JP2004064860A - Motor controlling equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controlling equipment capable of stably sensorless driving a synchronous motor with a simple and low-cost configuration. <P>SOLUTION: A motor controlling equipment 1 comprises a voltage amplitude setting part 44 which sets the amplitude of a voltage applied to a synchronous reluctance motor 2 to a prescribed value preset according to a command rotational speed and command torque, sense MOSFTs 31ul, 31vl, and 31wl for detecting a motor current, a sine wave basic function integrator 48 which detects a phase difference between a detected motor current and the applied voltage, a voltage phase basic value setting part 43 and feedback part 49 which set a phase of the applied voltage so that the phase difference between the motor current and the applied voltage agrees with a target phase difference set according to the command rotational speed and the command torque, and an applied voltage duty generating part 46 which generates an applied voltage duty supplied to an inverter circuit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor control device, and more particularly, to a motor control device for driving and controlling a synchronous motor having salient polarities having a plurality of phases of motor coils without using a position sensor.
[0002]
[Prior art]
Conventionally, as a so-called sensorless drive method for driving and controlling a synchronous motor having a multi-phase coil such as a synchronous reluctance motor without using a rotor position sensor, for example, an estimated current value calculated from an applied voltage and a motor model is used. There has been proposed a technique of estimating a rotor position based on a difference from an actually measured current value measured by a current sensor.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional technology, a complicated calculation process for sequentially calculating the estimated current value from the motor model is required in the drive control process, and thus a microcomputer capable of high-speed processing needs to be used. Further, since the rotor position is estimated using the measured current value measured by the current sensor, it is necessary to obtain an accurate measured current value, and a highly accurate current sensor is required. For this reason, there is a problem that not only the drive control processing in the motor control device becomes complicated, but also the manufacturing cost of the control device increases.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide a motor control device that can stably drive a synchronous motor with a simple and inexpensive configuration without a sensor.
[0005]
[Means for Solving the Problems]
In order to achieve this object, a motor control device according to claim 1, wherein a motor control for driving a synchronous motor having a plurality of phases of motor coils and having a salient polarity by an inverter circuit including a plurality of switching elements. In the apparatus, voltage amplitude setting means for setting the amplitude of an applied voltage applied to the synchronous motor to a predetermined value predetermined according to a command rotation speed and a command torque, and a motor of at least one of the plurality of phases Current detection means for detecting a current; phase difference detection means for detecting a phase difference between the motor current detected by the current detection means and the applied voltage; and a phase difference between the motor current and the applied voltage being the command. Applied voltage phase setting means for setting the phase of the applied voltage so as to match a target phase difference set in accordance with a rotation speed and the command torque And an applied voltage duty creating means for creating an applied voltage duty to be supplied to the inverter circuit based on the voltage amplitude set by the voltage amplitude setting means and the voltage phase set by the applied voltage phase setting means. It is characterized by having.
[0006]
Therefore, the voltage amplitude setting means sets the amplitude of the applied voltage to be applied to the synchronous motor to a predetermined value determined in advance according to the command rotation speed and the command torque, and the current detection means sets at least one of the plurality of phases. The motor current of one phase is detected, the phase difference detecting means detects a phase difference between the motor current detected by the current detecting means and the applied voltage, and the applied voltage phase setting means detects the motor current and the applied voltage. The phase of the applied voltage is set so that a phase difference from the applied voltage matches a target phase difference set according to the command rotation speed and the command torque, and the applied voltage duty creating means includes the voltage amplitude setting means. And generating an applied voltage duty to be supplied to the inverter circuit based on the voltage amplitude set by the control unit and the voltage phase set by the applied voltage phase setting means. That.
[0007]
Therefore, if the phase difference between the motor current and the applied voltage does not match the target phase difference, the applied voltage phase setting means applies the voltage so that the phase difference between the motor current and the applied voltage matches the target phase difference. Since the phase of the voltage is set, the drive of the synchronous motor can be stably controlled. Further, the voltage amplitude setting means sets the amplitude of the applied voltage applied to the synchronous motor to a predetermined value which is predetermined according to the command rotation speed and the command torque. , The voltage amplitude is constant. At this time, the characteristic of the synchronous motor having saliency causes the torque to autonomously occur and the rotor position autonomously returns to the target control position, so that the synchronous motor can be more stably driven and controlled.
[0008]
Further, in the motor control device according to claim 2, the phase difference detection unit samples the motor current detected by the current detection unit at a predetermined cycle, and from a sampling time immediately after the polarity of the sampled value is inverted. Next, the period up to the sampling point immediately after the polarity inversion, or from the sampling point in which the same polarity has been repeated two or more predetermined times after the polarity of the sampled value has been inverted, the same polarity has become two or more after the next polarity inversion. In a period up to a predetermined number of consecutive sampling times, an integral value of the sine wave basic function is calculated, and a phase difference between the motor current and the applied voltage is detected based on the integral value.
[0009]
Therefore, since only the polarity information of the motor current is used, there is no need to consider the gain error of the current sensor, and the configuration can be made using an inexpensive current sensor. Furthermore, since the integrated value of the sine wave basic function is used, even if an error occurs during the integration period due to noise in the motor current, the influence on the integrated value is small, and the phase difference between the motor current and the applied voltage is always accurate. Can be detected.
[0010]
The motor control device according to claim 3 is characterized in that the current detection means is configured to detect a current in an upper stage or a lower stage of at least one arm of the inverter circuit.
[0011]
Therefore, by using a current sensor such as a sense MOSFET for detecting the arm current, it is possible to reduce the size and cost of the motor control device.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a motor control device embodying the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a block diagram illustrating an overall configuration of a motor control device 1 according to the present embodiment.
[0014]
As shown in FIG. 1, a motor control device 1 is a synchronous reluctance motor (SynRM) (hereinafter, also simply referred to as a motor) as a synchronous motor including a stator including coils of a plurality of phases (three phases) and an iron core rotor. The drive circuit 2 includes an inverter circuit 3 and a microcomputer (hereinafter referred to as a microcomputer) 4.
[0015]
As shown in the circuit diagram of FIG. 2, the inverter circuit 3 is connected to a DC power supply 30 and supplies a power MOSFET 31 uh (upper arm), a sense MOSFET 31 ul (lower arm), and a V-phase A power MOSFET 31vh (upper arm), a sense MOSFET 31vl (lower arm), a power MOSFET 31wh (upper arm), and a sense MOSFET 31wl (lower arm) that supply power to the W-phase are connected to each other. Sense MOSFETs 31ul, 31vl, 31wl are connected to the lower arm of each phase, and are configured to detect an arm current signal flowing when the gate signal of the lower arm of each phase is ON. The relationship between the motor current and the arm current is as shown in the graph of FIG. 3, and the current value of the motor current at predetermined time intervals is the arm current value. The sense MOSFET 31ul (31vl, 31wl) shunts the arm current and detects the current. Hereinafter, in this specification, the arm current is treated as the motor current. Note that the sense MOSFETs 31ul, 31vl, 31wl constitute the current detecting means of the present invention.
[0016]
The microcomputer 4 includes a CPU, a ROM, and a RAM (not shown). The CPU reads and executes a program stored in the ROM, and thereby a torque setting unit 41, a rotation speed setting unit 42, and a voltage phase basic value setting. A unit 43, a voltage amplitude setting unit 44, a sine wave basic function creation unit 45, an applied voltage duty creation unit 46, a target sine wave basic function integral value setting unit 47, and a sine wave basic function integrator 48 are realized. Is what you do. Note that the voltage amplitude setting unit 44 performs the voltage amplitude setting unit of the present invention, the sine wave basic function generation unit 45 performs the sine wave basic function generation unit, the applied voltage duty generation unit 46 performs the applied voltage duty generation unit, and The basic function integrator 48 constitutes a phase difference detecting means. .
[0017]
The torque setting unit 41 sets a command torque based on a command or the like from a host device in which the motor control device 1 is incorporated.
[0018]
The rotation speed setting unit 42 sets a command rotation speed based on a command or the like from a host device in which the motor control device 1 is incorporated.
[0019]
The voltage phase basic value setting unit 43 sets the voltage phase basic value based on the command torque set by the torque setting unit 41 and the command rotation speed set by the rotation speed setting unit 42. More specifically, a data table including a data sequence of a voltage phase basic value with respect to a command torque and a command rotation speed is stored in the ROM, and a voltage phase basic value is obtained from the data table based on the command torque and the command rotation speed. The settings are read out.
[0020]
The voltage amplitude setting unit 44 sets the voltage amplitude based on the command torque set by the torque setting unit 41 and the command rotation speed set by the rotation speed setting unit 42. More specifically, a data table including a data string of a voltage amplitude value with respect to a command torque and a command rotation speed is stored in the ROM, and the voltage amplitude value is read from the data table based on the command torque and the command rotation speed. The settings are made.
[0021]
The sine wave basic function creation unit 45 is based on the frequency determined by the command rotation speed set in the rotation speed setting unit 42, and the phase difference between the applied voltage and the motor voltage set in the voltage phase basic value setting unit 43. Then, a sine wave basic function of the applied voltage is created based on the voltage phase basic value corrected in this way.
[0022]
The applied voltage duty creating section 46 uses the voltage amplitude set by the voltage amplitude setting section 44 and the sine wave basic function created by the sine wave basic function creating section 45 to apply an applied voltage duty (PWM signal) for driving the motor 2. ) Is prepared and supplied to the inverter circuit 3.
[0023]
The sine wave basic function integrator 48 integrates the sine wave basic function created in the sine wave basic function creation section 45 during an integration period determined based on the current signal output from the inverter circuit 3, and Calculate the function integral.
[0024]
Here, the processing contents of the sine wave basic function integrator 48 will be described in detail with reference to FIG.
[0025]
In FIG. 4, a graph of the motor current value (arm current value) measured by the sense MOSFET 31ul (31vl, 31wl) and a graph of the sine wave basic function of the applied voltage are vertically arranged. The motor current value is sampled at a predetermined cycle, and each sampled value is indicated by a plurality of points plotted on a graph. Here, as shown in FIG. 4, the polarity of the motor current value is negative at the sampling time t0, positive at t1 to t9, and negative at t10 to t18. That is, the polarity is inverted from negative to positive at t1, and the polarity is inverted again from positive to negative at t10.
[0026]
Then, the integration of the sine wave basic function is performed in a period from a sampling point in time t1 immediately after the polarity of the current sampling value is inverted and becomes positive to a sampling point in time t10 immediately after the polarity is inverted and becomes negative. Do. Here, the integration period (t1 to t10) is determined by the phase difference between the sine wave basic function and the motor current value, and the integration value of the sine wave basic function is determined by the integration period. Is also true.
[0027]
For example, when the phase difference is 0 °, the integral value is indicated by the hatched portion in FIG. When 0 ° <phase difference <90 °, the integrated value is indicated by the hatched portion in FIG. 5B and is an intermediate value between the maximum value and 0. When the phase difference is 90 °, the integral value becomes 0 as shown by the hatched portion in FIG. Further, when the phase difference is greater than 90 °, the integral value becomes a negative value.
[0028]
Therefore, by calculating the integral value of the sine wave basic function, the phase difference between the motor current value and the sine wave basic function (that is, the applied voltage) can be recognized.
[0029]
Based on the command torque set by the torque setting unit 41 and the command rotation speed set by the rotation speed setting unit 42, the target sine wave basic function integral value setting unit 47 calculates the sine wave basic function corresponding to the target phase difference. Set the target sine wave basic function integral value that is the integral value. More specifically, a data table including a data string of a target sine wave basic function integral value with respect to the command torque and the command rotation speed is stored in the ROM, and the target sine wave is obtained from the data table based on the command torque and the command rotation speed. The setting is performed by reading the integral value of the wave basic function.
[0030]
Then, a deviation between the sine wave basic function integrated value calculated by the sine wave basic function integrator 48 and the target sine wave basic function integrated value set by the target sine wave basic function integrated value setting unit 47 is obtained. A value obtained by multiplying the deviation by the gain is fed back to the output side of the basic voltage phase value setting unit 43 (the feedback unit is indicated by reference numeral 49 in FIG. 1). The gain of the feedback system is calculated in advance and stored in the ROM. Further, the voltage phase basic value setting section 43 and the feedback section 49 constitute the applied voltage phase setting means of the present invention. That is, the voltage phase basic value set by the voltage phase basic value setting unit 43 is a phase difference information between the motor current and the applied voltage represented by a deviation between the target sine wave basic function integral value and the sine wave basic function integral value. , And is input to the sine wave basic function creation unit 45. Accordingly, since the phase difference between the motor current and the applied voltage is fed back to the applied voltage phase, the drive of the motor 2 is stably controlled.
[0031]
As described above, since only the polarity information of the motor current is used, there is no need to consider the gain error of the current sensor, and an inexpensive sense MOSFET can be used as the current sensor. Furthermore, since the integrated value of the sine wave basic function is used, even if an error occurs during the integration period due to noise in the motor current, the influence on the integrated value is small, and the phase difference between the motor current and the applied voltage is always accurate. Can be detected.
[0032]
Further, the voltage amplitude setting unit 44 sets the applied voltage to a predetermined value according to the command torque and the command rotation speed, and when the command torque and the command rotation speed are constant, the voltage amplitude is constant, so that the calculation is performed. If the integrated sine wave basic function integrated value does not match the target sine wave basic function integrated value (that is, if the phase difference between the applied voltage and the motor current does not match the target phase difference), the synchronous reluctance motor Due to the characteristics of (SynRM), torque autonomously occurs and acts to approach a normal phase difference. Therefore, the drive of the motor 2 is more stably controlled in combination with the above-described operation of the feedback control of the applied voltage phase.
[0033]
Here, the autonomous torque generation operation will be described with reference to FIGS. 6, 7, and 8. FIG. FIG. 6 shows a phase difference (a phase difference between an applied voltage and a motor current) when a synchronous reluctance motor (hereinafter abbreviated as SynRM) is controlled at a target control phase, and a difference between estimated coordinates from actual coordinates. 6 is a graph showing the relationship of. FIG. 7 shows a case where the constant voltage amplitude control is applied to the SynRM (target phase control in which the control phase is the voltage phase and the current phase is 45 ° when the voltage phase and the voltage amplitude are kept constant on the estimated coordinates is 110 °). Phase) and current amplitude constant control (current phase on current coordinates and current amplitude on estimated coordinates by providing a current minor loop, control phase is current phase, and current phase 45 ° is target control phase) 6 is a graph showing a relationship between a motor torque and a deviation of estimated coordinates from actual coordinates when is applied. FIG. 8 shows the relationship between the motor torque and the deviation of the estimated coordinates from the actual coordinates when the constant voltage amplitude control is applied to the synchronous motor having salient poles (SynRM) and the permanent magnet type synchronous motor (SPM). It is a graph shown.
[0034]
As is clear from the graph of FIG. 6, in the SynRM, the phase difference decreases when the estimated coordinate shift is around −45 ° to 15 ° (region A), and the phase difference starts increasing when the deviation is around 15 ° or more (region A). B). For this reason, there are two displacements of the estimated coordinates at the same phase difference, and it is not possible to uniquely estimate the displacement of the estimated coordinates from the phase difference. , It cannot be determined whether it is shifted to the delay side. However, when the estimated coordinates coincide with the actual coordinates (the estimated coordinate shift is 0), the area is within the area A. Therefore, when the estimated coordinate shift enters the area B, the area is automatically returned to the area A. Such control may be performed.
[0035]
In the present embodiment, the control phase is automatically returned to the region A by applying the constant voltage amplitude control to the SynRM. Hereinafter, the details will be described with reference to FIG. First, a problem of a method of applying the constant current amplitude control to SynRM, which is a conventional technique, will be described. When an error occurs between the actual coordinates and the estimated coordinates due to a torque disturbance or the like and the estimated coordinates deviate from the actual coordinates to the leading side (the actual rotor is delayed) (FIG. 9), the torque decreases and the rotation speed decreases. As a result, the actual rotor is further delayed, and the deviation of the estimated coordinates is further shifted toward the advanced side (the estimated coordinates are further advanced than the actual coordinates) (FIG. 10). Accordingly, when the estimated coordinates are shifted from the actual coordinates to the leading side and enter the area B, the shift of the estimated coordinates cannot be automatically returned to the area A, and the motor cannot be driven stably. On the other hand, in the method of applying the constant voltage amplitude control to the SynRM according to the present embodiment, an error occurs between the actual coordinates and the estimated coordinates, and the estimated coordinates shift from the actual coordinates to the leading side (the actual rotor is delayed). In this case (FIG. 11), the torque increases autonomously and the rotation speed rises, so that the actual rotor is advanced, and the estimated coordinate shifts closer to the actual coordinate with a delay in the estimated coordinate shift (FIG. 12). When the estimated coordinates deviate from the actual coordinates to the lag side (the actual rotor advances) (FIG. 13), the torque decreases autonomously and the rotational speed decreases, and the actual rotor is delayed and the estimated coordinates are reduced. And the estimated coordinates and the actual coordinates approach (FIG. 12). Therefore, even when the estimated coordinates deviate from the real coordinates to the leading side and enter the area B, the deviation of the estimated coordinates returns to the area A by the action of the torque generated autonomously, so that the SynRM can be stably controlled. It is.
[0036]
Further, FIG. 8 shows that the present invention has a stronger action of the autonomously generated torque and can more stably drive the motor than the conventional method of applying the constant voltage amplitude control to the permanent magnet synchronous motor (SPM). It will be described with reference to FIG. In the method of applying the constant voltage amplitude control to the permanent magnet synchronous motor (SPM) (the control phase is a voltage phase, and the voltage phase at which the current phase is 0 ° is 25 °, the target control phase), the estimated coordinates are the real coordinates. , The increase of the autonomously generated torque is very small as compared to SynRM. In addition, when the estimated coordinates are delayed from the actual coordinates, the torque that decreases autonomously is much smaller than that of SynRM. Therefore, the torque for autonomously stabilizing the motor is very small as compared with the method of applying the constant voltage amplitude control to the SynRM of the present embodiment. On the other hand, in the method of applying the constant voltage amplitude control to the SynRM according to the present embodiment, the torque that increases and decreases autonomously when the estimated coordinates advance from the actual coordinates or lags from the actual coordinates has a permanent magnet type synchronous motor ( SPM). As a result, the torque for autonomously stabilizing the motor is significantly increased as compared with the related art, and the motor can be driven more stably.
[0037]
The present invention is not limited to the above-described embodiments, and various changes can be made without departing from the gist of the present invention.
[0038]
For example, in the above-described embodiment, the phase difference detection unit samples the motor current detected by the sense MOSFET 31ul or the like at a predetermined cycle, and starts sampling immediately after the polarity of the sampling value is inverted and then immediately after the polarity is inverted. In the period up to the sampling point, the integral value of the sine wave basic function determined by the command speed and the applied voltage phase is calculated, and the phase difference between the motor current and the applied voltage is detected based on the integrated value. However, it is not limited to this. For example, the integration period may be defined as a period from a sampling time point at which the same polarity has been repeated two or more predetermined times after the polarity of the sampled value has been inverted to a sampling time point at which the same polarity has been repeated two or more times after the polarity has been inverted. Good. FIG. 14 shows that, after the polarity of the sampled value is inverted to change from negative to positive, the second sampling time t2 at which the polarity is continuously positive is set as the start of the period, and then the polarity is inverted and the polarity is changed from positive to negative. After that, an example is shown in which the second sampling point in time t11 at which the polarity has been continuously changed to negative is set as the end of the period. According to this modification, the time when the same polarity continues a predetermined number of times after the reversal of the polarity of the motor current is set to the start or end of the period. Therefore, even when the current polarity changes little by little due to the chattering of the motor current, the period of the period is changed. Erroneous detection at the start / end points can be more reliably prevented.
[0039]
Further, in the above-described embodiment, an example has been described in which the present invention is applied to a control device for a synchronous reluctance motor. However, the present invention may be applied to a control device for another type of synchronous motor having saliency. For example, the present invention may be applied to a control device of an internal magnet type permanent magnet synchronous motor (IPM motor) having a permanent magnet housed in a rotor core.
[0040]
Further, in the above embodiment, the configuration is such that the arm current signal of the lower stage of each phase is detected. However, the configuration may be such that the arm current signal of the upper stage of the arm is detected.
[0041]
【The invention's effect】
As described above, according to the motor control device of the present invention, when the phase difference between the motor current and the applied voltage does not match the target phase difference, the applied voltage phase setting unit sets the motor current and the applied voltage Since the phase of the applied voltage is controlled so that the phase difference of the synchronous motor coincides with the target phase difference, the synchronous motor can be stably driven. Further, the voltage amplitude setting means sets the amplitude of the applied voltage applied to the synchronous motor to a predetermined value which is predetermined according to the command rotation speed and the command torque. , The voltage amplitude is constant. At this time, the characteristics of the synchronous motor having saliency cause the torque to autonomously occur and the rotor position autonomously returns to the target control position, so that the synchronous motor can be more stably driven and controlled. To play. Furthermore, since there is no need for complicated calculation processing and high-precision current detection, there is an effect that the motor control device can be configured to be small and inexpensive using an inexpensive microcomputer or current sensor. Also play.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an overall configuration of a motor control device according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of an inverter circuit.
FIG. 3 is a graph showing a relationship between a motor current and an arm current.
FIG. 4 is an explanatory diagram showing an example of calculation of an integral value of a motor current waveform and a sine wave basic function.
FIG. 5 is an explanatory diagram showing a relationship between a phase difference between a motor current and an applied voltage and a sine wave basic function integrated value.
FIG. 6 is a graph showing a relationship between a phase difference between an applied voltage and a motor current and a shift of estimated coordinates from actual coordinates when control is performed at a target control phase in SynRM.
FIG. 7 is a graph showing a relationship between a motor torque and a deviation of estimated coordinates from actual coordinates when the constant voltage amplitude control is applied and when the current amplitude constant control is applied in SynRM.
FIG. 8 is a graph showing the relationship between motor torque and deviation of estimated coordinates from actual coordinates when voltage constant control is applied to a motor having salient poles (SynRM) and a permanent magnet synchronous motor (SPM). It is.
FIG. 9 is a vector diagram in a case where the estimated coordinates are shifted from the actual coordinates to the leading side in the conventional method of applying the constant current amplitude control to the SynRM.
FIG. 10 is a vector diagram in a case where the estimated coordinates further deviate from the actual coordinates toward the leading side due to a decrease in torque in the conventional method.
FIG. 11 is a vector diagram in a case where the estimated coordinates are shifted from the actual coordinates to the leading side in the present embodiment in which the constant voltage amplitude control is applied to the SynRM.
FIG. 12 is a vector diagram in a case where the advance of the actual rotor occurs due to the torque autonomously increasing in the present embodiment, and the estimated coordinates and the actual coordinates approach.
FIG. 13 is a vector diagram in a case where the estimated coordinates are shifted from the actual coordinates to the delay side in the present embodiment.
FIG. 14 is an explanatory diagram illustrating an example of calculation of an integral value of a motor current waveform and a sine wave basic function in a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Motor control device, 2 ... Synchronous reluctance motor (SynRM) (synchronous motor), 3 ... Inverter circuit, 4 ... Microcomputer, 31ul, 31vl, 31wl ... Sense MOSFET (current detection means), 43 ... Basic voltage phase value Setting unit, 44: voltage amplitude setting unit (voltage amplitude setting unit), 45: sine wave basic function creation unit, 45: applied voltage duty creation unit (applied voltage duty creation unit), 48: sine wave basic function integrator (unit) Phase difference detecting means), 49 feedback section, 43, 49 (applied voltage phase setting means).

Claims (3)

A motor control device that drives and controls a synchronous motor having saliency with multiple phases of motor coils by an inverter circuit configured by a plurality of switching elements.
Voltage amplitude setting means for setting the amplitude of the applied voltage to be applied to the synchronous motor to a predetermined value that is predetermined according to a command rotation speed and a command torque;
Current detection means for detecting a motor current of at least one of the plurality of phases,
Phase difference detecting means for detecting a phase difference between the motor current and the applied voltage detected by the current detecting means,
Applied voltage phase setting means for setting the phase of the applied voltage so that the phase difference between the motor current and the applied voltage matches a target phase difference set according to the command rotation speed and the command torque,
Applied voltage duty creating means for creating an applied voltage duty to be supplied to the inverter circuit based on the voltage amplitude set by the voltage amplitude setting means and the voltage phase set by the applied voltage phase setting means,
A motor control device comprising: The phase difference detection unit samples the motor current detected by the current detection unit at a predetermined cycle, and a period from a sampling point immediately after the polarity of the sampled value is inverted to a sampling point immediately after the polarity is inverted next. Or a sine wave in a period from a sampling point in time when the same polarity is repeated two or more predetermined times after the polarity of the sampled value is inverted to a sampling point in time when the polarity is inverted two or more predetermined times after the polarity is inverted. The motor control device according to claim 1, wherein an integrated value of a basic function is calculated, and a phase difference between the motor current and the applied voltage is detected based on the integrated value. The motor control device according to claim 1, wherein the current detection unit is configured to detect a current in an upper stage or a lower stage of at least one arm of the inverter circuit.

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