JP2023119456A - Method for controlling electric motor, and motor controller - Google Patents

Abstract

To provide a control method of a motor that improves stability of control in a predetermined operation region, and a motor controller.SOLUTION: A method for controlling an electric motor calculates a voltage command value based on a current command value, converts a DC voltage into an AC voltage based on a PWM signal calculated based on the voltage command value to output it to the electric motor. The voltage command value is calculated by multiplying difference between the current command value and a dq axis current value obtained by converting a current flowing through a motor into a dq coordinates axis with a phase angle of a rotor of the electric motor being a reference. A control gain is calculated based on a compensation inductance value obtained by multiplying an inductance value of the electric motor by a compensation gain for adjusting the inductance value. The compensation gain is set to a value of one or less, and is set so as to become smaller as the number of revolutions or torque of the motor becomes larger.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electric motor control method and an electric motor control apparatus.

Patent Literature 1 discloses a motor control device that detects a current value flowing through an armature winding and performs feedback control.

JP 2014-54127 A

However, in Patent Document 1, in response to changes in the inductance value of the armature winding due to factors such as changes in current, control is performed to correct errors in the inductance value through estimation by feedback control. Correction of the inductance value of the child winding may hinder the stability of control depending on the predetermined operating range of the motor (for example, high torque range or high speed range).

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric motor control method and an electric motor control apparatus that improve the stability of control in a predetermined operating range.

A motor control method according to the present invention calculates a voltage command value based on a current command value, converts a DC voltage to an AC voltage based on a PWM signal calculated based on the voltage command value, and outputs the voltage to the motor. is the control method of This control method multiplies the difference between the current command value and the dq-axis current value obtained by converting the current flowing through the motor into a dq-axis current value based on the phase angle of the rotor of the motor, and multiplies the control gain to obtain the voltage command value. A control gain is calculated based on a compensating inductance value obtained by multiplying the inductance value of the motor by a compensating gain for adjusting the inductance value. Then, the compensation gain is set to a value of 1 or less, and is set to decrease as the rotation speed or torque of the electric motor increases.

According to the present invention, current control can be performed while ensuring desired stability in a predetermined operating region where control stability tends to be insufficient, that is, in a high torque region or a high rotation region.

FIG. 1 is a diagram showing an example of a basic configuration of a control device for an electric motor according to a first embodiment. FIG. 2 is a diagram showing the relationship between the number of revolutions of the motor and the d-axis compensation gain in the first embodiment. FIG. 3 is a control flow diagram of the motor control device of the first embodiment. FIG. 4 is a diagram showing an example of the basic configuration of the motor control device of the second embodiment. FIG. 5 is a control flow diagram of the motor control device of the second embodiment. FIG. 6 is a diagram showing the relationship between the torque of the motor and the q-axis compensation gain in the second embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[First embodiment]
FIG. 1 is a diagram showing an example of a basic configuration of a control device for an electric motor according to a first embodiment.

The control device (control method) for the electric motor (motor 18) in the first embodiment controls the motor 18 of the electric vehicle. Electric vehicles include not only electric vehicles driven by the motor 18, but also hybrid vehicles and fuel cell vehicles.

The motor 18 illustrated in FIG. 1 has a stator and a rotor. Here, regarding the rotor of the motor 18, the type is not limited, and rotors such as a permanent magnet rotor, a wound rotor, and a cage rotor can be applied.

The motor control device of the first embodiment includes a current command generator 1, an interference voltage generator 2, an inductance estimator 3, a compensation gain calculator 4, a P controller 5, an I controller 6, an adder/subtractor 7A, an adder 7B, dq axis/UVW phase converter 8, PWM converter 9, inverter 10, voltage sensor 11, current sensor 12A, current sensor 12B, rotor position sensor 13, UVW phase/dq axis converter 14, subtractor 15A, A subtractor 15B and a rotational speed calculator 16 are included.

Further, the electric motor control device of the first embodiment includes a subtractor 15A (subtractor 15B), a P controller 5 (I controller 6), an adder/subtractor 7A (adder 7B), a dq axis/UVW phase converter 8, , PWM conversion unit 9, inverter 10, current sensor 12A (current sensor 12B), UVW phase/dq axis conversion unit 14, subtractor 15A (subtractor 15B). The d-axis voltage command value v _d ^* and the final q-axis voltage command value v _q ^* ) are feedback-controlled.

The torque command value T ^* , the rotation speed N of the motor 18, and the DC voltage _Vdc of the battery 19 (smoothing capacitor) are input to the current command generator 1 . The current command generator 1 creates a table of the d-axis current command value i _d ^* and the q-axis current command value i _q ^* corresponding to the torque command value T ^* , the rotation speed N, the DC voltage V _dc , and the temperature of the motor 18. are provided in advance.

When the torque command value T ^* , the rotation speed N, the DC voltage V _dc , and the temperature of the motor 18 are input, the current command generation unit 1 refers to the table to generate the d-axis current command values _id ^* and q Output the shaft current command value i _q ^* .

The torque command value T ^* , the rotation speed N of the motor 18, and the DC voltage V _dc of the battery 19 (smoothing capacitor) are input to the interference voltage generator 2 . The interference voltage generation unit 2 prepares in advance a table of the d-axis interference voltage v _{d_dcpl} ^* and the q-axis interference voltage v _{q_dcpl} ^* corresponding to the torque command value T ^* , the rotation speed N, the DC voltage V _dc , and the temperature of the motor 18 . I have.

When the torque command value T ^* , the rotation speed N, the DC voltage _Vdc , and the temperature of the motor 18 are input, the interference voltage generator 2 refers to the table to generate the d-axis interference voltage _{vd_dcpl} ^* and the q-axis Output the interference voltage v _{q_dcpl} ^* .

A d-axis current command value i _d ^* and a q-axis current command value i _q ^* are input to the inductance estimation unit 3 . The inductance estimator 3 has in advance a table corresponding to the d-axis current command value i _d ^* and a table corresponding to the q-axis current command value i _q ^* . When the d-axis current command value i _d ^* is input to the inductance estimator 3, the d-axis table is referenced to output the d-axis inductance value L _{d_est} as an estimated value, and the q-axis current command value i _{q is} output. When ^* is input, the q-axis inductance value L _{q_est} , which is an estimated value, is output by referring to the q-axis table.

The inductance estimator 3 can also calculate the d-axis inductance value L _{d — est} and the q-axis inductance value L _{q — est} as true values using the following equation (1).

where ω _c is the cutoff frequency ω _c (known) of current control (vector current control), Φ is the induced voltage constant of the armature winding (known), and R _a is the resistance of the armature (stator) winding (known), v _dp ^* is a P control d-axis voltage command value v _dp ^* (previous value) described later, and v _qp ^* is a P control q-axis voltage command value v _qp ^* (previous value) described later.

Furthermore, the inductance estimator 3 sets the d-axis inductance value L _{d_est} and the q-axis inductance value L _{q_est} to predetermined fixed values regardless of the d-axis current command value i _d ^* and the q-axis current command value i _q ^* . can be set to

A d-axis inductance value L _{d — est} , a q-axis inductance value L _{q — est} , and the number of revolutions N are input to the compensation gain calculator 4 . The compensation gain calculator 4 has in advance a table for calculating the d-axis compensation gain K _ω (see FIG. 2) corresponding to the rotation speed N of the motor 18 .

When the d-axis inductance value L _{d_est} and the q-axis inductance value L _{q_est} are input, the compensation gain calculation unit 4 calculates a d-axis compensation value L _{d_est_comp} (d-axis compensation inductance value) that becomes the d-axis inductance value L _{d_est} after compensation, and the q-axis compensation value L _{q_est_comp} (q-axis compensation inductance value) that becomes the q-axis inductance value L _{q_est} after compensation is calculated as in the following equation (2).

The subtractor 15A calculates a d-axis difference value ( _id ^* _-id ) by subtracting a d-axis current value _id described later from the d-axis current command value _id ^* .

A subtractor 15B calculates a q-axis difference value (i _q ^* −i _q ) by subtracting a q-axis current value i _q described later from the q-axis current command value i _q ^* .

A d-axis difference value ( _id ^* _-id ), a q-axis difference value ( _iq ^* _-iq ), a d-axis compensation value _{Ld_est_comp} , and a q-axis compensation value _{Lq_est_comp} are input to the P control unit 5. be.

Based on the cutoff frequency ω _c , the d-axis compensation value L _{d_est_comp} , and the q-axis compensation value L _{q_est_comp} , the P control unit 5 calculates the d-axis proportional gain K _dp (control gain) and q Calculate the axis proportional gain K _qp (control gain).

Further, the P control unit 5 calculates a P control d-axis voltage command value v _dp ^* based on the d-axis difference value (i _d ^* -i _d ) and the d-axis proportional gain K _dp as shown in the following equation (4). is calculated, and the P control q-axis voltage command value _vqp ^* is calculated based on the q-axis difference value ( _iq ^* _-iq ) and the q-axis proportional gain _Kqp .

The d-axis difference value (i _d ^* -i _d ) and the q-axis difference value (i _q ^* -i _q ) are input to the I control unit 6 .

Based on the armature (stator) winding resistance R _a and the cutoff frequency ω _c , the I control unit 6 calculates the d-axis integral gain K _di and the q-axis integral gain K di as shown in the following equation (5): Calculate K _qi .

Further, as _shown in _the following equation (6), the I control unit 6 _calculates ^the I control d-axis voltage command value v _di ^* is calculated, and _the I control q-axis voltage command value _vqi ^* is calculated based on the q-axis difference value (iq _* ^-iq ) and the q-axis integral gain _Kqi .

The d-axis integral gain _Kdi may be multiplied by the d-axis compensation gain _Kω , or the q-axis integral gain _Kqi may be multiplied by a q-axis compensation gain _KT described later.

The ^adder / ^subtractor 7A, _as shown in the following equation ( ₇ ), calculates _the ^final d A shaft voltage command value v _d ^* is calculated.

The adder 7B, as _shown in _the ^following equation (8) _, calculates ^{the final} A q-axis voltage command value v _q ^* is calculated.

The final d-axis voltage command value v _d ^* , the final q-axis voltage command value v _q ^* , and the electrical angle θ detected by the rotor position sensor 13 are input to the dq-axis/UVW phase converter 8 .

The dq-axis/UVW-phase converter 8 converts the final d-axis voltage command value v _d ^* and the final q-axis voltage command value v _q ^* into three-phase voltage command values (v _u ^* , _vv ^* , _vw ^* ) and output.

The PWM conversion unit 9 performs dead time compensation and voltage utilization rate improvement processing (both of which are known), and the power element of the inverter 10 corresponding to the three-phase voltage command values (v _u ^* , v _v ^* , v _w ^* ) to generate drive signals (D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu ^* , D _wl ^* ) (PWM signals).

A battery 19 and a smoothing capacitor (not shown) are connected to the inverter 10 . When drive signals (D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu ^* , D _wl ^* ) for the power devices are input to the inverter 10 , the power devices (IGBTs, etc.) are driven and the battery 19 output voltage (DC voltage V _dc ) is converted into pseudo AC voltages (v _u , v _v , v _w ) and output to the motor 18 .

Voltage sensor 11 detects a DC voltage _Vdc of battery 19 .

The current sensor 12A detects, for example, the U-phase current value i _u among the three-phase currents supplied to the motor 18, and the current sensor 12B detects the V-phase current value _iv . In principle, the W-phase current value _iw that is not detected can be obtained by the following equation (10).

A rotor position sensor 13 detects an electrical angle θ of the rotor of the motor 18 .

The U-phase current value i _u , the V-phase current value _iv , and the electrical angle θ are input to the UVW-phase/dq-axis converter 14 .

The UV W _- phase/dq-axis conversion unit 14 performs the _following ( ₁₁ ), the three-phase current values (i _u , _iv , i _w ) are converted into d-axis current value _id (dq-axis current value) and q-axis current value i _q (dq-axis current value) and output .

The rotational speed calculation unit 16 calculates and outputs the rotational speed N of the motor 18 from the amount of change in the electrical angle θ per time.

FIG. 2 is a diagram showing the relationship (table) between the rotational speed N of the motor 18 and the d-axis compensation gain _Kω of the first embodiment. As shown in FIG. 2, the compensation value indicated by the d-axis compensation gain Kω is 1 when the absolute value of the rotation speed N is from zero to the predetermined rotation speed N1. It draws a monotonically decreasing curve as it increases.

Here, the predetermined number of revolutions N1 is set based on the current control cycle of the electric motor control device of the present embodiment. It corresponds to the number of rotations N when substantially matching the dead time (control delay time) of the control loop to be calculated. Here, the dead time is, for example, the time from when the voltage command value is output to when the voltage command value starts to be reflected in the output of the motor 18 (d-axis current, q-axis current). In any case, FIG. 2 shows a case where the compensation amount is set so as to secure a certain value or more of stability (phase margin), and the compensation value changes depending on the control design criteria.

By the way, regarding the frequency characteristics (Bode diagram) of the gain and phase of the control loop, the gain characteristic curve showing the relationship between gain and frequency monotonically decreases as the frequency increases, but the peak frequency (for example, 1000 [ Hz]), reaches a maximum value at the peak frequency, and monotonously decreases again as the frequency becomes higher than the peak frequency. At this time, the gain becomes a value higher than 0 [dB] at the peak value.

In addition, the phase characteristic curve that shows the relationship between phase and frequency has a maximum phase (for example, around 15 [deg]) at a frequency lower than the peak frequency (for example, 600 [Hz]), but decreases sharply when the frequency is exceeded. and reaches −180 [deg] at the inversion frequency (eg, 1500 [Hz]).

Then, when the peak frequency is close to the control frequency of the control loop (especially the frequency corresponding to dead time), the rotation speed N of the motor 18 converges to a predetermined rotation speed N1 (for example, 10000 [rpm]) by the peak frequency. The proximity reduces the stability of motor control. As for the phase margin, the required phase margin (for example, 40 [deg]) can be secured when the rotation speed N is lower than the peak frequency equivalent, but when the rotation speed N exceeds the predetermined rotation speed N1, the required phase margin It becomes difficult to secure

Therefore, in this embodiment, as shown in FIG. 2, the q-axis compensation gain _KT is set to 1 when the rotation speed N of the motor 18 is equal to or lower than the predetermined rotation speed N1, and when the rotation speed N exceeds the predetermined rotation speed N1, the q-axis compensation gain KT is set to 1. It is set to monotonically decrease as it increases. Further, the d-axis compensation value _{Ld_est_comp} is calculated as shown in equation (2). As a result, the gain characteristic curve shifts to a lower gain as a whole. Therefore, the gain crossover frequency of 0 [dB], which is higher than the peak frequency of the gain characteristic curve, shifts to the low frequency side.

On the other hand, the phase characteristic curve does not change even if the d-axis compensation value L _{d_est_comp} is calculated as in equation (2). Further, as described above, the phase characteristic curve monotonically decreases from a predetermined frequency lower than the peak frequency as the starting point to higher frequencies. Therefore, the phase margin in the phase characteristic curve can be increased more than when the d-axis inductance is set to the d-axis inductance value _{Ld_est} .

In particular, motor control can be executed more stably by setting the d-axis compensation gain _Kω to a low value so that the gain at the peak frequency is lower than 0 [dB] in the gain characteristic curve.

In a coordinate space in which the horizontal axis is the d-axis inductance and the vertical axis is the phase margin, when a characteristic curve representing the relationship between the d-axis inductance and the phase margin is shown, the phase margin increases monotonically as the d-axis inductance decreases. becomes a curve. On the other hand, when the rotational speed N is increased, the characteristic curve shifts in the direction of decreasing the phase margin. Consider, for example, a case in which a straight line is drawn so that the phase margin has a desired constant value (for example, 40 [dB]) in the coordinate space. In this case, even if the rotation speed N changes _, the d-axis inductance at which the characteristic curve intersects the straight line can be selected. It is sufficient to set the curve shape of the above area.

[Control flow]
FIG. 3 is a control flow diagram of the motor control device of the first embodiment. In step S101, the inductance estimator 3 refers to the table, estimates the d-axis inductance value _{Ld_est} based on the d-axis current command value _id ^* , and calculates the q-axis inductance value based on _{the q} -axis current command value iq ^* . Estimate the value L _{q_est} .

In step S102, the compensation gain calculator 4 refers to the table and calculates the d-axis compensation gain _Kω for the d-axis inductance based on the rotation speed N.

In step S103, the compensation gain calculator 4 calculates the q-axis compensation value L _{q_est_comp} from the q-axis inductance value L _{q_est} based on Equation (2), and calculates the d-axis inductance value L based on the d-axis compensation gain _Kω . A d-axis compensation value L _{d_est_comp} is calculated from _{d_est} .

In step S104, the P control unit 5 calculates the d-axis proportional gain K _dp and calculates the P control d-axis voltage command value v _dp ^* based on the above equation (4). The P control unit 5 also calculates the q-axis proportional gain K _qp and calculates the P control q-axis voltage command value v _qp ^* based on the equation (4).

In step S105, the I control unit 6 calculates the d-axis integral gain K _di and calculates the I control d-axis voltage command value v _di ^* based on the above equation (6). The I control unit 6 also calculates the q-axis integral gain _Kqi , and calculates the I-control q-axis voltage command value _vqi ^* based on the equation (6).

In step S106, the adder/subtractor 7A converts the P control d-axis voltage command value _vdp ^* , the I control d-axis voltage command value _vdi ^* , and the d-axis interference voltage _{vd_dcpl} ^* into Based on this, the final d-axis voltage command value v _d ^* is calculated. Similarly, the adder 7B adds the P control q-axis voltage command value _vqp ^* , the I control q-axis voltage command value _vqi ^* , and the q-axis interference voltage _{vq_dcpl} ^* to Based on this, the final q-axis voltage command value v _q ^* is calculated.

In step S107, the dq-axis/UVW-phase converter 8 converts the final d-axis voltage command value v _d ^* and the final q-axis voltage command value v _q ^* to the pseudo three-phase AC voltage (v _u , v _v , v _w ).

In step S108, the PWM converter 9 converts the three-phase voltage command values (v _u ^* , v _v ^* , v _w ^* ) into drive signals (D _uu ^* , D _ul ^* , D _vu ^* , _Dvl ^* , _Dwu ^* , _Dwl ^* ).

[Second embodiment]
FIG. 4 is a diagram showing an example of the basic configuration of the motor control device of the second embodiment. FIG. 5 is a control flow diagram of the motor control device of the second embodiment.

The electric motor control apparatus of the second embodiment includes an estimated torque calculator 17 that estimates the torque T applied to the motor 18, and the compensation gain calculator 4 _calculates the q-axis compensation value L _{q_est_comp} based on the torque estimated value Test. Calculate

The control flow of the second embodiment is similar to that of the first embodiment in steps S101 and steps S104 to S108, but as shown in FIG. Move to S104.

In step S102A, when the d-axis current value _id and the _q -axis current value iq output from the UVW-axis/dq-axis conversion unit 14 are input, the estimated torque calculation unit 17 refers to a table prepared in advance. Output the torque estimate T _est .

In step S103A, the d-axis inductance value _{Ld_est} , the q-axis inductance value _{Lq_est} , and the torque estimated value _{Test are} input to the compensation gain calculator 4. FIG. The compensation gain calculator 4 has in advance a table for calculating the q-axis compensation gain K _T (see FIG. 6) corresponding to the estimated torque value T _est .

Then, when the d-axis inductance value L _{d_est} and the q-axis inductance value L _{q_est} are input, the compensation gain calculation unit 4 calculates the d-axis compensation value L _{d_est_comp} and the q-axis compensation value L _{q_est_comp} according to the following equation (12). Calculate as follows.

Components other than the above are the same as in the first embodiment.

FIG. 6 is a diagram showing the relationship between the torque T of the motor 18 and the q-axis compensation gain _KT according to the second embodiment. With respect to the gain and phase frequency characteristics (bode plots) of the control loop described above, changes in the torque T applied to the motor 18 do not change the phase characteristic curve. On the other hand, the gain characteristic curve shifts in the direction in which the gain increases as the torque T increases. Therefore, the gain margin is reduced at the frequency where the phase is -180 [deg].

Therefore, in this embodiment, as shown in FIG. 6, the q-axis compensation gain _KT is set to decrease as the torque T increases. As a result, even if the torque T changes, a decrease in the gain margin can be suppressed. For example, even if the torque T changes, the gain margin can be kept constant (for example, 12 [dB]).

In a coordinate space where the horizontal axis is the q-axis inductance and the vertical axis is the gain margin, the characteristic curve representing the relationship between the q-axis inductance and the gain margin monotonically increases as the q-axis inductance decreases. It becomes a curve to On the other hand, when the torque T is increased, the characteristic curve shifts in the direction of decreasing the gain margin. Consider, for example, a case in which a straight line is drawn in which the gain margin is a desired constant value (for example, 12 [dB]) in the coordinate space. In this case, if the curve shape of the q-axis compensation gain _KT shown in FIG. good.

[Effect of this embodiment]
According to the control method ^of the electric motor (motor ¹⁸ ) _of the present embodiment _, the voltage command value (P control d-axis voltage Command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) is calculated, and based on the voltage command values (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) Based on the calculated PWM signals (driving signals (D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu ^* , D _wl ^* )), the DC voltage V _dc is changed to an AC voltage (pseudo three-phase AC voltage). (v _u , v _v , v _w )) and output to the electric motor (motor 18), wherein the current command value (d-axis current command value _id ^* , q-axis current command value i _q ^* ) and a dq-axis current value (d-axis current value _id , q-axis current value i _q ) and the difference between them is multiplied by the control gain (d-axis proportional gain K _dp , q-axis proportional gain K _qp ) to obtain a voltage command value (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) is calculated, and the control gains (d-axis proportional gain K _dp , q-axis proportional gain K _qp ) are calculated using the inductance value of the electric motor (motor 18) (d-axis inductance value L _{d_est} , The q-axis inductance value L _{q_est} ) is multiplied by compensation gains (d-axis compensation gain K _ω , q-axis compensation gain K _T ) for adjusting the relevant inductance values (d-axis inductance value L _{d_est} , q-axis inductance value L _{q_est} ). calculated based on the compensation inductance values (d-axis compensation value _{L d_est_comp} , q _- axis compensation value L _{q_est_comp} ) obtained by , and is set to decrease as the rotational speed N or torque T of the electric motor (motor 18) increases.

According to the above method, current control can be performed while ensuring desired stability in a predetermined operating region where control stability tends to be insufficient, that is, in a high torque region or a high revolution region.

In the present embodiment, the current command values (d-axis current command value i _d ^* , q-axis current command value i _q ^* ) include the q-axis current command value i _q ^* , which is the q-axis component of the dq coordinate axes, The dq-axis current values (d-axis current value i _d , q-axis current value i _q ) include the q-axis current value i _q that is the q-axis component, and the voltage command values (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) includes a q-axis voltage command value (P control q-axis voltage command value v _qp ^* ) that is a q-axis component, and an inductance value (d-axis inductance value L _{d_est} , q-axis The inductance value L _{q_est} ) includes the q-axis inductance value L _{q_est} , the compensation gains (d-axis compensation gain K _ω , q-axis compensation gain K _T ) include the q-axis compensation gain K _T and the compensation inductance value (d-axis The compensation value L _{d_est_comp} , q-axis compensation value L _{q_est_comp} ) includes the q-axis compensation inductance value (q-axis compensation value L _{q_est_comp} ), and the control gains (d-axis proportional gain K _dp , q-axis proportional gain K _qp ) are q Includes the q-axis control gain (q-axis proportional gain _{K qp )} calculated based on the q-axis compensation inductance value (q-axis compensation value L _{q_est_comp} ) obtained by multiplying the axis inductance value L _{q_est} by the q-axis compensation gain KT. , the q-axis voltage command value (P control q-axis voltage command value v _qp ^* ) is calculated by dividing the difference between the q-axis current command value i _q ^* and the q-axis current value i _q by the q-axis control gain (q-axis proportional gain K _qp ), the q-axis compensation gain _KT is set to a value of 1 or less, and is set to decrease as the torque T increases.

By setting the q-axis inductance to decrease as the torque T increases by the above method, the gain in the frequency band where the phase reaches -180 [deg] in the Bode diagram is reduced, and the desired gain margin is achieved. can be secured.

In the present embodiment, the current command values (d-axis current command value i _d ^* , q-axis current command value i _q ^* ) further include a d-axis current command value i _d ^* , which is a d-axis component of the dq coordinate axes. , the voltage command value (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) is the d-axis component d-axis voltage command value (P control d-axis voltage command value v _dp ^* ), the q-axis inductance value L _{q_est} is calculated based on the d-axis current command value i _d ^* , the q-axis current command value i _q ^* , and the d-axis voltage command value (P control d-axis voltage command value v _dp ^* ) set to a calculated value or a predetermined fixed value.

By the above method, control performance (control accuracy, control stability) in the low torque range can be ensured.

In the present embodiment, the current command values (d-axis current command value i _d ^* , q-axis current command value i _q ^* ) include the d-axis current command value i _d ^* , which is the d-axis component of the dq coordinate axes, The dq-axis current values (d-axis current value i _d , q-axis current value i _q ) include the d-axis current value _{i d} that is the d-axis component, and the voltage command values (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) includes a d-axis voltage command value (P control d-axis voltage command value v _dp ^* ) that is a d-axis component, and an inductance value (d-axis inductance value L _{d_est} , q-axis The inductance value L _{q_est} ) includes the d-axis inductance value L _{d_est} , the compensation gains (d-axis compensation gain K _ω , q-axis compensation gain K _T ) include the d-axis compensation gain K _ω , and the compensation inductance value (d-axis The compensation value L _{d_est_comp} , q-axis compensation value L _{q_est_comp} ) includes the d-axis compensation inductance value (d-axis compensation value L _{d_est_comp} ), and the control gains (d-axis proportional gain K _dp , q-axis proportional gain K _qp ) are d Includes the d-axis control gain (d-axis proportional gain K _{dp )} calculated based on the d-axis compensation inductance value (d-axis compensation value L _{d_est_comp} ) obtained by multiplying the axis inductance value L _{d_est} by the d-axis compensation gain Kω. , the d-axis voltage command value (P control d-axis voltage command value v _dp ^* ) is the difference between the d-axis current command value _id ^* and the d-axis current value _id , and the d-axis control gain (d-axis proportional gain K _dp ), the d-axis compensation gain _Kω is set to a value of 1 or less, and is set to decrease as the number of revolutions N increases.

By setting the d-axis inductance to decrease as the number of revolutions N increases, the peak value of the gain generated on the high frequency side in the Bode diagram is suppressed to 0 [dB] or less. You can secure a margin.

In the present embodiment, the current command values (d-axis current command value _id ^* , _q -axis current command value iq ^* ) further include a q-axis current command value iq ^* , which is the q _- axis component of the dq coordinate axes. , the voltage command value (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) is the q-axis component of the q-axis voltage command value (P control q-axis voltage command value v _qp ^* ), the d-axis inductance value L _{d_est} is calculated based on the d-axis current command value i _d ^* , the q-axis current command value i _q ^* , and the q-axis voltage command value (P control q-axis voltage command value v _qp ^* ). or a predetermined fixed value, the d-axis compensation gain _Kω is set to 1 until the absolute value of the rotation speed N reaches a predetermined rotation speed N1, and when it exceeds the predetermined rotation speed N1 Set to a value lower than 1.

By the above method, control performance (control accuracy and control stability) can be ensured in a region where the rotation speed N is in the low to medium speed range.

In the above method, the predetermined number of revolutions N1 is set so that the electrical angle period (the cycle of the electrical angle θ) of the electric motor (motor 18) corresponding to the predetermined number of revolutions N1 is the voltage command value (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value _vqp ^* ) is set to the number of rotations N of the electric motor (motor 18) when substantially matching the dead time of the control loop for calculating the value vqp*).

According to the above method, the d-axis compensation gain K _ω compensates the d-axis gain (d-axis proportional gain K _dp ) only in the high rotation range where the insufficient phase margin is greatly affected based on the current control cycle in the control loop. Therefore, it is possible to ensure control performance (control accuracy and control stability) in a region where the rotational speed N is in the low to medium speed range.

According to the controller for ^the electric motor (motor 18) _of ^the present embodiment _, the voltage command value (P control d-axis voltage Command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) is calculated, and based on the voltage command values (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) Based on the calculated PWM signals (driving signals (D _uu ^* , D _ul ^* , D _vu ^* , D _vl ^* , D _wu ^* , D _wl ^* )), the DC voltage V _dc is changed to an AC voltage (pseudo three-phase AC voltage). (v _u , v _v , v _w )) and output to the electric motor (motor 18), wherein the current command value (d-axis current command value _id ^* , q-axis Inductance estimation means (inductance estimation unit 3) for estimating the inductance value (d-axis inductance value L _{d_est} , q-axis inductance value L _{q_est} ) of the electric motor (motor 18) based on the current command value i _q ^* ); _Compensation gains ₍ d-axis _{compensation gain K ω ,} q _- axis Compensation gain calculation means (compensation gain calculator 4) for calculating compensation inductance values (d-axis compensation value L _{d_est_comp} , q-axis compensation value L _{q_est_comp} ) by multiplying compensation gain K _T ); compensation inductance value (d-axis compensation _Control ^gain ₍ ^d _{- axis} Proportional gain K _dp , q-axis proportional gain K _qp ) are calculated, and current command values (d-axis current command value _id ^* , q-axis current command value i _q ^* ) and current flowing through the electric motor (motor 18) are calculated. _Control gain ₍ d-axis proportional gain K _dp , q-axis proportional gain K _qp ) to calculate the voltage command value (P control d-axis voltage command value v _dp ^* , P control q-axis voltage command value v _qp ^* ) means (P control unit 5), and compensation gain calculation means (compensation gain calculation unit 4) sets the compensation gains (d-axis compensation gain K _ω , q-axis compensation gain K _T ) to a value of 1 or less. In addition, it is set to decrease as the number of revolutions N or torque T of the electric motor (motor 18) increases.

With the above configuration, current control can be performed while ensuring desired stability in a predetermined operating region where control stability tends to be insufficient, that is, in a high torque region or a high rotation region.

An object of the present invention is to adjust a compensation gain by paying attention to a control signal in a high rotation region or a high torque region. Therefore, the signal used in the compensation gain calculation unit 4 shown in the embodiment is not limited to the rotational speed N and the torque estimated value _Test , but a control signal that changes with the rotational speed N and the torque T other than the above is used. It is also possible to As an alternative to the estimated torque value Test in _FIG . 4, the same effect can be obtained by referring to the q-axis compensation gain _KT based on the actual current value or current command value.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have. Moreover, the above-described embodiments can be combined as appropriate.

3 inductance estimator, 4 compensation gain calculator, 5 P controller, 18 motor

Claims (7)

A motor control method for calculating a voltage command value based on a current command value, converting a DC voltage to an AC voltage based on a PWM signal calculated based on the voltage command value, and outputting the AC voltage to the motor,
The voltage command value obtained by multiplying the difference between the current command value and a dq-axis current value obtained by converting the current flowing in the motor into a dq-axis current value based on the phase angle of the rotor of the motor by a control gain to calculate
calculating the control gain based on a compensation inductance value obtained by multiplying the inductance value of the electric motor by a compensation gain for adjusting the inductance value;
A method of controlling an electric motor, wherein the compensation gain is set to a value of 1 or less and is set to decrease as the rotational speed or torque of the electric motor increases. the current command value includes a q-axis current command value that is a q-axis component of the dq coordinate axes;
the dq-axis current value includes a q-axis current value that is the q-axis component;
The voltage command value includes a q-axis voltage command value that is the q-axis component,
the inductance value includes a q-axis inductance value;
the compensation gain includes a q-axis compensation gain;
the compensating inductance value includes a q-axis compensating inductance value;
The control gain includes a q-axis control gain calculated based on the q-axis compensation inductance value obtained by multiplying the q-axis inductance value by the q-axis compensation gain,
calculating the q-axis voltage command value by multiplying the difference between the q-axis current command value and the q-axis current value by the q-axis control gain;
2. The motor control method according to claim 1, wherein the q-axis compensation gain is set to a value of 1 or less and is set to decrease as the torque increases. the current command value further includes a d-axis current command value that is a d-axis component of the dq coordinate axes;
the voltage command value further includes a d-axis voltage command value that is the d-axis component;
3. The electric motor according to claim 2, wherein the q-axis inductance value is set to a calculated value calculated based on the d-axis current command value, the q-axis current command value, and the d-axis voltage command value, or a predetermined fixed value. control method. the current command value includes a d-axis current command value that is a d-axis component of the dq coordinate axes;
the dq-axis current value includes a d-axis current value that is the d-axis component;
the voltage command value includes a d-axis voltage command value that is the d-axis component;
the inductance value includes a d-axis inductance value;
The compensation gain includes a d-axis compensation gain,
the compensating inductance value includes a d-axis compensating inductance value;
The control gain includes a d-axis control gain calculated based on the d-axis compensation inductance value obtained by multiplying the d-axis inductance value by the d-axis compensation gain,
calculating the d-axis voltage command value by multiplying the difference between the d-axis current command value and the d-axis current value by the d-axis control gain;
2. The motor control method according to claim 1, wherein the d-axis compensation gain is set to a value of 1 or less and is set to decrease as the rotation speed increases. the current command value further includes a q-axis current command value that is a q-axis component of the dq coordinate axes;
the voltage command value further includes a q-axis voltage command value that is the q-axis component;
setting the d-axis inductance value to a calculated value calculated based on the d-axis current command value, the q-axis current command value, the q-axis voltage command value, or a predetermined fixed value;
5. The electric motor control method according to claim 4, wherein the d-axis compensation gain is set to 1 until the absolute value of the rotational speed reaches a predetermined rotational speed, and is set to a value lower than 1 when the absolute value of the rotational speed exceeds the predetermined rotational speed. . 6. The predetermined number of rotations is set to the number of rotations of the electric motor when the electrical angle period of the electric motor corresponding to the predetermined number of rotations substantially coincides with dead time of a control loop for calculating the voltage command value. A method of controlling the described electric motor. A motor control device that calculates a voltage command value based on a current command value, converts a DC voltage to an AC voltage based on a PWM signal calculated based on the voltage command value, and outputs the AC voltage to the motor,
inductance estimation means for estimating an inductance value of the electric motor based on the current command value;
Compensation gain calculation means for calculating a compensation inductance value by multiplying the inductance value by a compensation gain for adjusting the inductance value;
A control gain for calculating the voltage command value is calculated based on the compensating inductance value, and the current command value and the current flowing in the motor are plotted on a dq coordinate axis based on the phase angle of the rotor of the motor. voltage command value generating means for calculating the voltage command value by multiplying the difference between the dq-axis current value obtained by the conversion and the control gain,
The compensation gain calculation means is
A control device for an electric motor, which sets the compensation gain to a value of 1 or less and is set to decrease as the rotational speed or torque of the electric motor increases.