CN215912055U - Motor control device, motor unit - Google Patents
Motor control device, motor unit Download PDFInfo
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- CN215912055U CN215912055U CN202120349202.2U CN202120349202U CN215912055U CN 215912055 U CN215912055 U CN 215912055U CN 202120349202 U CN202120349202 U CN 202120349202U CN 215912055 U CN215912055 U CN 215912055U
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Abstract
The utility model provides a motor control device and a motor unit. A motor control device for controlling a motor includes a voltage detection unit, a rotation speed detection unit, and a detection control unit. The voltage detection unit detects an induced voltage generated in a stator coil of the motor and outputs a detection signal indicating a value of the induced voltage. The rotation speed detection unit detects the rotation speed of the motor based on the detection signal. The detection control unit controls the voltage detection unit. The voltage detection unit includes a ratio change unit capable of changing a ratio of a voltage level of the detection signal to the induced voltage. The detection control unit controls the ratio changing unit according to the rotation speed.
Description
Technical Field
The utility model relates to a motor control device and a motor unit.
Background
Conventionally, there is known a device that divides an induced voltage generated in a stator coil of a motor by a voltage dividing circuit and detects a rotational position of the motor based on a divided voltage value. In this device, for example, a detection signal indicating a divided voltage value corresponding to the induced voltage is converted into a digital signal (see japanese unexamined patent publication No. h 11-69867).
In this apparatus, when the ratio of the voltage level of the detection signal to the induced voltage is increased, the voltage level of the detection signal becomes larger, and the detection accuracy of the induced voltage becomes higher. Therefore, the detection accuracy of the rotational position of the motor becomes higher. Therefore, when the motor is started or the rotation speed of the motor is low, the induced voltage is low, and therefore, it is preferable that the ratio is large.
However, the induced voltage of the stator coil becomes high in accordance with the rotation speed of the motor. Therefore, if the above ratio is set to a large value suitable for a case where the rotation speed of the motor is low, the induced voltage becomes higher as the rotation speed of the motor becomes higher, and therefore the voltage level of the detection signal becomes higher. In this case, there is a possibility that a problem occurs in a circuit at a subsequent stage of the voltage dividing circuit. For example, the voltage level of the detection signal may exceed the input rated voltage of the circuit at the subsequent stage, and the driving of the motor may be affected. On the other hand, if the above ratio is set to a small value suitable for a case where the rotation speed of the motor is high, the detection accuracy of the induced voltage is low at the time of starting the motor or in a case where the rotation speed of the motor is low. Therefore, it may be difficult to stably drive the motor.
SUMMERY OF THE UTILITY MODEL
The purpose of the present invention is to stably drive a motor without being affected by the rotational speed of the motor.
The utility model relates to a motor control device, it controls the motor, its characterized in that, motor control device has: a voltage detection unit that detects an induced voltage generated in a stator coil of the motor and outputs a detection signal indicating a value of the induced voltage; a rotation speed detecting unit that detects a rotation speed of the motor based on the detection signal; and a detection control unit that controls the voltage detection unit, wherein the voltage detection unit has a ratio changing unit that can change a ratio of a voltage level of the detection signal to the induced voltage, and the detection control unit controls the ratio changing unit in accordance with the rotation speed.
The motor control device according to claim 2 is characterized in that the voltage detection unit further includes a 1 st resistor, a 2 nd resistor, and a 3 rd resistor, the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio change unit form a voltage dividing circuit for detecting the induced voltage, one end of the 1 st resistor is connected to the stator coil, the 2 nd resistor is connected to the other end of the 1 st resistor and connected in parallel to the ratio change unit and the 3 rd resistor, the 3 rd resistor is connected to the other end of the 1 st resistor and connected in series to the ratio change unit, and the ratio change unit switches between a conduction state and a non-conduction state of the 3 rd resistor according to a switching signal output from the detection control unit.
The motor control device of utility model No. 1 is characterized in that the voltage detecting section further has a 1 st resistor, a 2 nd resistor and a 3 rd resistor, the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio changing part form a voltage dividing circuit that detects the induced voltage, one end of the 1 st resistor is connected to the stator coil, the 2 nd resistor is connected to the other end of the 1 st resistor, and connected in parallel with the ratio changing unit and the 3 rd resistor, the 3 rd resistor being connected to the other end of the 1 st resistor, and a ratio changing unit connected in series to the ratio changing unit, the ratio changing unit switching between a conductive state and a non-conductive state of the 3 rd resistor in accordance with a switching signal output from the detection control unit, a resistance value of the 3 rd resistor being larger than a resistance value of the 2 nd resistor.
The motor control device according to claim 4 is the motor control device according to claim 1, wherein the voltage detection unit further includes a 1 st resistor, a 2 nd resistor, and a 3 rd resistor, the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio change unit form a voltage dividing circuit that detects the induced voltage, one end of the 1 st resistor is connected to the stator coil, the 2 nd resistor is connected to the other end of the 1 st resistor and connected in parallel to the ratio change unit and the 3 rd resistor, the 3 rd resistor is connected to the other end of the 1 st resistor and connected in series to the ratio change unit, the ratio change unit switches conduction and non-conduction states of the 3 rd resistor according to a switching signal output from the detection control unit, and the ratio change unit includes a field effect transistor.
The motor control device of claim 5 is the motor control device of claim 1, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: decreasing the ratio according to an increase in the rotational speed, and increasing the ratio according to a decrease in the rotational speed.
The motor control device according to any one of claims 1 to 4, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the ratio is decreased when the rotation speed increases and exceeds a threshold value, and the ratio is increased when the rotation speed decreases and falls below the threshold value, the threshold value being a value within the predetermined range.
The motor control device of utility model 7 is the motor control device of utility model 1, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the detection control unit performs control to decrease the ratio when the rotation speed increases and exceeds a threshold, increase the ratio when the rotation speed decreases and falls below the threshold, and perform control to: the ratio is decreased when the rotation speed increases and exceeds the other threshold value, and the ratio is increased when the rotation speed decreases and falls below the other threshold value, the threshold value being one value within the predetermined range, and the other threshold value being one value within the predetermined range and being a value different from the threshold value.
The motor control device of claim 8 is the motor control device of claim 1, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the detection control unit performs control such that the ratio is decreased when a 1 st elapsed time during which the rotation speed is continuously equal to or greater than a threshold value reaches a 1 st period from a time point at which the rotation speed becomes equal to or greater than the threshold value, and the ratio is increased when a 2 nd elapsed time during which the rotation speed is continuously less than the threshold value reaches a 2 nd period from a time point at which the rotation speed becomes less than the threshold value, and the detection control unit performs control such that: the ratio is decreased when the rotation speed increases and exceeds the other threshold value, and the ratio is increased when the rotation speed decreases and falls below the other threshold value, the threshold value being one value within the predetermined range, and the other threshold value being one value within the predetermined range and being a value different from the threshold value.
In the motor control device according to any one of claims 1 to 4, the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the ratio is decreased when the rotation speed is equal to or higher than an upper threshold value, and the ratio is increased when the rotation speed is lower than a lower threshold value, the upper threshold value and the lower threshold value each being one value within the predetermined range, and the upper threshold value being larger than the lower threshold value.
The motor control device of claim 10 is the motor control device of claim 1, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the ratio is decreased when a 1 st elapsed time, during which the rotational speed is continuously equal to or greater than the upper threshold, reaches a 1 st period from a time when the rotational speed is equal to or greater than the upper threshold, and the ratio is increased when a 2 nd elapsed time, during which the rotational speed is continuously less than the lower threshold, reaches a 2 nd period from a time when the rotational speed becomes less than a lower threshold, the upper threshold and the lower threshold each being one value within the predetermined range, and the upper threshold being greater than the lower threshold.
The motor control device according to claim 11 is the motor control device according to claim 4, wherein the detection control unit performs the following control when the rotation speed takes an arbitrary value within a predetermined range: the detection control portion performs the following control in accordance with an increase in the rotation speed to decrease the ratio, and in accordance with a decrease in the rotation speed to increase the ratio: the ratio is decreased when a 1 st elapsed time, during which the rotational speed is continuously equal to or greater than the upper threshold, reaches a 1 st period from a time when the rotational speed is equal to or greater than the upper threshold, and the ratio is increased when a 2 nd elapsed time, during which the rotational speed is continuously less than the lower threshold, reaches a 2 nd period from a time when the rotational speed becomes less than a lower threshold, the upper threshold and the lower threshold each being one value within the predetermined range, and the upper threshold being greater than the lower threshold.
The motor control device of claim 12 is the motor control device of claim 6, characterized in that the motor control device further has a signal conversion unit that converts the detection signal into a pulse signal and outputs the pulse signal to the rotation speed detection unit.
The utility model relates to a motor unit, its characterized in that, this motor unit has: the motor control device according to any one of utility model nos. 1 to 11; and a motor controlled by the motor control device, the motor including: a rotor rotatable about a central axis; and a stator that drives the rotor, wherein one end of a stator coil of the stator is connected to the motor control device.
According to the exemplary motor control device of the present invention, the motor can be stably driven without being affected by the rotation speed of the motor. Further, according to the motor unit including the motor control device described above, the motor can be stably driven without being affected by the rotation speed of the motor.
The above and other features, elements, steps, features and advantages of the present invention will be more clearly understood from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.
Drawings
Fig. 1 is a schematic diagram showing a configuration example of a motor unit.
Fig. 2 is a flowchart for explaining a control example of the motor control device related to the voltage detection unit.
Fig. 3A is a graph showing an example of control of the motor control device related to the voltage detection unit.
Fig. 3B is a graph in which the vicinity of the time of change of the ratio of the rotation speed in the rising trend is enlarged.
Fig. 3C is a graph in which the vicinity of the changing timing of the ratio of the rotation speed in the downward trend is enlarged.
Fig. 4 is a schematic diagram showing a configuration example of the voltage detection unit in modification 1.
Fig. 5 is a flowchart for explaining a control example in the 1 st modification of the motor control device related to the voltage detection unit.
Fig. 6 is a graph showing a control example in the 1 st modification of the motor control device relating to the voltage detection unit.
Fig. 7 is a flowchart for explaining a control example in the 2 nd modification of the motor control device related to the voltage detection unit.
Fig. 8 is a graph showing a control example in the 2 nd modification of the motor control device relating to the voltage detection unit.
Fig. 9 is a schematic diagram showing a configuration example of the voltage detection unit in modification 3.
Detailed Description
Hereinafter, exemplary embodiments will be described with reference to the drawings.
< 1. embodiment >
Fig. 1 is a schematic diagram showing a configuration example of a motor unit 100. The motor unit 100 is mounted on, for example, an air blower of a household electrical appliance such as a hair dryer. However, the use of the motor unit 100 is not limited to this example.
As shown in fig. 1, the motor unit 100 has a motor 1 and a motor control device 2. The motor 1 is controlled by a motor control device 2. Further, the motor unit 100 is connected to a dc power supply 500. The dc power supply 500 supplies dc power to the motor unit 100. The positive output terminal of the dc power supply 500 is connected to the motor control device 2, and the negative output terminal is grounded.
< 1-1. Motor >
The motor 1 has a rotor 11 and a stator 12. The rotor 11 is rotatable about a central axis (not shown) with respect to the stator 12. A magnet is disposed on the rotor 11. The stator 12 drives the rotor 11 to rotate when the motor 1 is driven. Stator 12 includes U-phase stator coil 121U, V-phase stator coil 121V, and W-phase stator coil 121W. In the following, the stator coil 121u, the stator coil 121v, and the stator coil 121w of each phase may be collectively referred to as "stator coil 121". For example, the stator 12 includes a stator core (not shown) as a magnetic body and a stator coil 121 formed by winding a lead wire around the stator core. In the present embodiment, one end of each stator coil 121 is star-connected with a neutral point 121n as a center. The other end of stator coil 121 opposite to neutral point 121n is connected to motor control device 2. However, a delta connection connecting one end and one end of each stator coil 121 to each other may be employed instead of the star connection.
< 1-2. Motor control device
The motor control device 2 controls the motor 1. The motor control device 2 includes an inverter 21, a voltage detection unit 22, a signal conversion unit 23, a storage unit 24, and a control unit 25.
The inverter 21 supplies three-phase ac power to the motor 1. The inverter 21 has a power conversion unit 211. The high-voltage side end of the power conversion unit 211 is connected to the positive output terminal of the dc power supply 500. The low-voltage side end of the power conversion portion 211 is grounded. The power conversion unit 211 converts the dc power supplied from the dc power supply 500 into three-phase ac power and supplies the three-phase ac power to the motor 1. The power conversion operation of the power conversion unit 211 is controlled by the drive signals Pu, Pv, Pw, Px, Py, and Pz output from the control unit 25.
The voltage detection unit 22 detects an induced voltage Vi generated in the stator coil 121 of the motor 1, and outputs a detection signal Sd indicating the value of the induced voltage Vi. As described above, the motor control device 2 includes the voltage detection unit 22. For example, the voltage detection unit 22 generates a detection signal Sd and outputs the detection signal Sd to the signal conversion unit 23. The voltage level Vd of the detection signal Sd is a value obtained by multiplying the value of the induced voltage Vi by a ratio r described later. The voltage detection unit 22 will be described in detail later.
The signal conversion section 23 converts the detection signal Sd into a rectangular wave signal Sp and outputs the rectangular wave signal Sp to the control unit 25. In the present embodiment, the signal conversion unit 23 is a comparator. The comparator compares a voltage level Vd of the detection signal Sd with a reference voltage level. For example, if the voltage level Vd of the detection signal Sd is equal to or greater than the reference voltage level, the comparator outputs the signal Sp at a high level, and if the voltage level Vd of the detection signal Sd is less than the reference voltage level, the comparator outputs the signal Sp at a low level. Thereby, the signal conversion unit 23 converts the detection signal Sd into a pulse signal, and outputs the pulse signal to the rotation speed detection unit 251. Since the processing steps in the control unit 25 can be reduced by converting the detection signal Sd into a pulse signal, the processing speed of the pulse signal based on the rotation speed Nr in the rotation speed detection unit 251 can be increased. The pulse signal is a binarized signal, and thus can be used as a digital signal. In addition, the signal conversion unit 23 is not limited to this example, and may be an a/D converter. The a/D converter converts the analog detection signal Sd into a digital signal and outputs the digital signal to the rotation speed detection unit 251.
In the present embodiment, the signal conversion unit 23 is a functional component of a microcomputer mounted on the motor control device 2. However, the signal conversion section 23 is not limited to this example, and may be a physical structure section such as a circuit, a device, or an element.
The storage unit 24 is a non-transitory storage medium that maintains storage even when supply of power supply power is stopped. The storage unit 24 stores, for example, a program and information used in a microcomputer and a control unit 25 mounted on the motor control device 2.
The control unit 25 controls each component of the motor control device 2. The control unit 25 controls the inverter 21 based on the speed command signal So and the rectangular wave signal Sp to drive the motor 1. The speed command signal So is a signal indicating the target rotation speed N0, and is input from the outside of the motor control device 2 in the present embodiment.
In the present embodiment, the control unit 25 is a microcomputer different from the signal conversion section 23. However, the present invention is not limited to this example, and the control unit 25 and the signal conversion unit 23 may be different functional components of the same microcomputer.
The control unit 25 includes a rotation speed detection unit 251, a motor control unit 252, and a detection control unit 253. The rotation speed detection unit 251, the motor control unit 252, and the detection control unit 253 are functional components of a microcomputer mounted on the motor control device 2. However, the present invention is not limited to this example, and at least one of them may be a physical structure portion such as a circuit, a device, or an element.
The rotation speed detection unit 251 detects the rotation speed Nr of the motor 1 based on the detection signal Sd. The motor control device 2 includes a rotation speed detecting unit 251. More specifically, the rotation speed detection unit 251 estimates the rotation speed Nr, the rotation angle position, and the like of the motor 1 from the rectangular wave signal Sp converted from the detection signal Sd.
The motor control unit 252 outputs drive signals Pu, Pv, Pw, Px, Py, and Pz of the motor 1 according to the rotation speed Nr. The motor control device 2 includes a motor control unit 252. More specifically, the motor control unit 252 compares the speed command signal So with the detection result of the rotation speed detection unit 251. Then, the motor control unit 252 generates the drive signals Pu, Pv, Pw, Px, Py, and Pz and outputs the drive signals to the inverter 21 so that the rotation speed Nr of the motor 1 reaches the target rotation speed N0. The drive signals Pu, Pv, Pw, Px, Py, and Pz are PWM pulses. The motor control unit 252 PWM-controls the power conversion unit 211 of the inverter 21 by the drive signals Pu, Pv, Pw, Px, Py, and Pz. Thereby, the motor control unit 252 controls the rotational driving of the motor 1.
The detection control unit 253 controls the voltage detection unit 22. The motor control device 2 includes a detection control unit 253. For example, the detection control unit 253 generates the switching signal Ss based on the detection result of the rotation speed detection unit 251 and outputs the switching signal Ss to the voltage detection unit 22. The switching signal Ss is a control signal of the voltage detection section 22. Detection control unit 253 changes ratio r of voltage level Vd of detection signal Sd output from voltage detection unit 22 to induced voltage Vi by outputting switching signal Ss to voltage detection unit 22.
< 1-3. Voltage detection part >
Next, the details of the voltage detection unit 22 will be described with reference to fig. 1. As shown in fig. 1, the voltage detection unit 22 includes a U-phase voltage detection unit 22U, a V-phase voltage detection unit 22V, and a W-phase voltage detection unit 22W. The switching signal Ss output from the detection control unit 253 includes a switching signal Su input to the U-phase voltage detection unit 22U, a switching signal Sv input to the V-phase voltage detection unit 22V, and a switching signal Sw input to the W-phase voltage detection unit 22W.
The U-phase voltage detection unit 22U is connected to the end of the U-phase stator coil 121U opposite to the neutral point 121 n. The U-phase voltage detecting unit 22U detects the induced voltage Viu generated in the U-phase stator coil 121U when the motor 1 rotates, and outputs a U-phase detection signal indicating the detection result to the signal converting unit 23. The voltage level of the detection signal of the U-phase is a value (ru × Viu) obtained by multiplying the value of the induced voltage Viu by the ratio ru. The ratio ru is changed in accordance with a switching signal Su for the U phase included in the switching signal Ss.
V-phase voltage detection unit 22V is connected to the end of V-phase stator coil 121V opposite to neutral point 121 n. The V-phase voltage detection unit 22V detects an induced voltage Viv generated in the V-phase stator coil 121V when the motor 1 rotates, and outputs a V-phase detection signal indicating the detection result to the signal conversion unit 23. The voltage level of the detection signal of the V phase is a value (rv × Viv) obtained by multiplying the value of the induced voltage Viv by the ratio rv. The ratio rv is changed in accordance with a switching signal Sv for the V phase included in the switching signal Ss.
W-phase voltage detection unit 22W is connected to ends of W-phase stator coil 121W opposite to neutral point 121 n. The W-phase voltage detection unit 22W detects an induced voltage Viw generated in the W-phase stator coil 121W when the motor 1 rotates, and outputs a W-phase detection signal indicating the detection result to the signal conversion unit 23. The voltage level of the detection signal of the W phase is a value (rw × Viw) obtained by multiplying the value of the induced voltage Viw by the ratio rw. The ratio rw is changed in accordance with a switching signal Sw for the W phase included in the switching signal Ss.
The U-phase voltage detection unit 22U, the V-phase voltage detection unit 22V, and the W-phase voltage detection unit 22W have the same configuration. Hereinafter, the detection signal of the U-phase, the detection signal of the V-phase, and the detection signal of the W-phase are collectively referred to as "detection signal Sd". The ratio ru for the U-phase induced voltage Viu, the ratio rv for the V-phase induced voltage Viv, and the ratio rw for the W-phase induced voltage Viw are collectively referred to as "ratio r".
Next, the structure of the voltage detection unit 22 of the present embodiment will be explained. The voltage detector 22 includes a ratio changing unit 221, a 1 st resistor R1, a 2 nd resistor R2, a 3 rd resistor R3, and a filter circuit F.
More specifically, by the control of the ratio changing unit 221 according to the rotation speed Nr, the ratio r between the voltage level Vd of the detection signal Sd and the induced voltage Vi is further decreased when the rotation speed Nr is high, and the ratio r is increased when the rotation speed Nr is low. That is, when the rotation speed Nr takes an arbitrary value within a predetermined range, the following control is performed: the ratio r is decreased according to an increase in the rotation speed Nr, and is increased according to a decrease in the rotation speed Nr. When the rotation speed Nr is high, the detection control unit 253 further decreases the ratio r, thereby suppressing the rise of the voltage level Vd of the detection signal Sd. By preventing the voltage level Vd from reaching the maximum rated voltage Vrm of the signal conversion unit 23 at the subsequent stage, the signal conversion unit 23 can be electrically protected. On the other hand, the detection accuracy of the induced voltage Vi is worse than the case of increasing the ratio r. However, since the voltage level of induced voltage Vi is high when rotation speed Nr is high, the proportion of the noise voltage to induced voltage Vi is small even if a noise voltage having a small voltage level is applied to detection control unit 253.
Further, by further increasing the ratio r by detection control unit 253 when the rotation speed Nr is low, the detection accuracy of induced voltage Vi can be further improved when motor 1 is started or when rotation speed Nr is low. When the rotation speed Nr is low, the voltage level of the induced voltage Vi is low, and therefore, if a noise voltage having a small voltage level is applied to the detection control unit 253, the proportion of the noise voltage to the induced voltage Vi is large. Therefore, it is necessary to improve the detection accuracy of the induced voltage Vi required for the rotation control. This enables the motor 1 to be stably driven when the motor 1 is started and when the motor 1 is driven from low-speed rotation to high-speed rotation.
The 1 st resistor R1, the 2 nd resistor R2, and the 3 rd resistor R3 are resistance elements. The 1 st resistor R1, the 2 nd resistor R2, the 3 rd resistor R3, and the ratio changing unit 221 form a voltage dividing circuit that detects the induced voltage Vi. One end of the 1 st resistor R1 is connected to the stator coil 121. The 2 nd resistor R2 is connected to the other end of the 1 st resistor R1. In this embodiment, one end of the 2 nd resistor R2 is connected to the other end of the 1 st resistor R1, and the other end of the 2 nd resistor R2 is grounded. Further, the 2 nd resistor R2 is connected in parallel to the ratio changing unit 221 and the 3 rd resistor R3. The 3 rd resistor R3 is connected to the other end of the 1 st resistor R1 and is connected in series to the ratio changing unit 221. For example, one end of the 3 rd resistor R3 is connected to the other end of the 1 st resistor R1. The other end of the 3 rd resistor R3 is connected to one end of the ratio changing unit 221. The other end of the ratio changing unit 221 is grounded.
The voltage divider circuit is connected to the signal converter 23 via the filter circuit F. The filter circuit F removes an electrical noise of the detection signal Sd representing the voltage division value of the voltage division circuit. For example, the filter circuit F removes noise from a carrier signal used in PWM control of the inverter 21. The input terminal of the filter circuit F is connected between the 1 st resistor R1 and the 2 nd resistor R2 and between the 1 st resistor R1 and the 3 rd resistor R3. The output terminal of the filter circuit F is connected to the signal conversion unit 23.
In the present embodiment, the ratio changing unit 221 switches the conduction state and the non-conduction state of the 3 rd resistor R3 in accordance with the switching signal Ss output from the detection control unit 253. In the present embodiment, the ratio changing unit 221 is switched on and off in accordance with the switching signal Ss. When the ratio changing unit 221 is turned on by the switching signal Ss, the 3 rd resistor R3 is turned on. When the ratio changing unit 221 is turned off by the switching signal Ss, the 3 rd resistor R3 is in a non-conducting state.
The voltage detection unit 22 of the present embodiment can provide the motor control device 2 at a low cost by configuring the voltage dividing circuit using a low-cost resistance element.
Preferably, the resistance value of the 3 rd resistor R3 is greater than the resistance value of the 2 nd resistor R2. In this embodiment, the resistance of the 2 nd resistor R2 is, for example, 51 k Ω, and the resistance of the 3 rd resistor R3 is, for example, 100 k Ω. In this way, it is possible to prevent the combined resistance value of the 2 nd resistor R2 and the 3 rd resistor R3 from being excessively lowered by switching the 3 rd resistor R3 to the on state. Therefore, the voltage dividing value of the voltage dividing circuit can be prevented from being excessively changed before and after switching. That is, since the ratio r of the voltage level Vd of the detection signal Sd output by the voltage detection unit 22 to the induced voltage Vi can be prevented from being excessively changed, the ratio r can be easily changed more appropriately.
In the present embodiment, the ratio changing unit 221 is a field effect transistor. A field effect Transistor has a faster operation response than a Bipolar Transistor, an IGBT (Insulated Gate Bipolar Transistor), or the like, and thus is easy to control and has less power loss. However, the present invention is not limited to this example, and other switching elements such as bipolar transistors and IGBTs may be used as ratio changing unit 221.
< 1-4. example of operation of Motor control device
Next, the control of the motor control device 2 related to the voltage detection unit 22 will be described with reference to fig. 2 to 3C. Fig. 2 is a flowchart for explaining a control example of the motor control device 2 related to the voltage detection unit 22. Fig. 3A is a graph showing an example of control of the motor control device related to the voltage detection unit 22. Fig. 3B is a graph in which the vicinity of the time when the ratio r of the rotation speed Nr which is in the rising trend is changed is enlarged. Fig. 3C is a graph in which the vicinity of the time when the ratio r of the rotation speed Nr which is in the downward trend is changed is enlarged. In the upper graph of fig. 3A, a solid line Nr represents the rotation speed Nr of the motor 1. In the lower graph of fig. 3A, a solid line Vd indicates the voltage level of the detection signal Sd changed according to the flowchart of fig. 2. The broken line Vr1 indicates a voltage level (r1 × Vi) when the 1 st ratio r1 is multiplied by the induced voltage Vi. The broken line Vr2 indicates a voltage level (r2 × Vi) when the induced voltage Vi is multiplied by the 2 nd ratio r2 smaller than the 1 st ratio r 1. In fig. 3B and 3C, the alternate long and short dash line indicates the rising and falling tendency of the rotation speed Nr of the motor 1.
The flowchart of fig. 2 starts when the motor 1 is started, for example, and ends when the motor 1 is stopped. At the start of the flowchart of fig. 2, the ratio changing unit 221 is turned off.
First, the detection controller 253 determines whether or not the rotation speed Nr of the motor 1 is equal to or greater than a threshold value Ns (step S101).
If Ns is determined to be equal to or less than Nr (yes in step S101), the detection controller 253 determines whether or not the 1 st elapsed time has reached the 1 st period T1 (step S102). In the present embodiment, the 1 st elapsed time is a period during which the rotation speed Nr is continuously equal to or greater than the threshold Ns from the time tu at which the rotation speed Nr is equal to or greater than the threshold Ns.
If it is not determined that the 1 st elapsed time has reached the 1 st period T1 (no in step S102), the flowchart of fig. 2 returns to step S101.
When determining that the 1 st elapsed time has reached the 1 st period T1 (yes in step S102), the detection controller 253 turns on the ratio changer 221 (step S103). Thereby, the ratio r of the voltage level Vd of the detection signal Sd to the induced voltage Vi becomes the 1 st ratio r1 smaller. Then, the flowchart of fig. 2 returns to step S101.
On the other hand, if Ns is not determined to be equal to or less than Nr (no in step S101), the detection controller 253 determines whether or not the 2 nd elapsed time has reached the 2 nd period T2 (step S104). In the present embodiment, the 2 nd elapsed time is a period during which the rotation speed Nr is continuously less than the threshold Ns from the time td at which the rotation speed Nr becomes less than the threshold Ns.
If it is not determined that the 2 nd elapsed time has reached the 2 nd period T2 (no in step S104), the flowchart of fig. 2 returns to step S101.
When determining that the 2 nd elapsed time has reached the 2 nd period T2 (yes in step S104), the detection controller 253 turns off the ratio changer 221 (step S105). Thereby, the ratio r becomes a larger 2 nd ratio r 2. Then, the flowchart of fig. 2 returns to step S101.
In the flowchart of fig. 2, at least one of steps S102 and S104 may be omitted. When step S102 is omitted, the flowchart of fig. 2 proceeds to step S103 in the case where step S101 is yes. That is, if the rotation speed Nr of the motor 1 is equal to or greater than the threshold value Ns, the ratio changing unit 221 is turned on, and the ratio r becomes the 1 st ratio r1 which is smaller. When step S104 is omitted, the flowchart of fig. 2 proceeds to step S105 when step S101 is no. That is, if the rotation speed Nr of the motor 1 is smaller than the threshold Ns, the ratio changing unit 221 is turned off, and the ratio r becomes the 2 nd ratio r2 which is larger.
In the above-described processing, the detection controller 253 performs the following control: when the rotation speed Nr increases and exceeds the threshold Ns, the ratio r is decreased, and when the rotation speed Nr decreases and falls below the threshold Ns, the ratio r is increased. The threshold value Ns is a value within the above-described predetermined range. In this way, the ratio r of the voltage level Vd of the detection signal Sd to the induced voltage Vi can be changed with a simple configuration.
As a specific example, control of the motor unit 100 mounted on the blower device provided in the blower used at a plurality of different rotation speeds Na and Nb (> Na) will be described. In this case, Na < Ns < Nb can be assumed. The threshold Ns is preferably a value distant from the rotation speeds Na and Nb, and may be, for example, an intermediate value { (Na + Nb)/2} between them. In this way, since the threshold Ns is a value distant from the actually used rotation speeds Na and Nb, it is possible to suppress the ratio r from being frequently changed in accordance with the fluctuation of the rotation speed Nr.
A plurality of threshold values for the switching ratio r may be set. In the above-described hair dryer, when the threshold value Ns and the other threshold value Ns2 are set, the detection control unit 253 decreases the ratio r when the rotation speed Nr increases and exceeds the threshold value Ns. When the rotation speed Nr increases and exceeds the other threshold Ns2, the ratio r is also decreased. Further, the detection controller 253 increases the ratio r when the rotation speed Nr decreases below the other threshold Ns2 with respect to at least one other threshold Ns 2. When the rotation speed Nr further decreases to be lower than the threshold value Ns, the ratio r is also increased. In addition, in this case, Na < Ns2< Nb. As Ns or Ns2, various values can be selected depending on the situation, but any value between Na and Nb is used. Thus, the threshold value must be selected from a range of values. In the present application, such a numerical range may be referred to as a predetermined range.
Further, when the 1 st elapsed time during which the rotation speed Nr is continuously equal to or greater than the threshold value Ns reaches the 1 st period T1 from the time tu at which the rotation speed Nr is equal to or greater than the threshold value Ns, the detection control unit 253 further decreases the ratio r. When the 2 nd elapsed time during which the rotation speed Nr is continuously smaller than the threshold value Ns reaches the 2 nd period T2 from the time td at which the rotation speed Nr becomes smaller than the threshold value Ns, the detection control portion 253 further increases the ratio r. That is, the detection controller 253 performs the following control: when the 1 st elapsed time during which the rotation speed Nr continuously becomes equal to or more than the threshold value Ns reaches the 1 st period T1 from the time when the rotation speed Nr becomes equal to or more than the threshold value Ns, the ratio r is decreased, and when the 2 nd elapsed time during which the rotation speed Nr continuously becomes less than the threshold value Ns reaches the 2 nd period T2 from the time when the rotation speed Nr becomes less than the threshold value Ns, the ratio r is increased. The threshold Ns is a value within a predetermined range necessary for achieving the object of the present invention. As shown in fig. 3B and 3C, the actual rotation speed Nr of the motor 1 may repeatedly increase and decrease at a short cycle due to signal noise or the like. Even if such a variation in the rotation speed Nr occurs, by performing the above-described processing using the 1 st period T1 and the 2 nd period T2, it is possible to prevent the ratio r from being frequently changed in accordance with such a variation in the rotation speed Nr. Therefore, voltage detection unit 22 can detect induced voltage Vi with stable detection accuracy.
< 1-5. variation
Next, a plurality of modifications of the embodiment will be explained. In the following description of the modifications, a configuration different from the above-described embodiment and other modifications will be described. The same components as those in the above-described embodiment and other modifications are denoted by the same reference numerals, and descriptions thereof are omitted.
< 1-5-1. variation 1 >)
In the above embodiment, the ratio r can be changed by switching in 1 step. In modification 1, the ratio ra of the voltage level Vd of the detection signal Sd output from the voltage detection unit 22 to the induced voltage Vi can be changed in multiple stages.
Fig. 4 is a schematic diagram showing a configuration example of the voltage detection unit 22 in modification 1. Since the U-phase voltage detection unit 22U, the V-phase voltage detection unit 22V, and the W-phase voltage detection unit 22W have the same configuration, fig. 4 illustrates the configuration of the W-phase voltage detection unit 22W.
As shown in fig. 4, the voltage detection unit 22 further includes a 4 th resistor R4. The 4 th resistor R4 is connected in parallel with the 2 nd resistor R2 and the 3 rd resistor R3. Preferably, the resistance value of the 4 th resistor R4 is greater than the resistance value of the 2 nd resistor R2. The ratio changing unit 221 includes a 1 st ratio changing unit 2211 and a 2 nd ratio changing unit 2212. The 1 st ratio changing part 2211 is connected in series to the 3 rd resistor R3. The 2 nd ratio changing part 2212 is connected in series to the 4 th resistor R4.
In the voltage divider circuit shown in fig. 4, the 1 st ratio changing section 2211 is connected in parallel to the 2 nd resistor R2 together with the 3 rd resistor R3. One end of the 1 st ratio changing portion 2211 is connected to the other end of the 3 rd resistor R3. The other end of the 1 st ratio changing portion 2211 is grounded. The 2 nd ratio changing part 2212 and the 4 th resistor R4 are connected in parallel to the 2 nd resistor R2. The 4 th resistor R4 is connected in series with the 2 nd ratio changing portion 2212. For example, one end of the 4 th resistor R4 is connected to the other end of the 1 st resistor R1. The other end of the 4 th resistor R4 is connected to one end of the 2 nd ratio changing portion 2212. The other end of the 2 nd ratio changing portion 2212 is grounded.
Further, although the 1 st ratio changing part 2211 and the 2 nd ratio changing part 2212 are field effect transistors in fig. 4, they may be other switching elements such as bipolar transistors and IGBTs. Further, the 1 st ratio changing portion 2211 and the 2 nd ratio changing portion 2212 are switched on and off in accordance with a switching signal Ss output from the detection control portion 253.
Next, an operation example of the motor control device 2 related to the voltage detection unit 22 in modification 1 will be described with reference to fig. 5 and 6. Fig. 5 is a flowchart for explaining a control example in the 1 st modification of the motor control device 2 related to the voltage detection unit 22. Fig. 6 is a graph showing a control example in modification 1 of the motor control device 2 related to the voltage detection unit 22. In the upper graph of fig. 6, a solid line Nr represents the rotation speed of the motor 1. In the lower graph of fig. 6, a solid line Vd indicates the voltage level of the detection signal Sd changed according to the flowchart of fig. 5. The broken line Vr1a indicates a voltage level (r1a × Vi) when the 1 st ratio r1a is multiplied by the induced voltage Vi. The broken line Vr2a indicates a voltage level (r2a × Vi) when the induced voltage Vi is multiplied by the 2 nd ratio r2a smaller than the 1 st ratio r1 a. The broken line Vr3a indicates a voltage level (r3a × Vi) when the induced voltage Vi is multiplied by the 3 rd ratio r3a smaller than the 2 nd ratio r2 a.
The flowchart of fig. 5 starts when the motor 1 is started, for example, and ends when the motor 1 is stopped. At the beginning of the flowchart of fig. 5, the 1 st ratio changing part 2211 and the 2 nd ratio changing part 2212 are disconnected.
First, the detection controller 253 determines whether or not the rotation speed Nr of the motor 1 is equal to or greater than the 1 st threshold Ns1 (step S201).
If it is not determined that the rotation speed Nr is equal to or greater than the 1 st threshold Ns1 (no in step S201), the detection controller 253 determines whether or not the 3 rd elapsed time has reached the 3 rd period T3a (step S202). In the 1 st modification, the 3 rd elapsed time is a period during which the rotation speed Nr is continuously less than the 1 st threshold Ns1 from the time td2 at which the rotation speed Nr becomes less than or equal to the 1 st threshold Ns 1.
If it is not determined that the 3 rd elapsed time has reached the 3 rd period T3a (no in step S202), the flowchart of fig. 5 returns to step S201.
When it is determined that the 3 rd elapsed time has reached the 3 rd period T3a (yes in step S202), the detection control unit 253 turns off the 1 st ratio changing unit 2211 and the 2 nd ratio changing unit 2212, respectively (step S203). Thus, the ratio ra of the voltage level Vd of the detection signal Sd output by the voltage detection unit 22 to the induced voltage Vi becomes the maximum 3 rd ratio r3 a. Then, the flowchart of fig. 5 returns to step S201.
On the other hand, when it is determined that the rotation speed Nr is equal to or greater than the 1 st threshold Ns1 (yes in step S201), the detection controller 253 determines whether or not the rotation speed Nr is equal to or greater than the 2 nd threshold Ns2 (step S204). In addition, the 2 nd threshold Ns2 is higher than the 1 st threshold Ns 1.
If it is not determined that the rotation speed Nr is equal to or greater than the 2 nd threshold Ns2 (no in step S204), the detection controller 253 determines whether or not the 2 nd elapsed time has reached the 2 nd period T2a (step S205). In the 1 st modification, the 2 nd elapsed time is a period during which the rotation speed Nr continues to be equal to or greater than the 1 st threshold Ns1 and less than the 2 nd threshold Ns2 from the time tu1 at which the rotation speed Nr becomes equal to or greater than the 1 st threshold Ns1 or the time td1 at which the rotation speed Nr becomes less than the 2 nd threshold Ns 2.
If it is not determined that the 2 nd elapsed time has reached the 2 nd period T2a (no in step S205), the flowchart of fig. 5 returns to step S201.
When determining that the 2 nd elapsed time has reached the 2 nd period T2a (yes in step S205), the detection control unit 253 turns on the 1 st ratio changing unit 2211 and turns off the 2 nd ratio changing unit 2212 (step S206). Thereby, the ratio ra becomes a 2 nd ratio r2a smaller than the 3 rd ratio r3a and larger than the 1 st ratio r1 a. Then, the flowchart of fig. 5 returns to step S201.
On the other hand, when it is determined that the rotation speed Nr is equal to or greater than the 2 nd threshold Ns2 (yes in step S204), the detection controller 253 determines whether or not the 1 st elapsed time has reached the 1 st period T1a (step S207). In the 1 st modification, the 1 st elapsed time is a period during which the rotation speed Nr is continuously equal to or greater than the 2 nd threshold Ns2 from the time tu2 at which the rotation speed Nr becomes equal to or greater than the 2 nd threshold Ns 2.
If it is not determined that the 1 st elapsed time has reached the 1 st period T1a (no in step S207), the flowchart of fig. 5 returns to step S201.
On the other hand, if it is determined that the 1 st elapsed time has reached the 1 st period T1a (yes in step S207), the detection control unit 253 turns on the 1 st ratio changing unit 2211 and the 2 nd ratio changing unit 2212 (step S208). Thereby, the ratio ra becomes the 1 st ratio r1a which is the smallest. Then, the flowchart of fig. 5 returns to step S201.
In the flowchart of fig. 5, at least any one of steps S202, S205, and S207 may be omitted. For example, when step S202 is omitted, the flowchart of fig. 5 proceeds to step S203 in the case where step S201 is no. That is, if the rotation speed Nr of the motor 1 is less than the 1 st threshold Ns1, the 1 st ratio changing part 2211 and the 2 nd ratio changing part 2212 are turned off. Thereby, the ratio ra is switched to the maximum 3 rd ratio r3 a. When step S205 is omitted, the flowchart of fig. 5 proceeds to step S206 if step S204 is no. That is, if the rotation speed Nr is the 1 st threshold Ns1 or more and less than the 2 nd threshold Ns2, the 1 st ratio change section 2211 is turned on and the 2 nd ratio change section 2212 is turned off. Thereby, the ratio ra is switched to the 2 nd ratio r2a which is larger than the 1 st ratio r1a and smaller than the 3 rd ratio r3 a. When step S207 is omitted, the flowchart of fig. 5 proceeds to step S208 when step S204 is yes. That is, if the rotation speed Nr is equal to or greater than the 2 nd threshold Ns2, the 1 st ratio changing part 2211 and the 2 nd ratio changing part 2212 are turned on. Thereby, the ratio ra is switched to the smallest 1 st ratio r1 a.
In the above description, the ratio ra is changed in 2 steps. However, the ratio ra is not limited to this example, and may be changed in 3 stages or more. Such a configuration can be realized by, for example, connecting a plurality of series-connected bodies of 3 or more resistors and ratio changing unit 221 in parallel with the 2 nd resistor R2.
According to the modification 1, the threshold Ns of the rotation speed Nr is plural and has different values. For example, in fig. 5, the threshold Ns includes a 1 st threshold Ns1 and a 2 nd threshold Ns2 higher than the 1 st threshold Ns 1. In this way, the ratio ra between the voltage level Vd of the detection signal Sd output from the voltage detection unit 22 and the induced voltage Vi can be switched in multiple stages. Therefore, the ratio ra can be appropriately changed according to the change characteristic of the induced voltage Vi according to the rotation speed Nr of the motor 1.
Note that the plurality of thresholds Ns such as the 1 st threshold Ns1 and the 2 nd threshold Ns2 can be set to Na < Ns < Nb with respect to the rotation speeds Na, Nb (> Na) of the motor 1 used in practice. The plurality of thresholds Ns are preferably set to values distant from the rotation speeds Na and Nb, and may be set to, for example, an intermediate value { (Na + Nb)/2} of the two or a value close to the intermediate value. In this way, since the plurality of thresholds Ns are values distant from the actually used rotation speeds Na and Nb, it is possible to suppress the ratio ra from being frequently changed in accordance with the variation in the rotation speed Nr of the motor 1.
< 1-5-2 > variation 2
In the above embodiment, the ratio r is switched regardless of the trend of the rotation speed Nr. In modification 2, when the rotation speed Nr is in an increasing trend and when the rotation speed Nr is in a decreasing trend, the ratio rb between the voltage level Vd of the detection signal Sd output from the voltage detection unit 22 and the induced voltage Vi is switched using different threshold values.
In modification 2, an example of the operation of the motor control device 2 related to the voltage detection unit 22 in modification 2 will be described with reference to fig. 7 and 8. Fig. 7 is a flowchart for explaining control in the 2 nd modification of the motor control device 2 related to the voltage detection unit 22. Fig. 8 is a graph showing a control example in the 2 nd modification of the motor control device 2 related to the voltage detection unit 22. In the upper graph of fig. 8, a solid line Nr represents the rotation speed of the motor 1. In the lower graph of fig. 8, a solid line Vd indicates the voltage level of the detection signal Sd changed according to the flowchart of fig. 7. The broken line Vr1b indicates a voltage level (r1b × Vi) when the 1 st ratio r1b is multiplied by the induced voltage Vi. The broken line Vr2b indicates a voltage level (r2b × Vi) when the induced voltage Vi is multiplied by the 2 nd ratio r2b larger than the 1 st ratio r1 b.
The flowchart of fig. 7 starts when the motor 1 is started, for example, and ends when the motor 1 is stopped. At the start of the flowchart of fig. 7, the ratio changing unit 221 is turned off.
First, the detection control unit 253 determines whether or not the rotation speed Nr of the motor 1 is increasing (step S301). The trend of the rotation speed Nr to increase or decrease can be detected by, for example, obtaining a moving average of the rotation speed Nr with time. In addition, within a predetermined time from the start of the motor 1, the rotation speed Nr can be determined to be in an increasing trend without detecting an increasing trend.
If it is determined that the rotation speed Nr is increasing (yes in step S301), the detection control unit 253 determines whether the rotation speed Nr is equal to or greater than the upper threshold NsH (step S302). If it is not determined that the rotation speed Nr is equal to or greater than the upper threshold NsH (no in step S302), the flowchart of fig. 7 returns to step S301.
If it is determined that the rotation speed Nr is equal to or greater than the upper threshold NsH (yes in step S302), detection controller 253 determines whether or not the 1 st elapsed time has reached the 1 st period T1b (step S303). In modification 2, the 1 st elapsed time is a period in which the rotation speed Nr is continuously equal to or greater than the upper threshold NsH from the time tu at which the rotation speed Nr becomes equal to or greater than the upper threshold NsH. If it is not determined that the 1 st elapsed time has reached the 1 st period T1b (no in step S303), the flowchart of fig. 7 returns to step S301.
When determining that the 1 st elapsed time has reached the 1 st period T1b (yes in step S303), the detection controller 253 turns on the ratio changer 221 (step S304). Thereby, the ratio rb becomes the smaller 1 st ratio r1 b. Then, the flowchart of fig. 7 returns to step S301.
On the other hand, if it is not determined that the rotation speed Nr is increasing (no in step S301), the detection controller 253 determines whether the rotation speed Nr is less than a lower threshold NsL which is lower than the upper threshold NsH (step S305). In addition, the lower threshold NsL is lower than the upper threshold NsH. If it is not determined that rotation speed Nr is less than lower threshold value NsL (no in step S305), the flowchart of fig. 7 returns to step S301.
If it is determined that the rotation speed Nr is smaller than the lower threshold NsL (yes in step S305), the detection controller 253 determines whether or not the 2 nd elapsed time has reached the 2 nd period T2b (step S306). In modification 2, the 2 nd elapsed time is a period in which the rotation speed Nr is continuously less than the lower threshold value NsL from the time td at which the rotation speed Nr becomes less than the lower threshold value NsL. If it is not determined that the 2 nd elapsed time has reached the 2 nd period T2b (no in step S306), the flowchart of fig. 7 returns to step S301.
When determining that the 2 nd elapsed time has reached the 2 nd period T2b (yes in step S306), the detection control unit 253 turns off the ratio changing unit 221 (step S307). Thereby, the ratio rb becomes a larger 2 nd ratio r2 b. Then, the flowchart of fig. 7 returns to step S301.
In the flowchart of fig. 7, at least one of steps S303 and S306 may be omitted. For example, when step S303 is omitted, the flowchart of fig. 7 proceeds to step S304 in the case where step S302 is yes. That is, if the rotation speed Nr of the motor 1 is equal to or higher than the upper threshold NsH, the ratio change unit 221 is turned on. Thereby, the ratio rb is switched to the smaller 1 st ratio r1 b. When step S306 is omitted, the flowchart of fig. 7 proceeds to step S307 when step S305 is yes. That is, if the rotation speed Nr is smaller than the lower threshold value NsL, the ratio changing unit 221 is turned off. Thereby, the ratio rb is switched to the 2 nd ratio r2b larger than the 1 st ratio r1 b.
In the 2 nd modification described above, the threshold value Ns includes the upper threshold value NsH and the lower threshold value NsL lower than the upper threshold value NsH. When the rotation speed Nr becomes the upper threshold NsH or more, the detection controller 253 further decreases the ratio rb. When the rotation speed Nr becomes smaller than the lower threshold NsL, the detection control portion 253 further increases the ratio rb. Namely, the following control is performed: when the rotation speed Nr becomes equal to or higher than the upper threshold NsH, the ratio r is decreased, and when the rotation speed Nr becomes lower than the lower threshold NsL, the ratio r is increased. The upper threshold NsH and the lower threshold NsL are each a numerical value within a predetermined range. Here, the specified range means a range of numerical values greater than Na and less than Nb. Further, the upper threshold NsH is greater than the lower threshold NsL. Thus, it is not easy to frequently change the ratio r according to the change in the rotation speed Nr. Therefore, voltage detection unit 22 can detect induced voltage Vi with stable detection accuracy.
The upper threshold NsH and the lower threshold NsL can be set to Na < NsL < NsH < Nb with respect to the rotation speeds Na, Nb (> Na) of the motor 1 used in practice. The upper threshold NsH and the lower threshold NsL are preferably values distant from the rotation speeds Na and Nb, and may be set to, for example, the value { (Na + Nb)/2} between them or a value close to them. In this way, since the upper threshold NsH and the lower threshold NsL are values far from the actually used rotation speeds Na and Nb, it is possible to suppress the ratio rb from being frequently changed in accordance with the variation in the rotation speed Nr.
Further, the detection control unit 253 performs the following control: when the 1 st elapsed time during which the rotation speed Nr continuously becomes equal to or greater than the upper threshold NsH from the time tu at which the rotation speed Nr becomes equal to or greater than the upper threshold NsH reaches the 1 st period T1b, the ratio rb is further decreased. The detection controller 253 performs the following control: when the 2 nd elapsed time, at which the rotation speed Nr is continuously less than the lower threshold NsL, reaches the 2 nd period T2b from the time td at which the rotation speed Nr becomes less than the lower threshold NsL, the ratio rb is further increased. In this way, it is possible to more reliably prevent the ratio rb from being frequently changed in accordance with the variation in the rotation speed Nr. Therefore, voltage detection unit 22 can detect induced voltage Vi with more stable detection accuracy.
< 1-5-3 > variation 3
In the above-described embodiment, modification 1, and modification 2, the change ratios r, ra, and rb are switched in stages. In contrast, in modification 3, the ratio rc of the voltage level Vd of the detection signal Sd output from the voltage detection unit 22 to the induced voltage Vi can be continuously changed.
Fig. 9 is a schematic diagram showing a configuration example of the voltage detection unit 22 in modification 3. Since the U-phase voltage detection unit 22U, the V-phase voltage detection unit 22V, and the W-phase voltage detection unit 22W have the same configuration, the configuration of the W-phase voltage detection unit 22W is illustrated in fig. 9.
As shown in fig. 9, the motor control device 2 further has a D/a converter 26. The D/a converter 26 is disposed between the voltage detection unit 22 and the detection control unit 253 of the control unit 25. The D/a converter 26 converts the digital switching signal Ss into an analog switching signal Sa, and outputs the analog switching signal Sa to the voltage detection unit 22.
The ratio changing unit 221a of the voltage detecting unit 22 is a variable resistor such as a potentiometer. The ratio changing unit 221a receives the analog switching signal Sa and continuously changes the resistance value in accordance with the voltage level of the analog switching signal Sa. For example, when the rotation speed Nr becomes high, the resistance value of the ratio changing portion 221a increases and the ratio rc becomes smaller according to the increase amount of the voltage level of the switching signal Ss. When the rotation speed Nr becomes low, the resistance value of the ratio changing unit 221a decreases by the amount of decrease in the voltage level of the switching signal Ss, and the ratio rc becomes larger.
According to the modification 3, since the ratio rc can be continuously changed, the ratio rc can be more appropriately changed according to the change characteristic of the induced voltage Vi according to the rotation speed Nr of the motor 1.
< 2. other >)
The embodiments of the present invention have been described above. The scope of the present invention is not limited to the above-described embodiments. The present invention can be implemented by variously changing the above-described embodiments without departing from the gist of the present invention. The matters described in the above embodiments can be arbitrarily combined as appropriate within a range not inconsistent with each other.
The present invention is useful for, for example, a device that controls the rotational speed of a motor based on the detection result of an induced voltage generated in a stator coil.
Claims (6)
1. A motor control device for controlling a motor, characterized in that,
the motor control device includes:
a voltage detection unit that detects an induced voltage generated in a stator coil of the motor and outputs a detection signal indicating a value of the induced voltage;
a rotation speed detecting unit that detects a rotation speed of the motor based on the detection signal; and
a detection control unit for controlling the voltage detection unit,
the voltage detection unit has a ratio change unit capable of changing a ratio of a voltage level of the detection signal to the induced voltage,
the detection control unit controls the ratio change unit according to the rotation speed.
2. The motor control apparatus according to claim 1,
the voltage detection part also comprises a 1 st resistor, a 2 nd resistor and a 3 rd resistor,
the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio changing part form a voltage dividing circuit that detects the induced voltage,
one end of the 1 st resistor is connected to the stator coil,
the 2 nd resistor is connected to the other end of the 1 st resistor and is connected in parallel to the ratio changing unit and the 3 rd resistor,
the 3 rd resistor is connected to the other end of the 1 st resistor and is connected in series to the ratio changing unit,
the ratio changing unit switches between a conductive state and a non-conductive state of the 3 rd resistor according to a switching signal output from the detection control unit.
3. The motor control apparatus according to claim 1,
the voltage detection part also comprises a 1 st resistor, a 2 nd resistor and a 3 rd resistor,
the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio changing part form a voltage dividing circuit that detects the induced voltage,
one end of the 1 st resistor is connected to the stator coil,
the 2 nd resistor is connected to the other end of the 1 st resistor and is connected in parallel to the ratio changing unit and the 3 rd resistor,
the 3 rd resistor is connected to the other end of the 1 st resistor and is connected in series to the ratio changing unit,
the ratio changing unit switches between a conductive state and a non-conductive state of the 3 rd resistor according to a switching signal output from the detection control unit,
the resistance value of the 3 rd resistor is larger than that of the 2 nd resistor.
4. The motor control apparatus according to claim 1,
the voltage detection part also comprises a 1 st resistor, a 2 nd resistor and a 3 rd resistor,
the 1 st resistor, the 2 nd resistor, the 3 rd resistor, and the ratio changing part form a voltage dividing circuit that detects the induced voltage,
one end of the 1 st resistor is connected to the stator coil,
the 2 nd resistor is connected to the other end of the 1 st resistor and is connected in parallel to the ratio changing unit and the 3 rd resistor,
the 3 rd resistor is connected to the other end of the 1 st resistor and is connected in series to the ratio changing unit,
the ratio changing unit switches between a conductive state and a non-conductive state of the 3 rd resistor according to a switching signal output from the detection control unit,
the ratio changing unit includes a field effect transistor.
5. The motor control apparatus according to claim 1,
the motor control device further includes a signal conversion unit that converts the detection signal into a pulse signal and outputs the pulse signal to the rotational speed detection unit.
6. A motor unit is characterized in that,
the motor unit includes:
the motor control device according to any one of claims 1 to 5; and
a motor controlled by the motor control device,
the motor has:
a rotor rotatable about a central axis; and
a stator that drives the rotor,
one end of the stator coil of the stator is connected to the motor control device.
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| JP2020-022497 | 2020-02-13 | ||
| JP2020022497A JP2021129395A (en) | 2020-02-13 | 2020-02-13 | Motor controller and motor unit |
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| CN (1) | CN215912055U (en) |
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