of the power supply device is detected and any of the regeneration detection units detects a regenerative operation;
The electric motor control device according to claim 1. The regenerative detection unit detects whether or not a regenerative operation is performed based on the rotation speed of the electric motor controlled by the vector control unit or the current flowing through the electric motor.
The electric motor control device according to claim 4. The voltage increase detection unit detects an increase in voltage of the power supply device based on a detection value of the voltage of the power supply device, a detection value of a current flowing through each electric motor, or an estimated value of the rotation speed of each electric motor. ,
The electric motor control device according to claim 1. The selection unit selects the electric motors in descending order of priority based on the priority order determined according to the load that is rotationally driven by the plurality of electric motors.
The electric motor control device according to claim 1. The selection unit selects an electric motor on the condition that it is stopped.
The electric motor control device according to claim 1. The selection unit selects the electric motors in ascending order of the temperature, with the temperatures detected by the temperature sensors respectively provided in the plurality of electric motors as the condition.
The electric motor control device according to claim 1. Each of the vector control units includes a parameter estimation unit that estimates a parameter of the motor based on a current flowing through the motor, and a temperature estimation unit that estimates the temperature of the motor based on the estimated parameter. ,
The selection unit selects an electric motor in order of increasing temperature with the temperature estimated by the temperature estimation unit as the condition.
The electric motor control device according to claim 1. An image forming apparatus for forming an image on paper,
A plurality of electric motors;
A power supply device to which the plurality of electric motors are connected;
A plurality of rollers that are respectively driven to rotate by the electric motor to convey the paper;
An electric motor control device for controlling the plurality of electric motors,
The motor controller is
A vector control unit for vector-controlling each of the electric motors;
A voltage increase detector that detects an increase in the voltage of the power supply device due to the regenerative current of the motor;
A selection unit for selecting an electric motor from the plurality of electric motors according to a predetermined condition;
The vector control unit causes a current consumed as heat inside the motor to flow to the electric motor selected by the selection unit when an increase in the voltage of the power supply device is detected by the voltage increase detection unit. A current control command section for giving a command to
An image forming apparatus. An electric motor control method for vector-controlling each of a plurality of electric motors connected to one power supply device,
When an increase in the voltage of the power supply device due to the regenerative current of the motor is detected, one or more motors are selected from the plurality of motors according to a predetermined condition, and a d-axis current that flows to the selected motors is selected. increase,
An electric motor control method.

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