JP7412106B2 - Motor control device and motor control method - Google Patents

Description

The present invention relates to a motor control device and a motor control method.

Patent Document 1 below discloses that in order to cancel torque ripples generated by harmonic components of the induced voltage of a motor, a correction amount including the harmonic content of the harmonic components is calculated, and using the calculated correction amount, A motor control device that corrects a voltage command value for controlling a motor is disclosed.

Patent No. 5574790

The harmonic content rate described in Patent Document 1 is set as a constant. However, the harmonic components included in the induced voltage are not constant with respect to the magnitude (phase current value) of the phase current flowing through the motor, but may change with respect to the value of the phase current flowing through the motor. Therefore, when the harmonic content rate is set as a constant, there is a problem that the torque ripple may not be sufficiently reduced.

The present invention has been made in view of these circumstances, and its purpose is to reduce torque ripple even when the phase current value changes.

One aspect of the present invention is a motor control device that controls a phase current flowing through a motor, the feedback control device generating a command value for driving the motor so that a value of the phase current flowing through the motor becomes a target value. and a correction amount including a harmonic content rate, which is a content rate of the harmonic component with respect to the induced voltage, so as to reduce pulsation occurring in the phase current due to a harmonic component of the induced voltage of the motor. an induced voltage compensator that corrects the command value; and a drive control unit that controls driving of the motor based on the command value corrected by the induced voltage compensator, and the induced voltage compensator The motor control device is characterized in that the harmonic content rate is changed according to the target value.

In the above configuration, the induced voltage compensator includes a storage unit storing correlation information indicating a correlation between the phase current value and the harmonic content rate, and a storage unit that stores the harmonic content based on the target value and the correlation information. The image forming apparatus may further include a correction amount calculation unit that calculates a wave content rate and calculates a correction amount based on the calculated harmonic content rate.

In the above configuration, the correlation information is an information map in which a plurality of current values and the harmonic content rate when the current values flow to the motor as phase currents are associated for each current value, The correction amount calculation unit may calculate the harmonic content rate corresponding to the current value indicated by the target value from the information map, and calculate the correction amount based on the calculated harmonic content rate.

In the above configuration, the motor may be an electric motor for an electric power steering device.

One aspect of the present invention is a motor control method for a motor control device that controls a phase current flowing through a motor, the command value for driving the motor so that the value of the phase current flowing through the motor becomes a target value. and a correction including a harmonic content rate, which is a ratio of the harmonic component to the induced voltage, so as to reduce pulsations occurring in the phase current due to the harmonic component of the induced voltage of the motor. a second step of correcting the command value based on the amount, and a third step of controlling the drive of the motor based on the command value corrected by the induced voltage compensator, is a motor control method characterized in that the step includes a fourth step of changing the harmonic content rate according to the target value.

As described above, according to the present invention, torque ripple can be reduced even when the phase current value changes.

1 is a schematic configuration of an electric power steering device 1 including a motor control device according to the present embodiment. FIG. 3 is a diagram illustrating functional units of an induced voltage compensator 13 according to the present embodiment. It is a figure explaining the relationship between harmonic content rate h and phase current concerning this embodiment. It is a figure explaining the harmonic content rate determination map concerning this embodiment. It is a figure explaining the flow of operation of motor control device 5 concerning this embodiment.

Hereinafter, a motor control device 5 and a motor control method according to the present embodiment will be explained using the drawings.

FIG. 1 is a diagram showing an example of a schematic configuration of an electric power steering device 1 including a motor control device according to the present embodiment.

The electric power steering device 1 is mounted on a vehicle. An electric power steering device 1 detects the steering torque applied to a steering wheel by a driver or the like using a torque sensor 2, and generates a steering assist force corresponding to the detected steering torque using a motor 3, thereby providing a driver's control. This is a device that assists steering.

As shown in FIG. 1, the electric power steering device 1 includes a torque sensor 2, a motor 3, a rotation angle detection section 4, and a motor control device 5.

The torque sensor 2 is provided on a steering shaft connected to a steering wheel. The torque sensor 2 detects the steering torque F applied to the steering wheel by detecting the steering torque generated on the steering shaft. Then, the torque sensor 2 outputs the detected operating torque F to the motor control device 5.

The rotation of the motor 3 is controlled by a motor control device 5. The motor 3 of this embodiment is an electric motor for an electric power steering device. However, the present invention is not limited thereto, and the motor 3 is not limited to one for an electric power steering device, but may be any electric motor used for a vehicle.
The motor 3 applies a steering assist force corresponding to the steering torque F detected by the torque sensor 2 to the steering shaft by rotating. Thereby, the driver's steering operation is assisted and the labor burden on the driver is reduced. In this embodiment, a case will be described in which the motor 3 is a three-phase (U, V, W) brushless motor.

The motor 3 includes a rotor having permanent magnets, and a stator in which coils Lu, Lv, and Lw corresponding to three phases (U, V, and W) are wound in order in the rotational direction of the rotor. Each of the coils Lu, Lv, and Lw of each phase is connected to the motor control device 5.

The rotation angle detection section 4 is provided in the motor 3. The rotation angle detection unit 4 detects an electrical angle θ indicating the rotational position of the rotor of the motor 3. For example, the rotation angle detection section 4 is a magnetic rotary encoder equipped with a resolver or a Hall IC. The rotation angle detection section 4 outputs the detected electrical angle θ to the motor control device 5.

The motor control device 5 controls the rotation of the motor 3 according to the steering torque F detected by the torque sensor 2. The configuration of the motor control device 5 according to this embodiment will be described below.

The motor control device 5 includes a power supply section 6 , a drive section 7 , a current measurement section 8 , and a control section 9 .

The power supply section 6 can use a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. Moreover, the power supply section 6 can also use an electric double layer capacitor (capacitor) instead of a secondary battery. The power supply unit 6 of this embodiment is a battery provided in the vehicle.
Note that the output voltage of the power supply section 6 is assumed to be the battery voltage VB.

The drive unit 7 is an inverter having a plurality of switching elements SW _UH to SW _WL (SW _UH , SW _UL , SW _VH , SW _VL , SW _WH , SW _WL ). For example, the drive unit 7 is a so-called sine wave inverter. The drive unit 7 converts the direct current from the power supply unit 6 into an alternating current (phase current) and outputs it to the motor 3 by controlling the on and off of the switching element using PWM (Pulse Width Modulation). do. As a result, the motor 3 is driven. In this embodiment, a case will be described in which the six switching elements SW _UH to SW _WL are n-type channel FETs (Field Effective Transistors), but the present invention is not limited to this, and for example, IGBTs (Insulated gate bipolar transistors). , and a BJT (bipolar junction transistor).

Specifically, the switching elements SW _UH and SW _UL connected in series, the switching elements SW _VH and SW _VL connected in series, and the switching elements SW _WH and SW _WL connected in series are the power supply section. It is connected in parallel between the high potential (output) side of 6 and the ground potential.

A drain terminal of the switching element SW _UH is connected to an output terminal of the power supply section 6. A source terminal of the switching element SW _UL is connected to GND (ground). A connection point N1 between the source terminal of the switching element SW _UH and the drain terminal of the switching element SW _UL is connected to one end of the coil Lu.

The drain terminal of the switching element SW _VH is connected to the drain terminal of the switching element SW _UH . A source terminal of the switching element SW _VL is connected to GND (ground). A connection point N2 between the source terminal of the switching element SW _VH and the drain terminal of the switching element SW _VL is connected to one end of the coil Lv.

A drain terminal of the switching element SW _WH is connected to a drain terminal of the switching element SW _UH . A source terminal of the switching element _SWWL is connected to GND (ground). A connection point N3 between the source terminal of the switching element SW _WH and the drain terminal of the switching element SW _WL is connected to one end of the coil Lw.

Furthermore, gate terminals of each of the switching elements SW _UH to SW _WL are connected to the control section 9.

The current measurement unit 8 measures phase currents flowing through each of the U-phase winding Lu, the V-phase winding Lv, and the W-phase winding Lw of the electric motor M. The current measuring unit 8 then outputs a U-phase current value Iu that is the current value of the measured U-phase current, a V-phase current value Iv that is the current value of the V-phase current, and a W-phase current value that is the current value of the W-phase current. Each of Iw is output to the control section 9. In this embodiment, the current measuring section 8 includes a plurality of current sensors 8a to 8c. Current sensor 8a is provided between the source terminal of switching element SW _UL and ground. Current sensor 8b is provided between the source terminal of switching element SW _VL and the ground. The current sensor 8c is provided between the source terminal of the switching element _SWWL and the ground. Note that the current sensors 8a to 8c are not particularly limited as long as they can measure current, and may be, for example, shunt resistors or current transformers. Furthermore, the current measurement section 8 may be provided on a connection line that connects the drive section 7 and the motor 3.

Next, the configuration of the control section 9 according to this embodiment will be explained.

The control unit 9 according to the present embodiment includes a target dq-axis current setting unit 10, a three-phase to two-axis conversion unit 11, a feedback control unit 12, an induced voltage compensation unit 13, a two-axis to three-phase conversion unit 14, and a drive control unit 10. 15.

The target dq-axis current setting unit 10 obtains the steering torque F from the torque sensor 2. Further, the target dq-axis current setting unit 10 obtains the electrical angle θ from the rotation angle detection unit 4. Then, the target dq-axis current setting unit 10 sets a target d-axis current value Id _ref , which is the target value of the d-axis current, and a target value of the q-axis current, according to the acquired steering torque F and the electrical angle θ. A target q-axis current value Iq _ref is set. The target dq-axis current setting section 10 outputs the target d-axis current value Id _ref and the target q-axis current value Iq _ref to the feedback control section 12 . Further, the target dq-axis current setting section 10 outputs the target q-axis current value Iq _ref to the induced voltage compensating section 13.

The three-phase-two-axis conversion unit 11 converts the U-phase current value Iu, V-phase current value Iv, and W-phase current value Iw acquired from the current measurement unit 8 using the electrical angle θ acquired from the rotation angle detection unit 4. , into a d-axis current value Id, which is a d-axis current value, and a q-axis current value Iq, which is a q-axis current value. Note that to convert the U-phase current value Iu, V-phase current value Iv, and W-phase current value Iw to the d-axis current value Id and q-axis current value Iq, for example, the following equations (1) and (2) are used. ) is used.

Id=√(2/3)×(−Iu×cosθ−Iv×cos(θ−2π/3)−Iw×cos(θ−4π/3))…(1)
Iq=√(2/3)×(Iu×sinθ+Iv×sin(θ−2π/3)+Iw×sin(θ−4π/3))…(2)

The three-phase-two-axis conversion unit 11 outputs the converted d-axis current value Id and q-axis current value Iq to the feedback control unit 12.

The feedback control unit 12 performs a PI calculation on the deviation Δd between the target d-axis current value Id _ref acquired from the target dq-axis current setting unit 10 and the d-axis current value Id acquired from the three-phase-two-axis conversion unit 11. By executing the above, a d-axis voltage command value Vd, which is a d-axis voltage for bringing the deviation Δd close to zero, is calculated. In addition, the feedback control unit 12 determines the deviation Δq between the target q-axis current value Iq _ref acquired from the target dq-axis current setting unit 10 and the q-axis current value Iq acquired from the three-phase-two-axis conversion unit 11. By executing the PI calculation, a q-axis voltage command value Vq, which is a q-axis voltage for bringing the deviation Δq close to zero, is calculated. The feedback control unit 12 outputs the calculated d-axis voltage command value Vd and q-axis voltage command value Vq to the induced voltage compensation unit 13.

The induced voltage compensator 13 corrects the d-axis voltage command value Vd and the q-axis voltage command value Vq in order to reduce torque ripples generated by harmonic components of the induced voltage of the motor 3, thereby reducing the induced voltage. Compensate for harmonic components. In the following description, compensating for the harmonic components of the induced voltage by correcting the d-axis voltage command value Vd and the q-axis voltage command value Vq may be referred to as "induced voltage compensation."

Specifically, as shown in FIG. 2, the induced voltage compensation section 13 includes a correction amount calculation section 20, a voltage command value correction section 21, and a storage section 22.

When performing induced voltage compensation, the correction amount calculation unit 20 corrects a correction amount Cd for correcting the d-axis voltage command value Vd (hereinafter referred to as "d-axis correction amount") and the q-axis voltage command value Vq. A correction amount (hereinafter referred to as "q-axis correction amount") Cq for Note that in this embodiment, the following equations (3) and (4) are used to calculate the d-axis correction amount and the q-axis correction amount. Note that the correction amount calculation unit 20 obtains the electrical angle θ from the rotation angle detection unit 4.

Cd=ω・G・(−h5−h7)・sin6θ…(3)
Cq=ω・G・(h1+(h7−h5)・cos6θ)…(4)

Here, ω is the angular velocity, and is calculated by the control unit 9 (for example, the induced voltage compensator 13). G is the velocity electromotive force constant. h1 is the content rate of the first harmonic component with respect to the induced voltage, and is set as "1". h5 is the content rate of the fifth-order harmonic component with respect to the induced voltage (fifth-order harmonic content rate), and is not a fixed value but a variable value that changes according to the target q-axis current value Iq _ref . h7 is the content rate of the seventh harmonic component with respect to the induced voltage (seventh harmonic content rate), and is not a fixed value but a variable value that changes according to the target q-axis current value Iq _ref . Note that when compensating only the fifth-order harmonic component, h7 is set to "0". Furthermore, when compensating for n-th harmonic components other than the 5th and 7th harmonics, the content rate of the n-th harmonic components may be included in equations (3) and (4). Even in that case, the content rate of the n-th harmonic component is a variable value that varies depending on the target q-axis current value Iq _ref , as described above. In this embodiment, a case will be described in which fifth-order and seventh-order harmonic components are compensated for. Furthermore, when the fifth-order harmonic content rate h5 and the seventh-order harmonic content rate h7 are not distinguished from each other, they are simply referred to as "harmonic content rate h."

The correction amount calculation unit 20 calculates the fifth harmonic content rate h5 according to the target q-axis current value Iq _ref . Further, the induced voltage compensator 13 determines the seventh harmonic content h7 according to the target q-axis current value Iq _ref .
More specifically, the correction amount calculation unit 20 calculates the fifth harmonic content rate h5 from the target q-axis current value Iq _ref based on correlation information indicating the correlation between the phase current value and the harmonic content rate h1. . Similarly, the correction amount calculation unit 20 calculates the seventh harmonic content rate h7 from the target q-axis current value Iq _ref based on correlation information indicating the correlation between the phase current value and the harmonic content rate h7.

Here, as shown in FIG. 3, the harmonic content rate h included in the induced voltage of the motor 3 is not constant with respect to the magnitude of the phase current flowing through the motor 3 (phase current value), but is There is a correlation that changes nonlinearly with respect to

Therefore, the harmonic content rate h according to the present embodiment is determined not as a constant but as a variable value that varies according to the above correlation. The above-mentioned correlation is determined in advance through experiments or the like, and the above-mentioned correlation information, which is information on the correlation, is stored in the storage unit 22. However, the d-axis current value Id and q-axis current value Iq, which are the actual currents of the phase current values, contain a 6th-order pulsating component due to the harmonic component of the induced voltage, and the harmonic content rate can be calculated from the actual current. When h is determined, a large error occurs in the harmonic content rate h due to its pulsating component. Therefore, since the control unit 9 performs feedback control so that the phase current value follows the target value, the correction amount calculation unit 20 calculates the target value based on the assumption that the same current of the target value is flowing through the motor 3. The harmonic content rate h with respect to (target q-axis current value Iq _ref ) is determined from the correlation information. In other words, the correlation information is information indicating the correlation between the target value of the phase current value and the harmonic content rate. Thereby, the correction amount calculation unit 20 can eliminate the influence of the sixth-order pulsation component and determine the optimal harmonic content rate h even when the phase current value changes due to feedback control.

After determining the fifth-order harmonic content rate h5 and the seventh-order harmonic content rate h7, the correction amount calculation unit 20 further uses the angular velocity ω and the electrical angle θ to calculate the d-axis from the above equations (3) and (4). Calculate the correction amount and the q-axis correction amount.

The voltage command value correction unit 21 obtains the d-axis correction amount and the q-axis correction amount from the correction amount calculation unit 20. Then, the voltage command value correction unit 21 corrects the d-axis voltage command value Vd by adding the d-axis correction amount Cd to the d-axis voltage command value Vd, as shown in equation (5) below. Further, the induced voltage compensator 13 corrects the q-axis voltage command value Vq by adding the q-axis correction amount Cq to the q-axis voltage command value Vq, as shown in equation (6) shown below.
Note that, hereinafter, the corrected d-axis voltage command value Vd will be referred to as "d-axis voltage command value Vd'" and the corrected q-axis voltage command value Vq will be referred to as "q-axis voltage command value Vq'".

Vd'=Vd+Cd...(5)
Vq'=Vq+Cq...(6)

The voltage command value correction section 21 outputs the corrected d-axis voltage command value Vd' and q-axis voltage command value Vq' to the two-axis-to-three-phase conversion section 14.

The storage unit 22 stores, as correlation information, a harmonic content rate determination map (information map) for determining the harmonic content rate h from the target q-axis current value Iq _ref . In the harmonic content rate determination map, a plurality of current values Ix and a harmonic content rate h when the current value Ix flows to the motor as a phase current are associated for each current value Ix. The current value Ix corresponds to the target q-axis current value Iq _ref . The harmonic content rate determination map may be in a table format or may be in a calculation formula.

The harmonic content rate determination map may be such that the harmonic content rate h changes continuously depending on the target q-axis current value Iq _ref , as shown in FIGS. 4(a) and 4(b). , as shown in FIG. 4(c), the harmonic content rate h may change discontinuously in a stepwise manner depending on the target q-axis current value Iq _ref . The harmonic content determination map may be determined experimentally. Furthermore, a plurality of harmonic content rate determination maps may be provided corresponding to each of a plurality of harmonic content rates h. That is, the storage unit 22 may store a plurality of harmonic content determination maps corresponding to a plurality of harmonic content rates. For example, the storage unit 22 includes a first harmonic content determination map for determining the fifth harmonic content h5 from the target q-axis current value Iq _ref , and a map for determining the fifth harmonic content h5 from the target q-axis current value Iq _ref . A second harmonic content rate determination map for determining the content rate h7 may also be stored.

The two-axis to three-phase conversion unit 14 converts the d-axis voltage command value Vd′ and the q-axis voltage command value Vq′ output from the induced voltage compensation unit 13 using the electrical angle θ obtained from the rotation angle detection unit 4. , UVW phase voltage command value Vu, V phase voltage command value Vv, and W phase voltage command value Vw. Note that the following formula ( Equation (9) is used from 7).

Vu=-Vd'×cosθ+Vq'×sinθ...(7)
Vv=-Vd'×cos(θ-2π/3)+Vq'×sin(θ-2π/3)...(8)
Vw=-Vd'×cos(θ-4π/3)+Vq'×sin(θ-4π/3)...(9)

The two-axis to three-phase conversion unit 14 outputs the converted U-phase voltage command value Vu, V-phase voltage command value Vv, and W-phase voltage command value Vw to the drive control unit 15.

The drive control unit 15 generates PWM signals indicating duty ratios corresponding to the U-phase voltage command value Vu, V-phase voltage command value Vv, and W-phase voltage command value Vw obtained from the two-axis-three-phase conversion unit 14, respectively. do. Then, the drive control unit 15 switches the switching elements SW _UH to SW _WL to the on state or off state based on the generated PWM signal.

Next, the flow of the operation of the motor control device 5 according to this embodiment will be explained using FIG. 5. FIG. 5 is a diagram illustrating the flow of operation of the motor control device 5 according to this embodiment.

Upon acquiring the steering torque F from the torque sensor T (step S101), the control unit 9 sets a target d-axis current value Id _ref and a target q-axis current value Iq _ref according to the acquired operating torque F (step S101). S102).
The control unit 9 converts the U-phase current value Iu, V-phase current value Iv, and W-phase current value Iw measured by the current measurement unit 8 into a d-axis current value Id and a q-axis current value Iq (step S103). Then, the control unit 9 performs a PI calculation on the deviation Δd between the target d-axis current value Id _ref and the d-axis current value Id, thereby determining the d-axis voltage command value Vd for bringing the deviation Δd close to zero. Calculate. Furthermore, the feedback control unit 12 executes a PI calculation on the deviation Δq between the target q-axis current value Iq _ref and the q-axis current value Iq, thereby setting the q-axis voltage command value Vq to bring the deviation Δq close to zero. Calculate (step S104).

Next, the correction amount calculation unit 20 of the control unit 9 calculates the value based on the target q-axis current value Iq _ref of the target value of the q-axis current, which is the current caused by torque, and the correlation information stored in the storage unit 22. Then, the harmonic content rate h is determined (step S105), and the d-axis correction amount Cd and the q-axis correction amount Cq are determined based on the determined harmonic content rate h (step S106). For example, the correction amount calculation unit 20 calculates the harmonic content rate h with respect to the target q-axis current value Iq _ref from the harmonic content rate determination map, and calculates the d-axis correction amount Cd and q based on the calculated harmonic content rate h. Find the axis correction amount Cq. For example, the correction amount calculation unit 20 reads out a harmonic content rate determination map, and calculates the harmonic content rate h by inputting a target q-axis current value Iq _ref to the read harmonic content rate determination map. . Then, the correction amount calculation unit 20 calculates the d-axis correction amount Cd and the q-axis correction amount Cq using the harmonic content rate h.

When the correction amount calculation unit 20 calculates the d-axis correction amount and the q-axis correction amount, the voltage command value correction unit 21 adds the d-axis correction amount Cd to the d-axis voltage command value Vd, and adds the d-axis correction amount Cd to the q-axis voltage command value Vq. By adding the q-axis correction amount Cq, the d-axis voltage command value Vd' and the q-axis voltage command value Vq' are determined (step S107).
After that, the control unit 9 converts the d-axis voltage command value Vd' and the q-axis voltage command value Vq' into a U-phase voltage command value Vu, a V-phase voltage command value Vv, and a W-phase voltage command value Vw. A PWM signal is generated from the U-phase voltage command value Vu, V-phase voltage command value Vv, and W-phase voltage command value Vw (step S108). Then, the control unit 9 controls the rotation of the motor 3 by performing PWM control on the switching elements SW _UH to SW _WL based on the generated PWM signal (step S109). Thereby, the motor control device 5 can assist the driver in steering by generating a steering assist force on the steering wheel.

Next, the effects of this embodiment will be explained.
The induced voltage of the motor 3, which is a 3-phase (U, V, W) brushless motor, includes 5th and 7th harmonic components, and these harmonic components become disturbances that cause the actual current (d This appears as sixth-order pulsation in the axis current value Id and q-axis current value Iq). The sixth-order pulsation of the actual current becomes a disturbance in current feedback control, causing a decrease in step response, a decrease in frequency characteristics, and a decrease in controllability of torque ripple reduction. Therefore, it is necessary to perform induced voltage compensation to reduce the pulsation of the actual current so that the expected current can flow.

Here, considering the case where the motor 3 has one phase, the voltage equation of the motor 3 can be expressed by the following equation (10). Note that e is the induced voltage, L is the inductance of the motor 3, V is the voltage applied to the motor 3, R is the resistance of the windings of the motor 3, and I is the phase current value.

Ve-e = I(Ls + R)
I = V-e/(Ls+R)...(10)

Assuming a steady state, the denominator (Ls+R) shown in equation (10) is constant. Therefore, phase current I is proportional to the difference between applied voltage V and induced voltage e. Therefore, when V is a sine wave and e is a sine wave including harmonics, harmonic components of e will appear in the phase current I. Therefore, if the same amount of harmonic components as e are superimposed on V in advance (induced voltage compensation), no harmonic components will appear in the phase current I.
However, the harmonic component included in the induced voltage of the motor 3 is not a constant value with respect to the phase current, but may change nonlinearly with respect to the phase current value. Therefore, if the harmonic content rate is constant, the amount of correction to be superimposed may be insufficient or too large, causing so-called overcompensation or undercompensation.

Therefore, the motor control device 5 according to the present embodiment appropriately changes the harmonic content rate used to calculate the correction amount with respect to the phase current value. However, for this phase current value, the target q-axis current value Iq _ref is used instead of the actual current (q-axis current value Iq). This is because the actual current includes the above-mentioned pulsations. Thereby, the motor control device 5 can suppress overcompensation and undercompensation even if the current value of the phase current flowing through the motor 3 changes, and can maintain the effect of reducing the pulsation of the actual current. As a result, the motor control device 5 can reduce torque ripple.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the range described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the embodiments described above. It is clear from the claims that such modifications or improvements may be included within the technical scope of the present invention.

For example, the correction amount calculation unit 20 of the above embodiment may adjust the electrical angle θ to be substituted into the above equations (3) and (4) when calculating the d-axis correction amount and the q-axis correction amount. Specifically, when calculating the d-axis correction amount and the q-axis correction amount, the correction amount calculation unit 20 determines whether the electrical angle θ substituted into the above formulas (3) and (4) matches the actual electrical angle θr. The value of the electrical angle θ may be changed so as to Thereby, the induced voltage compensator 13 can superimpose the correction amount on the d-axis voltage command value Vd and the q-axis voltage command value Vq with phase errors eliminated, and the torque clip can be further reduced. can.

Note that all or part of the control unit 9 described above may be realized by a computer. In this case, the computer may include a processor such as a CPU or GPU, and a computer-readable recording medium. Then, a program for realizing all or part of the functions of the control section 9 by a computer is recorded on the computer-readable recording medium, and the program recorded on the recording medium is read into the processor and executed. This can be achieved by doing so. Here, the term "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. Furthermore, a "computer-readable recording medium" refers to a storage medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include a device that retains a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. Further, the above-mentioned program may be one for realizing a part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already recorded in the computer system. It may also be realized using a programmable logic device such as an FPGA.

1 Electric power steering device 2 Torque sensor 3 Motor 4 Rotation angle detection section 5 Motor control device 6 Power supply section 7 Drive section 8 Current measurement section 9 Control section 12 Feedback control section 13 Induced voltage compensation section 15 Drive control section 20 Correction amount calculation section 21 Voltage command value correction section 22 Storage section

Claims (5)

A motor control device that controls phase current flowing through a motor,
a target current setting unit that sets a target value of a phase current to be passed through the motor;
a feedback control unit that generates a command value for feedback controlling the motor so that a phase current value flowing through the motor follows the target value;
The command value is calculated based on a correction amount including a harmonic content rate, which is a content rate of the harmonic component with respect to the induced voltage, so as to reduce pulsation occurring in the phase current due to a harmonic component of the induced voltage of the motor. an induced voltage compensation section that corrects
a drive control unit that controls driving of the motor based on the command value corrected by the induced voltage compensation unit;
Equipped with
The induced voltage compensator changes the harmonic content according to the target value.
A motor control device characterized by: The induced voltage compensator includes:
a storage unit storing correlation information indicating a correlation between the phase current value and the harmonic content rate;
a correction amount calculation unit that calculates the harmonic content rate based on the target value and the correlation information, and calculates a correction amount based on the calculated harmonic content rate;
Equipped with
The motor control device according to claim 1. The correlation information is an information map in which a plurality of current values and the harmonic content rate when the current values flow to the motor as phase currents are associated for each current value,
The correction amount calculation unit calculates the harmonic content rate corresponding to the current value indicated by the target value from the information map, and calculates the correction amount based on the calculated harmonic content rate.
The motor control device according to claim 2. The motor control device according to any one of claims 1 to 3, wherein the motor is an electric motor for an electric power steering device. A motor control method for a motor control device that controls phase current flowing in a motor, the method comprising:
setting a target value of a phase current to be passed through the motor;
a first step of generating a command value for feedback controlling the motor so that a phase current value flowing through the motor follows the target value;
The command value is set based on a correction amount including a harmonic content rate, which is a ratio of the harmonic component to the induced voltage, so as to reduce pulsation occurring in the phase current due to a harmonic component of the induced voltage of the motor. a second step of correcting;
a third step of controlling the drive of the motor based on the command value corrected in the second step;
including;
A motor control method, wherein the second step includes a fourth step of changing the harmonic content rate according to the target value.

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