JP7585151B2 - Motor drive control device and method thereof, and motor drive control system - Google Patents

Description

The present invention relates to an electric motor drive control device and an electric motor drive control method for controlling the drive of an electric motor. The present invention also relates to an electric motor drive control system equipped with the electric motor drive control device.

Electric motors that convert electrical energy into mechanical energy are used for a variety of purposes, and generally include a rotor that has an axis and rotates around the axis, and a stator that is stationary relative to the rotor and magnetically interacts with the rotor, and the rotor is rotated by a rotating magnetic field. When such motors rotate, the positional relationship between the stator magnets and the rotor magnets changes, which can cause torque pulsation. To reduce this pulsating torque (torque pulsation), control devices are proposed in Patent Documents 1 and 2, for example.

The motor control device disclosed in this patent document 1 includes a basic voltage command calculation unit that calculates a basic value of a voltage command, a current detection unit that detects the current flowing through the windings of the motor, a magnetic flux estimation unit that estimates the interlinkage magnetic flux linking the windings based on the applied voltage applied to the windings and the detected value of the current, a torque estimation unit that estimates the output torque of the motor based on the detected value of the current and the estimated value of the interlinkage magnetic flux, a pulsation extraction unit that extracts a pulsation component from the estimated value of the output torque, a pulsation control unit that calculates a voltage command correction value based on the extracted value of the pulsation component, a superposition unit that superimposes the voltage command correction value on the basic value of the voltage command and calculates the superimposed voltage command, and a voltage application unit that applies a voltage to the windings via an inverter based on the superimposed voltage command. This voltage application unit includes a coordinate conversion unit that performs fixed coordinate conversion and two-phase to three-phase conversion on the superimposed dq axis voltage commands based on the magnetic pole position to calculate three-phase voltage commands, and a PWM control unit that compares each of the three-phase voltage commands with the triangular carrier wave to output a control signal corresponding to the rectangular pulse wave of each of the three phases.

The motor control device disclosed in Patent Document 2 is connected to a power converter that converts DC power to AC power, and controls the operation of an AC motor that is driven using the AC power. The motor control device includes a current command generation unit that generates a current command, a current control unit that generates a voltage command based on the current command, a gate signal generation unit that generates a gate signal for controlling the operation of the power converter based on the voltage command, and a current command correction unit that corrects the current command by superimposing a pulsation on the current command, and the current command correction unit changes the amplitude and phase of the pulsation based on the rotation speed of the AC motor.

JP 2020-178439 A JP 2020-188555 A

However, in the above-mentioned Patent Document 1, the superimposed voltage command for suppressing pulsation is input directly to the PWM control unit without going through feedback control. Therefore, if the gain setting in the pulsation suppression unit is not appropriate, there is a risk that the control system will become unstable.

On the other hand, in the above-mentioned Patent Document 2, if the command current value output by the current command correction unit contains a frequency that exceeds the frequency response of the current control unit, current control that follows the command value cannot be performed. In other words, it is difficult for the motor control device disclosed in the above-mentioned Patent Document 2 to suppress high-frequency pulsation that exceeds the frequency response of the current control unit.

The present invention was made in consideration of the above circumstances, and its purpose is to provide an electric motor drive control device, an electric motor drive control method, and an electric motor drive control system equipped with the electric motor drive control device, which can more appropriately suppress pulsating torque.

After extensive investigation, the inventors have found that the above object can be achieved by the present invention described below. That is, an electric motor drive control device according to one aspect of the present invention is a device for controlling an electric motor, and includes a pulsating torque estimation unit that estimates the pulsating torque that will occur at the next control timing by using a pulsating model that represents a pulsating torque whose magnitude increases and decreases over time, a compensation value generation unit that generates a compensation value for canceling the pulsating torque estimated by the pulsating torque estimation unit, and a drive control unit that controls and drives the electric motor with a control command value based on the compensation value generated by the compensation value generation unit, and the pulsating torque includes at least one of a first pulsating torque caused by a spatial high-frequency component of the magnetomotive force distribution in the circumferential direction of the electric motor, and a second pulsating torque that is a cogging torque.

Such an electric motor drive control device estimates the pulsating torque that will occur at the next control timing and generates a compensation value to cancel out this estimated pulsating torque, so that the pulsating torque, including at least one of the first and second pulsating torques that occur in the electric motor itself, can be more appropriately suppressed.

In another aspect, in the above-mentioned electric motor drive control device, the drive control unit includes a current control system that controls the drive current of the electric motor and a speed control system that controls the speed of the electric motor, and the compensation value generation unit determines whether to generate the compensation value based on the frequency of the pulsating torque, a first frequency band of the current control system in which the current control system can follow the pulsating torque, and a second frequency band of the speed control system in which the speed control system can follow the pulsating torque, and generates the compensation value when it is determined to generate the compensation value. Preferably, in the above-described electric motor drive control device, the compensation value generating unit determines not to generate the compensation value, firstly, when neither a frequency of a first pulsating torque in the pulsating torque exceeds a first frequency band nor a frequency of a second pulsating torque in the pulsating torque exceeds a first frequency band, and secondly, when at least one of a frequency of the first pulsating torque in the pulsating torque exceeds the first frequency band and a frequency of the second pulsating torque in the pulsating torque exceeds the first frequency band and the frequency of the first pulsating torque in the pulsating torque exceeds a second frequency band and the frequency of the second pulsating torque in the pulsating torque exceeds a first frequency band, In any of the cases where the frequency of the pulsating torque exceeds the second frequency band, it is determined to generate the compensation value to be used on the input side of the drive control unit, and thirdly, in at least any of the cases where the frequency of a first pulsating torque in the pulsating torque exceeds the first frequency band and the frequency of a second pulsating torque in the pulsating torque exceeds the first frequency band, and also in at least any of the cases where the frequency of the first pulsating torque in the pulsating torque exceeds the second frequency band and the frequency of the second pulsating torque in the pulsating torque exceeds the second frequency band, it is determined to generate the compensation value to be used in the output of the drive control unit. Preferably, the drive control unit is a device that controls the electric motor by feedback control according to a control target, and includes a current command generation unit that generates a d-axis current command value and a q-axis current command value based on the control target, a deviation generation unit that generates each deviation between the d-axis current command value and the q-axis current command value generated by the current command generation unit and a d-axis current value and a q-axis current value corresponding to a current value supplied to the electric motor, and a current control unit that generates a d-axis voltage command value and a q-axis voltage command value based on the each deviation generated by the deviation generation unit, and when the compensation value generation unit determines to generate the compensation value to be used on the input side of the drive control unit, the compensation value is used for the input of the current control unit, and when it determines to generate the compensation value to be used for the output of the drive control unit, the compensation value is used for the output of the current control unit. Preferably, the motor is a permanent magnet synchronous motor (PMSM), the control target of the d-axis is a constant 0, and when the compensation value generating unit determines to generate the compensation value to be used on the input side of the drive control unit, the compensation value is used only for the q-axis current, and when the compensation value generating unit determines to generate the compensation value to be used on the output side of the drive control unit, the compensation value is used only for the q-axis voltage. Preferably, the permanent magnet synchronous motor (PMSM) includes a surface permanent magnet synchronous motor (SPMSM).

Such an electric motor drive control device determines whether or not to generate the compensation value based on the frequency of the pulsating torque, the first frequency band, and the second frequency band, and can therefore generate the compensation value appropriately.

In another aspect, in the above-mentioned electric motor drive control device, the compensation value generation unit does not generate the compensation value when a voltage value corresponding to a control command value based on the compensation value exceeds a predetermined output voltage value of a power source that supplies power to the electric motor.

This type of motor drive control device controls the motor within the rated voltage value of the power supply, preventing control instability.

An electric motor drive control method according to another aspect of the present invention is a method for controlling an electric motor, and includes a pulsating torque estimation step for estimating the pulsating torque that will occur at the next control timing by using a pulsating model that represents a pulsating torque whose magnitude increases and decreases over time, a compensation value processing step for determining a compensation value for canceling the pulsating torque estimated in the pulsating torque estimation step, and a drive control step for controlling and driving the electric motor with a control command value based on the compensation value determined in the compensation value processing step, and the pulsating torque includes at least one of a first pulsating torque caused by a spatial high-frequency component of the magnetomotive force distribution in the circumferential direction of the electric motor, and a second pulsating torque that is a cogging torque.

This motor drive control method estimates the pulsating torque that will occur at the next control timing and generates a compensation value to cancel out this estimated pulsating torque, so that the pulsating torque, including at least one of the first and second pulsating torques that occur in the motor itself, can be more appropriately suppressed.

An electric motor drive control system according to another aspect of the present invention includes an electric motor and an electric motor drive control unit that controls the electric motor, and the electric motor drive control unit is any one of the electric motor drive control devices described above.

This makes it possible to provide an electric motor drive control system equipped with any one of the electric motor drive control devices described above. Since such an electric motor drive control system is equipped with any one of the electric motor drive control devices described above, it can more appropriately suppress pulsating torque, including at least one of the first and second pulsating torques generated in the electric motor itself.

The motor drive control device and the motor drive control method according to the present invention can more appropriately suppress pulsating torque. According to the present invention, it is possible to provide an electric motor drive control system equipped with the electric motor drive control device.

1 is a block diagram showing a configuration of an electric motor drive control system according to an embodiment; 2 is a circuit diagram showing a configuration of an inverter circuit in the electric motor drive control system. FIG. FIG. 2 is a block diagram of a current control system. FIG. 2 is a block diagram of a speed control system. 4 is a flowchart showing an operation of the electric motor drive control system. 10 is a flowchart showing an operation of the electric motor drive control system in a modified embodiment.

One or more embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. Note that components with the same reference numerals in each drawing are the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

The motor drive control system in the embodiment is a system that drives and controls the motor, and includes, for example, an electric motor and an electric motor drive control unit that controls the electric motor. The electric motor drive control unit includes a pulsating torque estimation unit that estimates the pulsating torque that will occur at the next control timing by using a pulsating model that represents a pulsating torque whose magnitude increases and decreases over time, a compensation value generation unit that generates a compensation value for canceling the pulsating torque estimated by the pulsating torque estimation unit, and a drive control unit that controls and drives the electric motor with a control command value based on the compensation value generated by the compensation value generation unit. Here, the pulsating torque includes at least one of a first pulsating torque caused by a spatial high-frequency component of the magnetomotive force distribution in the circumferential direction of the electric motor, and a second pulsating torque that is a cogging torque. The electric motor drive control system including such an electric motor drive control unit will be described in more detail below.

Figure 1 is a block diagram showing the configuration of an electric motor drive control system in an embodiment. Figure 2 is a circuit diagram showing the configuration of an inverter circuit in the electric motor drive control system. Figure 3 is a block diagram of a current control system. Figure 4 is a block diagram of a speed control system.

As shown in FIG. 1, the electric motor drive control system S in the embodiment includes an electric motor M, an inverter circuit IV, a PWM modulator PW, a two-phase to three-phase conversion unit CV1, a drive control unit DC, a three-phase to two-phase conversion unit CV2, a rotation speed processing unit RSC, a current measurement unit CS, a rotation angle measurement unit VS, a pulsating torque estimation unit PT, and a compensation value generation unit CV.

The electric motor M is connected to the inverter circuit IV and is driven by the AC output of the inverter circuit IV. For example, the electric motor M is a synchronous motor driven by three-phase AC power of U-phase, V-phase, and W-phase output from the inverter circuit IV, more specifically, in this embodiment, it is a surface mounted permanent magnet synchronous motor (SPMSM), and its speed control is the subject. Note that the electric motor M is not limited to this, and may be, for example, another type such as an induction motor (IM) or a switched reluctance motor (SRM).

The PWM modulator PW is a circuit that outputs a rectangular wave with a changeable pulse width, and the inverter circuit IV is a circuit that converts DC power to AC power. In this embodiment, the PWM modulator PW and the inverter circuit IV constitute a so-called three-phase PWM inverter motor driver that drives an electric motor with three-phase AC power. The PWM modulator PW and the inverter circuit IV are connected to the drive control unit DC via the two-phase to three-phase conversion unit CV1, and convert the DC power from the DC power source Vdc into AC power of a predetermined frequency according to the control of the drive control unit DC. More specifically, the PWM modulator PW is a circuit that outputs a rectangular wave with a frequency and pulse width according to the control of the drive control unit DC as a control signal (IV control signal) to the inverter circuit IV. The inverter circuit IV is a circuit that is connected to the PWM modulator PW, and converts the DC power of the DC power source Vdc into AC power of a predetermined frequency according to the IV control signal from the PWM modulator PW. The inverter circuit IV includes, for example, three sets of switching elements Tr1, Tr4; Tr2, Tr5; Tr3, Tr6, each set including two switching elements Tr connected in series, which are connected in parallel to each other, as shown in FIG. 2. More specifically, the inverter circuit IV includes six switching elements Tr1 to Tr6. These first to sixth switching elements Tr1 to Tr6 are power semiconductor elements having an on/off switch function, such as insulated gate bipolar transistors (IGBTs). One terminal (e.g., each collector terminal) of each of the first to third switching elements Tr1 to Tr3 is connected to one terminal of a DC power supply Vdc. The other terminal (e.g., emitter terminal) of the first switching element Tr1 is connected to one terminal (e.g., each collector terminal) of the fourth switching element Tr4. The other terminal (e.g., emitter terminal) of the second switching element Tr2 is connected to one terminal (e.g., each collector terminal) of the fifth switching element Tr5. The other terminal (e.g., emitter terminal) of the third switching element Tr3 is connected to one terminal (e.g., each collector terminal) of the sixth switching element Tr6. The other terminals (e.g., each emitter terminal) of the fourth to sixth switching elements Tr4 to Tr6 are connected to the other terminal of the DC power supply Vdc. In the first to sixth switching elements Tr1 to Tr6, each control terminal (e.g., gate terminal) to which an IV control signal for turning on and off the switching element Tr is input is connected to the PWM modulator PW. In each of the first to sixth switching elements Tr1 to Tr6, a diode D1 to D6 is connected to the other terminal, with the anode terminal connected to the other terminal. A first connection point connecting the first switching element Tr1 and the fourth switching element Tr4 outputs, for example, a U-phase AC current and is connected to an input terminal connecting the U-phase of the electric motor M. The second connection point connecting the second switching element Tr2 and the fifth switching element Tr5 outputs, for example, a V-phase AC current and is connected to an input terminal connecting the V-phase of the motor M. The third connection point connecting the third switching element Tr3 and the sixth switching element Tr6 outputs, for example, a W-phase AC current and is connected to an input terminal connecting the W-phase of the motor M. In this configuration, the inverter circuit IV is a so-called two-level three-phase inverter circuit, and one switching element Tr1, Tr2, Tr3 of each set and the other switching element Tr4, Tr5, Tr6 are controlled according to an IV control signal from the PWM modulator PW so that they have mutually opposite switching modes (when one is on, the other is off, and when one is off, the other is on), and the DC power of the DC power source Vdc is converted to output three-phase AC current of the U-phase, V-phase, and W-phase to the motor M.

The current measurement unit CS is connected to the three-phase to two-phase conversion unit CV2, and is a device that measures the currents flowing from the inverter circuit IV to the motor M, which in this embodiment are the U-phase current, the V-phase current, and the W-phase current, and outputs each measurement result to the three-phase to two-phase conversion unit CV2. The current measurement unit CS is configured to include, for example, an AC ammeter.

The rotation angle measurement unit VS is connected to the two-phase to three-phase conversion unit CV1, the three-phase to two-phase conversion unit CV2, the rotation speed processing unit RSC, and the pulsation torque estimation unit PT, and is a device that measures the magnetic pole position of the electric motor M in terms of angle and outputs the measurement results (rotation angle, electrical angle (= mechanical angle/number of pole pairs of the electric motor M)) to the two-phase to three-phase conversion unit CV1, the three-phase to two-phase conversion unit CV2, the rotation speed processing unit RSC, and the pulsation torque estimation unit PT. The rotation angle measurement unit VS is configured with, for example, a rotary encoder (pulse generator), a Hall IC, etc. In the case of a sensorless system, the rotation angle measurement unit VS may determine the rotation angle of the electric motor M from the current and voltage using a model of the electric motor M.

The two-phase to three-phase conversion unit CV1 is connected to the drive control unit DC, and determines a control signal (PWM ^control signal) for controlling the PWM modulator PW from the measurement result (rotation angle) input from the rotation angle measurement unit _VS and the voltage command values _vd ^* , _vq ^* generated by the drive control unit DC so that the U-phase current, V-phase current and W-phase current corresponding to the voltage command values vd ^* , _vq * are output from the inverter circuit IV, and outputs this PWM control signal to the PWM modulator PW.

The three-phase to two-phase conversion unit CV2 is connected to the drive control unit DC, and determines the excitation current (d-axis current) i d and the torque component current (q-axis current) i q by the so-called Clarke transformation and Park transformation from the measurement results (U-phase current, V-phase current, and W-phase current) input from the current measurement unit _CS and the measurement results (rotation angle) input from the rotation angle measurement unit _VS , and outputs the determined d-axis current i _d and q-axis current i _q to the drive control unit DC.

The rotation speed processing unit RSC is connected to the drive control unit DC, and determines the rotation speed _ωm of the electric motor M from the measurement result (rotation angle) input from the rotation angle measurement unit VS, and outputs the determined rotation speed _ωm to the drive control unit DC. For example, the rotation speed ωm can be determined by time-differentiating the rotation angle _θe measured by the rotation angle measurement unit VS and multiplying _it by the reciprocal of the number p of pole pairs of the electric motor M.

The drive control unit DC controls and drives the electric motor M with a control command value based on a compensation value generated by a compensation value generating unit CV as described later. More specifically, the drive control unit DC is a device that controls the electric motor M with feedback control according to a control target, and includes current command generating units GId, GIq that generate d-axis current command values and q-axis current command values based on the control target, deviation generating units SM2d, SM2q that generate deviations between the d-axis current command values and q-axis current command values generated by the current command generating units GId, GIq and the d-axis current values and q-axis current values corresponding to the current values supplied to the electric motor M by subtracting the d-axis current values and q-axis current values from the d-axis current command values and q-axis current command values, respectively, and current control units GVd, GVq that generate d-axis voltage command values and q-axis voltage command values based on the deviations generated by the deviation generating units SM2d, SM2q, for example, by so-called PI control. In this embodiment, the motor M is a permanent magnet synchronous motor (PMSM), more specifically, a surface permanent magnet synchronous motor (SPMSM), so that only the q-axis contributes to the torque, the control target of the d-axis is always a constant 0, and the d-axis current command generating unit GId is omitted as shown in Fig. 1. Therefore, this d-axis control target 0 is input to the d-axis deviation generating unit SM2d. As shown in Fig. 1, the q-axis current command generating unit GIq includes a deviation generating unit SM1q that calculates the deviation between the control target _ωm ^* (k) and the rotation speed _ωm of the motor M calculated by the rotation speed processing unit RSC by subtracting the rotation speed _ωm of the motor M from the control target _ωm ^* (k), and a generating unit PI that generates a q-axis current command value according to the deviation calculated by the deviation generating unit SM1q, for example, by PI control.

The drive control unit DC configured in this way includes a current control system that controls the drive current of the electric motor M and a speed control system that controls the speed of the electric motor M.

The pulsating torque estimator PT is connected to the compensation value generator CV, and estimates the pulsating torque occurring at the next control timing by using a pulsating model representing a pulsating torque whose magnitude increases and decreases over time. The pulsating torque includes, for example, at least one of a first pulsating torque caused by a spatial high-frequency component of the magnetomotive force distribution in the circumferential direction of the motor M, and a second pulsating torque which is a cogging torque. In this embodiment, the pulsating torque _Tdist is modeled to include both the first and second pulsating torques _pn and _Tcog , as shown in the following formula 1, but the pulsating torque _Tdist may be modeled by omitting one of them depending on, for example, the specifications of the motor drive control system S.

Here, i _d (k) is the d-axis current in the k-th control, i _q (k) is the q-axis current in the k-th control, and θ _e (k) is the rotation angle of the motor M in the k-th control. _{φ dh} (θ _e ) is the harmonic component of the flux linkage on the d-axis, and φ _qh (θ _e ) is the harmonic component of the flux linkage on the q-axis. The first term of this formula 1 represents the first pulsating torque p _n , and the second term of this formula 1 represents the second pulsating torque T _cog . This first pulsating torque p _n is generated, for example, by deviation from an ideal state in which the magnetomotive force distribution in the circumferential direction of the motor M is a sine curve.

φ _dh (θ _e ) and φ _qh (θ _e ) in this first pulsating torque p _n are obtained, for example, by detecting back electromotive voltage values v _d and v _q obtained by driving the electric motor M under no load and using these values in the following equation 2, thereby obtaining the first pulsating torque p _n . Ψ is the differential magnetic flux of the permanent magnet in the electric motor M. Alternatively, for example, φ _dh (θ _e ) and φ _qh (θ _e ) can be obtained by a simulation simulating a similar driving state or by so-called FEM analysis.

The second pulsating torque T _cog can be obtained, for example, by detecting a thrust value obtained by driving the electric motor M under no load in a similar manner. Alternatively, for example, the second pulsating torque T _cog can be obtained by a simulation simulating a similar driving state, or by so-called FEM analysis.

In this embodiment, the pulsating torque T _dist, which varies depending on the rotation angle θ _e (k) of the motor M, is estimated by the pulsating model of the above-mentioned formula 1, and a compensation value for canceling the estimated pulsating torque T _dist is added to the control command, thereby suppressing the pulsating torque T _dist . Here, the pulsating torque T _dist estimated from the rotation angle θ _e (k) detected by the rotation angle measurement unit VS is an estimated value of the pulsating torque T _dist generated at the current rotation angle θ _e (k), and since a processing time is actually required to generate the compensation value, at least one control cycle of the processing time has elapsed, and a delay in the processing time occurs between the estimated value of the pulsating torque T _dist and the pulsating torque T _{dist that} is actually generated, and a mismatch due to this delay occurs between them. In particular, when rotating at high speed, this mismatch significantly affects the control, making it difficult to suppress the pulsating torque T _dist . In order to suppress the pulsating torque T _dist , it is necessary to compensate for this delay, and in this embodiment, the delay of the rotation angle θ _e (k) used to estimate the pulsating torque T _dist is compensated for. In this embodiment, the delay (the processing time) is set to one control cycle T _s , and the rotation angle θ _e (k+1) after one control cycle T _s has elapsed is estimated by the following equation 3, and the estimated value θ _e (k+1) of the rotation angle is used to estimate the pulsating torque T _dist , thereby compensating for the delay. Note that in the case of the kth control, (k+1), (k+2), (k+3), ... represent predicted values.

Therefore, in this embodiment, the pulsating torque estimation unit PT includes a rotation angle estimation unit DA that is connected to a rotation angle measurement unit VS and that estimates a rotation angle θ _e (k+1) after one control period _Ts based on the rotation angle θ _e (k) of the electric motor M measured by the rotation angle measurement unit VS using the above equation 3, a first pulsating torque estimation unit PN that is connected to the rotation angle estimation unit DA and that estimates a first pulsating torque p _n based on the rotation angle θ _e (k+1) after one control period _Ts estimated by the rotation angle estimation unit DA and corresponds to the first term of the above equation 1, a second pulsating torque estimation unit TC that is connected to the rotation angle estimation unit DA and that estimates a second pulsating torque T _cog based on the rotation angle θ _e (k+1) after one control _period Ts estimated by the rotation angle estimation unit DA and corresponds to the second term of the above equation 1, and and an adding section SM that adds _n to the second pulsating torque T _cog estimated by the second pulsating torque estimating section TC.

The compensation value generation unit CV generates a compensation value to cancel the pulsating torque estimated by the pulsating torque estimation unit PT.

In this embodiment, when the frequency of the pulsating torque T _dis is low, the drive control unit DC itself can cancel the pulsating torque T _dis , so in such a case, the compensation value generating unit CV does not generate the compensation value. More specifically, each closed-loop transfer function is calculated using the control command values of each control system of the current and speed in the drive control unit DC as inputs, and the possibility of generating a compensation value and the input location of the compensation value are determined according to each cutoff frequency (cut-off frequency). That is, the compensation value generating unit CV determines whether to generate the compensation value based on the frequency of the pulsating torque, a first frequency band of the current control system in which the current control system of the drive control unit DC can follow the pulsating torque, and a second frequency band of the speed control system in which the speed control system of the drive control unit DC can follow the pulsating torque, and generates the compensation value when it is determined to generate the compensation value.

More specifically, the current control system is approximated as shown in Fig. 3, for example, and includes a subtractor 11 that determines a deviation between a q-axis current _iq ^* of a control target and a q-axis current _iq of a motor M by subtracting the q-axis current _iq of the motor M from the q-axis current _iq ^* of the control target, a controller 12 that feedback controls the motor M based on the deviation determined by the subtractor 11, and an electric circuit 13 of the motor M controlled by the controller 12. The controller 12 is expressed, for example, by _kPi + _kIi /s, and the electric circuit 13 of the motor M is expressed, for example, by 1/(Ls+R).

The closed-loop transfer function G _iq (s) from the q-axis current i _q ^* of the control target to the actual current i _q in this current control system is expressed by the following equation 4. For example, if k _Pi = ω _cfi × L and k _Ii = k _Pi × (R/L), then it is expressed by the following equation 5.

Here, L is the inductance of the winding of the motor M, R is the resistance of the winding of the motor M, and _ωcfi is the cutoff frequency of the current control system. s is the Laplace transform operator. The above-mentioned gain setting of _kPi = _ωcfi × L and _kIi = _kPi × (R/L) is one example, and the cutoff frequency can be obtained from the above formula 4 even with other gain settings.

From the above formula 5, the current control system has a first-order lag of the cutoff frequency ω _cfi . Therefore, in frequencies equal to or lower than the cutoff frequency ω _cfi (first frequency band FW1; 0<FW1≦ω _cfi ), this current control system can follow the time change of the controlled object and can cancel the pulsating torque.

Similarly, the speed control system is approximated as shown in Fig. 4, for example, and includes a subtractor 21 that obtains a deviation between a rotation speed _ωm ^* of a control target and a rotation speed _ωm of the electric motor M by subtracting the rotation speed _ωm of the electric motor M from the rotation speed _ωm ^* of the control target, a controller 22 that feedback controls the electric motor M based on the deviation obtained by the subtractor 21, and an electric circuit 23 of the electric motor M controlled by the controller 22. The controller 22 is expressed as _kPs + _kIs /s, for example, and the electric circuit 23 of the electric motor M is expressed as 1/Js, for example. J is the moment of inertia of the electric motor M. The disturbance torque _Td is mixed (added) into the output of the controller 22. However, it was assumed that the frequency response of the speed control system was sufficiently smaller than that of the current control system.

A closed loop transfer function G _is (s) from the control target rotational speed ω _m ^* to the actual rotational speed ω _m in this speed control system is expressed by the following equation 6, and for example, when k _Ps = ω _cfs × J, it is expressed by the following equation 7. Furthermore, a transfer function from the disturbance torque T _d to the actual rotational speed ω _m is expressed by the following equation 8.

From the above equation 8, at frequencies below the cutoff frequency ω _cfs (second frequency band FW2; 0<FW2≦ω _cfs ), this speed control system can follow the time changes of the controlled object and can cancel the disturbance torque T _d , that is, the pulsating torque in this embodiment.

On the other hand, the first and second pulsating torques _pn and _Tcog are generated with a period that depends on the rotation speed of the motor M. The frequency _fmag of the first pulsating torque _pn is expressed by the following equation 9, assuming that its main component is of order m. It is generally known that m=6 for a surface-type permanent magnet synchronous motor (SPMSM) with concentrated windings. The period of the rotation angle at which the second pulsating torque _Tcog is generated is expressed by the following equation 10, and the frequency _fcog of the second pulsating torque _Tcog is expressed by the following equation 11 from the rotation speed. It is to be noted that n _s is the number of slots of the motor M, and lcm(A,B) is an operator for finding the least common multiple with A to B.

From the above, when the frequency f _mag of the first pulsating torque _pn is equal to or lower than the cutoff frequency _ωcfi of the current control system (2πf _mag ≦ _ωcfi ), the first pulsating torque _pn can be followed by this current control system, whereas when the frequency f _mag of the first pulsating torque _pn exceeds the cutoff frequency _ωcfi of the current control system (2πf _mag > _ωcfi ), the first pulsating torque _pn can be cancelled out by using a compensation value on the input side of the drive control unit DC, which in the example shown in FIG. 1 is the input to the current control unit GVq. When the frequency f _cog of the second pulsating torque T _cog is equal to or lower than the cutoff frequency ω _cfi of the current control system (2πf _cog ≦ ω _cfi ), the second pulsating torque T _cog can be followed by this current control system, and when the frequency f _cog of the second pulsating torque T _cog exceeds the cutoff frequency ω _cfi of the current control system (2πf _cog > ω _cfi ), the second pulsating torque T _cog can be cancelled by using a compensation value on the input side of the drive control unit DC, in the example shown in FIG. 1 , the input of the current control unit GVq. Similarly, when the frequency f _mag of the first pulsating torque p _n is equal to or lower than the cutoff frequency ω _cfs of the speed control system (2πf _mag ≦ ω _cfs ), the first pulsating torque p _n can be followed by this speed control system, and when the frequency f _mag of the first pulsating torque p _n exceeds the cutoff frequency ω _cfs of the speed control system (2πf _mag > ω _cfs ), the first pulsating torque p _n can be canceled out by using a compensation value in the output of the drive control unit DC, which in the example shown in FIG. 1 is the output of the current control unit GVq. When the frequency f _cog of the second pulsation torque T _cog is equal to or lower than the cutoff frequency ω _cfs of the speed control system (2πf _cog ≦ ω _cfs ), the second pulsation torque T _cog can be followed by this speed control system. When the frequency f _cog of the second pulsation torque T _cog exceeds the cutoff frequency ω _cfs of the speed control system (2πf _cog > ω _cfs ), the second pulsation torque T _cog can be cancelled by using a compensation value in the output of the drive control unit DC, which in the example shown in FIG. 1 is the output of the current control unit GVq.

The compensation value generation unit CV therefore comprises, more specifically, a first variable amplifier unit VA1, a second variable amplifier unit VA2, a first subtraction unit SM3, a second subtraction unit SM4, and a gain control unit GC, as shown in FIG. 1.

The first variable amplifier VA1 has an input connected to the adder SM of the pulsating torque estimation unit PT and amplifies the pulsating torque T _dis estimated by the pulsating torque estimation unit PT with a gain K _TI to generate a compensation value for the q-axis current command value for canceling the pulsating torque T _dis estimated by the pulsating torque estimation unit PT. The first variable amplifier VA1 has an output connected to the first subtraction unit SB3 and outputs a compensation value for the d-axis current command value to the first subtraction unit SB3.

The second variable amplifier VA2 has an input connected to the adder SM of the pulsating torque estimation unit PT and amplifies the pulsating torque T _dis estimated by the pulsating torque estimation unit PT with a gain K _IV to generate a compensation value for the q-axis voltage command value for canceling the pulsating torque T _dis estimated by the pulsating torque estimation unit PT. The second variable amplifier VA2 has an output connected to the second subtraction unit SB4 and outputs the compensation value for the q-axis voltage command value to the second subtraction unit SB4.

The first subtraction unit SB3 is interposed between the deviation generation unit SM2q and the current control unit GVq, and subtracts a compensation value for the q-axis current command value generated by the first variable amplification unit VA1 from the deviation generated by the deviation generation unit SM2q. By performing the subtraction, the compensation value for the q-axis current command value generated by the first variable amplification unit VA1 is incorporated into the deviation generated by the deviation generation unit SM2q so as to cancel the pulsating torque _Tdis estimated by the pulsating torque estimation unit PT.

The second subtraction unit SB4 is interposed between the current control unit GVq and the two-phase to three-phase conversion unit CV1, and subtracts a compensation value for the d-axis voltage command value generated by the second variable amplification unit VA2 from the q-axis voltage command value generated by the current control unit GVq. By performing the subtraction, the compensation value for the q-axis voltage command value generated by the second variable amplification unit VA2 is incorporated into the q-axis voltage command value generated by the current control unit GVq so as to cancel the pulsation torque _Tdis estimated by the pulsation torque estimation unit PT.

In this way, even if a compensation value is input to the input of the current control unit GVq, the pulsating torque cannot be fully compensated for. In this embodiment, the compensation value is directly input to the output of the current control unit GVq.

The gain control section GC is connected to each of the first and second variable amplification sections VA1, VA2, and controls the gains _KTI , _KIV of the first and second variable amplification sections VA1, VA2.

More specifically, first, when neither the frequency f _mag of the first pulsating torque p _n in the pulsating torque T _dis exceeds the first frequency band FW1 (2πf _mag > ω _cfi ) nor the frequency f _{cog of the second pulsating torque T cog in} the pulsating torque T _dis exceeds the first frequency band FW1 (2πf _cog > ω _cfi ), the drive control unit DC can follow and so the gain control unit GC determines not to generate the compensation values (the compensation value for the q-axis current command value and the compensation value for the q-axis voltage command value). That is, the gain control unit GC controls the gains K _TI and K _IV of the first and second variable amplification units VA1 and VA2 to 0 (K _TI = 0, K _IV = 0).

Secondly, the gain control unit GC detects at least one of a case where the frequency f _mag of the first pulsating torque p _n in the pulsating torque T _dis exceeds the first frequency band FW1 (2πf _mag > ω _cfi ) and a case where the frequency f _cog of the second pulsating torque T _cog in the pulsating torque T _dis exceeds the first frequency band FW1 (2πf _cog > ω _cfi ), and a case where the frequency f _mag of the first pulsating torque p _n in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _mag > ω _cfs ) and a case where the frequency f _cog of the second pulsating torque T _cog in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _cog > ω _cfs 1, the gain control unit GC determines to generate the compensation value (compensation value for the q-axis current command value) to be used on the input side of the drive control unit DC, that is, the input of the current control unit GVq in the example shown in Fig. 1. That is, the gain control unit GC controls the gain _KTI of the first variable amplifier unit VA1 to a value described below, and controls the gain _KIV of the second variable amplifier unit VA2 to 0 ( _KTI ≠ 0, _KIV = 0). As a result, the compensation value for the q-axis current command value is used for the input of the current control unit GVq, and the first subtraction unit SB3 subtracts the compensation value for the q-axis current command value generated by the first variable amplifier unit VA1 from the deviation generated by the deviation generation unit SM2q.

Thirdly, the gain control unit GC _detects at least one of a case where the frequency f _mag of the first pulsating torque p _n in the pulsating torque T dis exceeds the first frequency band FW1 (2πf _mag > ω _cfi ) and a case where the frequency f _cog of the second pulsating torque T _cog in the pulsating torque T _dis exceeds the first frequency band FW1 (2πf _cog > ω _cfi ), and a case where the frequency f _mag of the first pulsating torque p _n in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _mag > ω _cfs ) and a case where the frequency f _cog of the second pulsating torque T _cog in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _cog > ω _cfs 1, the gain control unit GC determines to generate the compensation value (compensation value for the q-axis voltage command value) to be used in the output of the drive control unit DC, in the example shown in Fig. 1, the output of the current control unit GVq. That is, the gain control unit GC controls the gain _KTI of the first variable amplification unit VA1 to 0, and controls the gain _KIV of the second variable amplification unit VA2 to a value described later ( _KTI = 0, _KIV ≠ 0). As a result, the compensation value for the q-axis voltage command value is used in the output of the current control unit GVq, and the second subtraction unit SB4 subtracts the compensation value for the q-axis voltage command value generated by the second variable amplification unit VA2 from the q-axis voltage command value generated by the current control unit GVq.

Here, the gains _KTI and _KIV of the first and second variable amplifiers VA1 and VA2 may be obtained and set by tuning, for example, but may also be obtained by the following formulas 12 and 13. Formula 12 for obtaining the gain _KTI is set so as to obtain a current for canceling the pulsating torque _Tdis estimated by the pulsating torque estimation unit PT based on the pulsating torque _Tdis estimated by the pulsating torque estimation unit PT and the characteristic parameters p and Ψ of the motor M. Formula 13 for obtaining the gain _KIV is set so as to convert the gain _KTI into a voltage. Here, _kTI and _kIV are adjustment parameters for adjusting deviations caused by the difference between the design value and the actual value of the motor M and the inductance L of the windings not being taken into consideration when converting the gain _KTI into a voltage, and are appropriately set in advance.

Such pulsating torque estimation unit PT, compensation value generation unit CV, drive control unit DC, 2-phase to 3-phase conversion unit CV1, 3-phase to 2-phase conversion unit CV2 and rotational speed processing unit RSC can be configured by a microprocessor equipped with a CPU (Central Processing Unit), memory and its peripheral circuits, and the pulsating torque estimation unit PT, compensation value generation unit CV, drive control unit DC, 2-phase to 3-phase conversion unit CV1, 3-phase to 2-phase conversion unit CV2 and rotational speed processing unit RSC are functionally configured in the CPU by execution of a predetermined program. At this time, the rotation angle estimation unit DA, first pulsation torque estimation unit PN, second pulsation torque estimation unit TC and addition unit SM in the pulsation torque estimation unit PT, the gain control unit GC, first variable amplification unit VA1, second variable amplification unit VA2, first subtraction unit SB3 and second subtraction unit SB4 in the compensation value generation unit CV, and the current command generation unit GIq (deviation generation unit SM1q, generation unit PI), deviation generation units SM2d, SM2q and current control units GVd, GVq in the drive control unit DC are functionally configured in the CPU.

Next, the operation of this embodiment will be described. Figure 5 is a flowchart showing the operation of the electric motor drive control system.

When the power is turned on in such an electric motor drive control system S, the necessary parts are initialized and start to operate. Then, for example, by executing a program, the CPU is functionally configured with a pulsating torque estimation part PT, a compensation value generation part CV, a drive control part DC, a two-phase to three-phase conversion part CV1, a three-phase to two-phase conversion part CV2, and a rotation speed processing part RSC, the pulsating torque estimation part PT is functionally configured with a rotation angle estimation part DA, a first pulsating torque estimation part PN, a second pulsating torque estimation part TC, and an addition part SM, the compensation value generation part CV is functionally configured with a gain control part GC, a first variable amplification part VA1, a second variable amplification part VA2, a first subtraction part SB3, and a second subtraction part SB4, and the drive control part DC is functionally configured with a current command generation part GIq (deviation generation part SM1q, generation part PI), deviation generation parts SM2d, SM2q, and current control parts GVd, GVq.

Regarding the control for canceling the pulsating torque, the processes S1 to S8 shown in FIG. 5 are repeatedly executed at predetermined control periods _Ts until the driving of the electric motor M is stopped.

In FIG. 5, the electric motor drive control system S acquires the rotation angle θ _e (k) of the electric motor M from the rotation angle measurement unit VS by the rotation angle estimation unit DA of the pulsating torque estimation unit PT (S1).

Next, the motor drive control system S estimates the rotation angle θ _e (k+1) after one control period _Ts (the rotation angle θ _e (k+1) at the next control timing) by the rotation angle estimator DA (S2).

In the electric motor drive control system S, a first pulsating torque estimation section PN of the pulsating torque estimation section PT estimates a first pulsating torque _pn based on the rotation angle _θe (k+1) after one control period _Ts estimated by the rotation angle estimation section DA in the process S2, a second pulsating torque estimation section PN of the pulsating torque estimation section PT estimates a second pulsating torque _pcog based on the rotation angle _θe (k+1), and an adder SM of the pulsating torque estimation section PT adds up the first and second pulsating torques _pn and _Tcog to thereby estimate a pulsating torque _Tdis (= _pn + _Tcog ) (S3). The estimated pulsating torque is output from the adder SM to each of the first and second variable amplifier sections VA1 and VA2 in the compensation value generation section CV.

Next, the motor drive control system S determines whether or not the frequency _fmag of the first pulsating torque _pn in the pulsating torque Tdis exceeds the first frequency band FW1 ( _2πfmag > _ωcfi ) or _{the frequency fcog of the second pulsating torque Tcog in the pulsating torque Tdis exceeds} the first frequency band FW1 ( _2πfcog > _ωcfi ) (S4). If the result of this determination is not either of the above cases (No), the motor drive control system S then executes process S5 and then ends this process at the current control timing. On the other hand, if the result of the judgment is at least one of the above cases (Yes, any of the cases of 2πf _mag > ω _cfi , 2πf _cog > ω _cfi , or 2πf _mag > ω _cfi and 2πf _cog > ω _cfi ), the motor drive control system S then executes process S6.

In this process S5, the electric motor drive control system S controls the gains _KTI , _KIV of the first and second variable amplifiers VA1, VA2 to 0 ( _KTI = 0, _KIV = 0) by the gain control unit GC of the compensation value generating unit CV. Therefore, the pulsating torque _Tdis is reduced by the drive control unit DC.

In the process S6, the motor drive control system S determines whether or not the frequency f _mag of the first pulsating torque p _n in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _mag > ω _cfs ) or the frequency f _cog of the second pulsating torque T _cog in the pulsating torque T _dis exceeds the second frequency band FW2 (2πf _cog > ω _cfs ). If the result of this determination is not either of the above cases (No), the motor drive control system S then executes process S7 and then ends this process at the current control timing. On the other hand, if the result of the judgment is at least one of the above cases (Yes, any of the cases of 2πf _mag > ω _cfs , 2πf _cog > ω _cfs , or 2πf _mag > ω _cfs and 2πf _cog > ω _cfs ), the motor drive control system S then executes process S8 and then terminates this process at the current control timing.

In this process S7, the electric motor drive control system S uses the gain control unit GC to determine the gain _KTI of the first variable amplifier unit VA1 using the above-mentioned equation 12, controls the first variable amplifier unit VA1 to become the determined gain _KTI , and controls the gain _KIV of the second variable amplifier unit VA2 to be 0 ( _KTI ≠ 0, _KIV = 0). By executing this process S7, the compensation value of the q-axis current command value is used as the input of the current control unit GVq, and the first subtraction unit SB3 subtracts the compensation value of the q-axis current command value generated by the first variable amplifier unit VA1 from the deviation generated by the deviation generation unit SM2q, whereby the pulsating torque _Tdis is reduced by the compensation value of the q-axis current command value.

In the process S8, the motor drive control system S controls the gain _KTI of the first variable amplifier VA1 to 0 by the gain control unit GC, and calculates the gain _KIV of the second variable amplifier VA2 by the above-mentioned formula 13 and controls it to a value as described below ( _KTI = 0, _KIV ≠ 0). Note that in order to calculate the gain _KIV by the above-mentioned formula 13, the gain _KTI is calculated by the above-mentioned formula 12, but the gain _KTI of the first variable amplifier VA1 is controlled to 0 as described above. By executing this process S8, the compensation value of the q-axis voltage command value is used for the output of the current control unit GVq, and the second subtraction unit SB4 subtracts the compensation value of the q-axis voltage command value generated by the second variable amplifier VA2 from the q-axis voltage command value generated by the current control unit GVq, thereby reducing the pulsating torque _Tdis by the compensation value of the q-axis voltage command value.

As described above, the motor drive control system S, motor drive control device, and motor drive control method implemented therein in this embodiment estimate the pulsating torque T _dis generated at the next control timing and generate a compensation value for canceling this estimated pulsating torque T _dis , so that the pulsating torque T dis including at least one of the first and second pulsating torques p _n and T _cog generated in the motor M itself (in the above description, both ₎ can be more appropriately suppressed. Therefore, the motor drive control system S, motor drive control device, and motor drive control method described above can achieve low vibration and low noise, and can more accurately track the target speed and target position.

The above-mentioned motor drive control system S, motor drive control device, and motor drive control method determine whether or not to generate the compensation value based on the pulsating torque T _dis , in the above-mentioned first and second pulsating torques p _n and T _cog, respectively, and the frequencies f _mag and f _cog , the first frequency band FW1, and the second frequency band FW2, and therefore can appropriately generate the compensation value.

In the above-mentioned Patent Document 1, even when the frequency of the pulsation is small and the pulsation can be suppressed only by the current control unit at low speed, the voltage command correction value is superimposed on the basic value of the voltage command, and if the gain setting is not appropriate, there is a risk that the voltage command correction value will become a disturbance. However, in the above-mentioned motor drive control system S, motor drive control device, and motor drive control method, when neither 2πf _mag > ω _cfi nor 2πf _cog > ω _cfi is satisfied (No) in the process S4, the process S5 is executed and the gains K _TI and K _IV of the first and second variable amplifiers VA1 and VA2 are controlled to 0, so that the compensation value is not generated and the disturbance is prevented.

In the above embodiment, since the motor M is a surface permanent magnet synchronous motor (SPMSM), a compensation value is introduced only to the q-axis that contributes to the torque to cancel out the pulsating torque as necessary. However, compensation values for canceling out the pulsating torque may be introduced to the q-axis and d-axis depending on the type of motor M.

In the above embodiment, it is preferable that the compensation value generating unit CV does not generate the compensation value when the voltage value corresponding to the control command value based on the compensation value exceeds a predetermined output voltage value of the power source supplying power to the motor. The predetermined output voltage value is set appropriately in advance, for example, taking into consideration the specifications and operating conditions of the motor M and inverter IV connected to the power source. Such an electric motor drive control system S, electric motor drive control device, and electric motor drive control method control the electric motor M within the rated voltage value of the power source, thereby avoiding instability of control. In particular, in the above-mentioned Patent Document 1, as described above, the superimposed voltage command is input directly to the PWM control unit without feedback control, so that when the voltage value corresponding to the superimposed voltage command exceeds the power source voltage, control becomes difficult, but this modified embodiment can avoid such a situation.

Figure 6 is a flowchart showing the operation of the electric motor drive control system in the modified form. As shown in Figure 6, the electric motor drive control system in this modified form executes step S11 before executing step S8 described above with reference to Figure 5. That is, the electric motor drive control system in the modified form executes each of steps S1 to S7 described above with reference to Figure 5, and if the result of the determination in step S6 is at least one of the above cases (Yes), the electric motor drive control system S then executes step S11.

In this process S11, the motor drive control system S judges whether the voltage values _vd ^* , _vq ^* corresponding to the control command value based on the compensation value exceed the rated voltage value Vdc of the power source supplying power to the motor M by the gain control unit GC of the compensation value generation unit CV. More specifically, the gain control unit GC judges whether the voltage values _vd ^* , _vq ^* corresponding to the control command value based on the compensation value are a times or less than the rated voltage value Vdc considering the margin a (√( _vd ^* + _vq ^* ) ≦ a × Vdc). a is appropriately set in advance to be less than 1, for example, set to any value in the range of 0.9 < a < 1. If the result of this judgment is that the _vd ^* , _vq ^* are a × Vdc or less (Yes), the motor drive control system S then executes the process S8 described above using FIG. 5, and then ends this process at the current control timing. On the other hand, if the result of the judgment is that _vd ^* , _vq ^* are not equal to or less than a×Vdc (No), the motor drive control system S does not execute anything and ends the process at the current control timing, thereby avoiding instability of the control.

In order to express the present invention, the present invention has been described above adequately and sufficiently through the embodiments with reference to the drawings. However, it should be recognized that a person skilled in the art can easily modify and/or improve the above-mentioned embodiments. Therefore, unless the modification or improvement implemented by a person skilled in the art is at a level that deviates from the scope of the claims described in the claims, the modification or improvement is interpreted as being included in the scope of the claims.

S Motor drive control system M Motor IV Inverter circuit PM PWM modulator DC Drive control unit CS Current measurement unit VS Rotation angle measurement unit CV1 Two-phase to three-phase conversion unit CV2 Three-phase to two-phase conversion unit RSC Rotation speed processing unit PT Pulsating torque estimation unit DA Rotation angle estimation unit PN First pulsating torque estimation unit TC Second pulsating torque estimation unit SM Addition unit CV Compensation value generation unit VA1 First variable amplification unit VA2 Second variable amplification unit GC Gain control unit SB3 First subtraction unit SB4 Second subtraction unit

Claims (4)

An electric motor drive control device for controlling an electric motor,
a pulsation torque estimating unit that estimates a pulsation torque that will occur at the next control timing by using a pulsation model that represents a pulsation torque whose magnitude increases and decreases over time;
a compensation value generating unit that generates a compensation value for canceling the pulsating torque estimated by the pulsating torque estimating unit;
a drive control unit that controls and drives the electric motor with a control command value based on the compensation value generated by the compensation value generation unit,
the pulsating torque includes at least one of a first pulsating torque caused by a spatial high-frequency component of a magnetomotive force distribution in a circumferential direction of the motor and a second pulsating torque which is a cogging torque,
the drive control unit includes a current control system for controlling a drive current of the electric motor and a speed control system for controlling a speed of the electric motor;
the compensation value generating unit generates the compensation value when at least one of a first frequency band that is equal to or lower than a first frequency threshold that is a first cutoff frequency in a first frequency characteristic of the current control system and a second frequency band that is equal to or lower than a second frequency threshold that is a second cutoff frequency in a second frequency characteristic of the speed control system.
Electric motor drive control device. the compensation value generating unit does not generate the compensation value when a voltage value corresponding to a control command value based on the compensation value exceeds a predetermined output voltage value of a power source that supplies power to the electric motor.
The electric motor drive control device according to claim 1. A method for controlling an electric motor, comprising:
a pulsation torque estimating step of estimating a pulsation torque that will occur at the next control timing by using a pulsation model that represents a pulsation torque whose magnitude increases and decreases over time;
a compensation value processing step of determining a compensation value for canceling the pulsating torque estimated in the pulsating torque estimation step;
a drive control step of controlling and driving the electric motor with a control command value based on the compensation value obtained in the compensation value processing step,
the pulsating torque includes at least one of a first pulsating torque caused by a spatial high-frequency component of a magnetomotive force distribution in a circumferential direction of the motor and a second pulsating torque which is a cogging torque,
The compensation value processing step generates the compensation value when at least one of the following occurs: the frequency of the pulsating torque exceeds a first frequency band that is equal to or lower than a first frequency threshold value that is preset based on a first cut - off frequency in a first frequency characteristic of a current control system that controls a drive current of the motor; and the frequency of the pulsating torque exceeds a second frequency band that is equal to or lower than a second frequency threshold value that is preset based on a second cut-off frequency in a second frequency characteristic of a speed control system that controls a speed of the motor.
A method for controlling the drive of an electric motor. An electric motor;
An electric motor drive control unit that controls the electric motor,
The electric motor drive control unit is the electric motor drive control device according to claim 1 or 2.
Electric motor drive control system.