JP2009189146A - Control unit for electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control unit for an electric motor capable of sufficiently taking measures for torque oscillations and out-of-synchronization and widely ensuring an operable area in using an embedded-magnet type motor as a synchronous motor. <P>SOLUTION: The control unit includes: a target DQ-axes current command value calculation part 11 for specifying a Q-axis current target value and a D-axis current target value; a three-phase current detection part 19 for detecting AC current; a rotation angle detection part 20 for detecting a rotation angle; a current conversion part 18 for calculating the detected value of Q-axis current and the detected value of D-axis current; a Q-axis current FB controller 14 for calculating a Q-axis current command value; a D-axis current FB controller 15 for calculating a D-axis current command value; an inverter control signal calculation part 16 for calculating a control signal of an inverter; and a motor torque estimation part 17 for estimating motor torque. The Q-axis current FB controller 14 and the D-axis current FB controller 15 perform gain processing for reducing P gain and I gain in PI control as shown in Fig. 2 when the motor torque is greater than a predetermined value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention belongs to the technical field of electric motor control devices.

Conventionally, the speed controller outputs a torque current command so that the speed command value and the rotational speed of the synchronous motor coincide with each other, and is configured by a proportional-integral control system. The γ-axis current and δ-axis current controller are: Proportional integral control method that outputs γ-axis current command value and γ-axis current detection value, and δ-axis voltage command value and γ-axis voltage command value so that torque current command value and δ-axis current detection value match each other (For example, refer to Patent Document 1).
JP 2006-87263 A (page 2-12, all figures)

  However, conventionally, when an embedded magnet type is used as a synchronous motor (synchronous motor), it has been difficult to sufficiently ensure a countermeasure against torque vibration, a step-out countermeasure, and a wide range of an operable region.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to prevent torque vibration, step-out, and operation range when using an embedded magnet type as a synchronous motor (synchronous motor). An object of the present invention is to provide an electric motor control device that can sufficiently ensure a wide area.

  To achieve the above object, according to the present invention, a target DQ-axis current command value calculating means for setting a target Q-axis current and a target D-axis current of the three-phase AC synchronous motor based on a request to the three-phase AC synchronous motor. A three-phase current detecting means for detecting an alternating current flowing in each phase, a rotation angle detecting means for detecting a rotation angle of the three-phase AC synchronous motor, and the rotation angle with respect to the alternating current of each phase. Current conversion means for performing Clark conversion and Park conversion to calculate actual Q-axis current and actual D-axis current, and Q-axis by PI control so that the difference between the target Q-axis current and actual Q-axis current is reduced. Q-axis command value calculating means for calculating a voltage command value, and D-axis command value calculating means for calculating a D-axis voltage command value by PI control so that a difference between the target D-axis current and the actual D-axis current is reduced. And the Q-axis voltage command value and the From the shaft voltage command value and the rotation angle, an inverter control signal calculation means for calculating a control signal of a switching element of an inverter that drives the three-phase AC synchronous motor, and a motor torque generated by the three-phase AC synchronous motor are estimated. A motor torque estimating means, wherein the Q-axis command value calculating means and the D-axis command value calculating means are compared with a case where the motor torque is smaller than a predetermined value when the motor torque is larger than a predetermined value. And gain changing means for reducing P gain and I gain of PI control.

  Therefore, in the present invention, when the embedded magnet type is used as the synchronous motor (synchronous motor), it is possible to sufficiently ensure the torque vibration countermeasure, the step-out countermeasure, and the wide area of the operable region.

  Embodiments for realizing the control device for an electric motor according to the present invention will be described in the first embodiment corresponding to the invention according to claims 1, 3, 4, 5, and 7, and the claims 1, 3, 4, and 5. A second embodiment corresponding to the present invention and a third embodiment corresponding to the first, second, fourth, and fifth aspects of the invention will be described.

First, the configuration will be described.
FIG. 1 is a diagram illustrating a block configuration of an electric motor control apparatus according to the first embodiment.
Examples of the electric motor control device according to the first embodiment include an electric compressor control device in a vehicle air conditioner and an EV or HEV drive motor control device.
The electric motor control device 1 according to the first embodiment is provided as a part of a controller of a three-phase synchronous electric motor. Therefore, the target speed of the three-phase synchronous electric motor is set by the other part of the controller and is input to the electric motor control device 1. And the electric motor control apparatus 1 outputs a control signal to the motor inverter 2 which consists of an inverter and a three-phase synchronous electric motor.

The electric motor control device 1 includes a target DQ axis current command value calculation unit 11, an adder 12, an adder 13, a Q axis current FB controller 14, a D axis current FB controller 15, an inverter control signal calculation unit 16, a motor torque. An estimation unit 17, a current conversion unit 18, a three-phase current detection unit 19, a rotation angle detection unit 20, and a rotation speed detection unit 21 are provided.
The target DQ axis current command value calculation unit 11 includes an adder 111, a speed FB controller 112, and a DQ axis current distribution unit 113, and calculates a target value of the DQ axis current command value.

Adder 111 calculates the deviation between the target rotational speed of the three-phase synchronous electric motor and the actual value of the detected rotational speed.
The speed FB controller 112 performs a feedback calculation that multiplies the deviation of the speed by a feedback gain, for example, a PI control calculation, and calculates a DQ axis current command value Ia.
The DQ-axis current distribution unit 113 distributes the current from the DQ-axis current command value Ia to the D-axis current target value Id ^* and the Q-axis current target value Iq ^* and outputs it.
For example, distribution is performed according to the following formula. Here, 20 degrees corresponds to an advance angle, and is a value determined from motor device constants.
(Equation 1)

Id ^* = sin (20/180 ・ π) ・ Ia
(Equation 2)

Iq ^* = cos (20/180 ・ π) ・ Ia

The adder 12 calculates the deviation between the Q-axis current target value Iq ^* and the detected Q-axis current value Iq, and outputs it to the Q-axis current FB controller 14.
The adder 13 calculates a deviation between the D-axis current target value Id ^* and the detected D-axis current value Id and outputs the deviation to the D-axis current FB controller 15.
The Q-axis current FB controller 14 performs a PI control calculation by multiplying a deviation between the Q-axis current target value Iq ^* and the detected Q-axis current value Iq by a PI gain, and calculates a Q-axis voltage command value Vq ^* . The PI gain is changed in accordance with a command from the motor torque estimating means.

For example, the calculation according to the following equation is performed.
(Equation 3)

Vq ^* = Kp · (Iq ^* -Iq) + Ki · ∫ (Iq ^* -Iq) dt

Kp is a proportional gain and Ki is an integral gain.
The D-axis current FB controller 15 performs a PI control calculation that multiplies the deviation between the D-axis current target value Id ^* and the detected D-axis current value Id by a PI gain, and calculates a D-axis voltage command value Vd ^* . The PI gain is changed in accordance with a command from the motor torque estimating means.

For example, the calculation according to the following equation is performed.
(Equation 4)

Vd ^* = Kp · (Id ^* -Id) + Ki · ∫ (Id ^* -Id) dt

Kp is a proportional gain and Ki is an integral gain.
The inverter control signal calculation unit 16 performs the following calculation to calculate the three-phase command voltages (Vu ^* , Vv ^* , Vw ^* ). Vα ^* and Vβ ^* are intermediate variables and two-phase voltage command values. Further, θ is a rotation angle represented by an electrical angle (mechanical angle × number of pole pairs).

Further, the inverter control signal calculation unit 16 compares the three-phase command voltages (Vu ^* , Vv ^* , Vw ^* ) with the triangular wave to generate and output a switching signal.
The motor torque estimation unit 17 estimates the motor torque from the detected Q-axis current Iq and the detected D-axis current Id using the following equation.
(Equation 7)

  Tm = P ・ {ψa ・ Iq + (Ld-Lq) ・ Id ・ Iq}

Tm is the motor torque, P is the number of pole pairs (constant), ψa is the rotor magnet flux linkage (constant), Lq is the Q axis inductance (constant), Ld is the D axis inductance (constant), and Iq is the Q axis current. The actual value, Id, is the actual value of the D-axis current.
The current converter 18 obtains the Q-axis current Iq and the D-axis current Id from the detected three-phase currents Iu, Iv, and Iw using the following equations. The current values Iq and Id are actual values because they are obtained by converting the detected current.

These two equations are Park conversion and Clark conversion.
The three-phase current detector 19 detects currents (Iu, Iv, Iw) flowing through the U-phase, V-phase, and W-phase coils of the three-phase synchronous electric motor. Since the sum of all currents is 0 amperes, two of the three phases may be sensed using the relationship, and the rest may be calculated. In that case, it shall be according to the following formula.
(Equation 10)

  Iu =-(Iv + Iw)

The rotation angle detection unit 20 integrates the rotation speed estimated by the rotation speed detection unit 21 and calculates the rotation angle.
The rotation speed detector 21 estimates the rotation speed by an estimation calculation.
As an example of estimation calculation, the paper “The periodic speed fluctuation suppression control using BPF for PMSM position sensorless vector control for compressors” described in IEEJ Transaction (Industrial Application Division) Vol. 127, No. 7 The estimation calculation described in 1 is given.

FIG. 2 is a schematic explanatory diagram of the motor inverter 2.
The motor inverter 2 includes a three-phase AC synchronous motor 201, a power source 202 that is an inverter circuit, transistors 203 to 208, and current detection resistors 209 and 210.
The rotor structure of the three-phase AC synchronous motor 201 is assumed to be an embedded magnet type.
The power source 202 supplies driving power to the three-phase AC synchronous motor 201.
The transistors 203 to 208 each output to the three-phase (U-phase, V-phase, W-phase) coils of the three-phase AC synchronous motor 201. On the three-phase upper arm side, the emitters of the transistors 203 to 205 are connected to the respective three-phase coils, and the collector is connected to the power supply side. The input to the base is connected to the gate control signal from the inverter control signal calculation unit 16.

Next, on the three-phase lower arm side, the collectors of the transistors 206 to 208 are connected to each of the three-phase coils, and the emitter is connected to the feedback side to the power source. The input to the base is connected to the gate control signal from the inverter control signal calculation unit 16. The lower arm side receives an inverted waveform of the gate control signal on each upper arm side.
Further, among the three phases, current detection resistors 209 and 210 are provided on the two-phase lower arm side. The current values of the remaining phases are obtained by calculation (see the above formula 10). A shunt resistor is given as an example of the current detection resistors 209 and 210.

FIG. 3 is an explanatory diagram of a switching data table for the proportional gain Kp and the integral gain Ki in the Q-axis current FB controller 14 and the D-axis current FB controller 15.
In the Q-axis current FB controller 14 and the D-axis current FB controller 15 of the first embodiment, a predetermined value 250 is set for the motor torque value from the motor torque estimating unit 17 as shown in FIG. Below the predetermined value, the proportional gain Kp and the integral gain Ki in the feedback control by the PI control calculation are set to large values. When the predetermined value 250 is exceeded, the proportional gain Kp and the integral gain Ki are switched to small values.

The operation will be described.
[Torque vibration countermeasures, step-out countermeasures, operation to ensure a wide operating range]
In the control apparatus for the electric motor according to the first embodiment, the target opening speed is set and inputted by the control provided at the upper level, and the control is performed based on this.
For example, in the air conditioning control in the passenger compartment, the target rotational speed of the electric compressor is set.
On the other hand, in the control device for the electric motor, the AC synchronous motor is controlled by the vector control method so as to realize the target rotation speed.
FIG. 4 is an explanatory diagram of vector control of the electric motor control apparatus according to the first embodiment.
In this vector control, as shown in FIG. 4, an alternating current is converted into a direct current, and the D axis in the magnetic pole direction and the Q axis perpendicular to the magnetic pole are considered for a pair of magnetic pole rotors. Treat as Q-axis current.
Therefore, increasing the D-axis current increases the torque, and increasing the Q-axis current increases the rotational speed.

In the first embodiment, the target DQ-axis current command value calculation unit 11 calculates the DQ-axis current command value Ia from the deviation between the target rotation speed and the actual rotation speed, and the DQ-axis current distribution unit 113 calculates the DQ-axis current command value Ia. Distribute to the value Id ^* and Q-axis current target value Iq ^* .
Then, the Q axis current FB controller 14 and the D axis current FB controller 15 perform feedback control by PI control so that the detected values Id and Iq are brought close to the D axis current target value Id ^* and the Q axis current target value Iq ^*. Do.
The D-axis voltage command value and the Q-axis voltage command value obtained in this way are converted into three-phase command voltages (Vu ^* , Vv ^* , Vw ^* ) by the inverter control signal calculation unit 16, and the motor inverter Control to output to 2.

Here, when the structure of the rotor is an embedded magnet type, due to the spatial distortion of the magnetic flux, torque vibration occurs several times per rotation of the electrical angle, and six times in the first embodiment.
This torque vibration causes noise and vibration.
In order to suppress this torque vibration, the PI control gains of the Q-axis current FB controller 14 and the D-axis current FB controller 15 may be increased.
FIG. 5 is an explanatory diagram showing the influence of the gains of the Q-axis current target value Iq ^* and the detected value Iq.
As shown in FIG. 5 (a), when the detected value Iq of the Q-axis current is wavy due to the influence of torque vibration, if the feedback control PI gain is increased, the followability to the target value is improved. As a result, torque vibration is suppressed as shown in FIG.

However, when the PI gain is increased, the amplitude of the command voltage that is the operation amount of the current control increases. Here, when the command voltage reaches the power supply voltage, a state occurs in which the transistor of the motor inverter 2 is always turned off during one carrier cycle. In this case, the possibility of out-of-step becomes large because current detection cannot be performed.
FIG. 6 is an explanatory diagram showing a state in which a gate control signal is generated from a U-phase voltage command value and a triangular wave.
In the control apparatus for the electric motor of the first embodiment, the inverter control signal calculation unit 16 compares the three-phase command voltages (Vu ^* , Vv ^* , Vw ^* ) with the three-waves (see FIG. 6 (a)). A gate control signal is generated (see FIG. 6B). This gate control signal is a PWM control signal and is expressed by a duty ratio.

Although FIG. 6 shows the U phase as an example, the V phase and the W phase can be generated in the same manner.
In the example shown in FIG. 6, the power supply voltage is set to 200 v, and the U-phase voltage command value at 2000 rpm for a motor with three pole pairs is plotted. The period of the voltage changes with the rotation speed, and the amplitude of the voltage increases as the load torque increases.

  In the motor inverter 2, the transistors 203 to 208 and the current detection resistors 209 and 210 on the upper arm side and the lower arm side are as shown in FIG. Therefore, the current detection resistors 209 and 210 can detect current only during the time when the transistors 206 and 207 on the lower arm side are ON. Therefore, in the state where the transistors 206 and 207 are always off during one carrier cycle, the current cannot be detected and the possibility of step-out increases.

  Referring to FIG. 6 (b), the transistor on-time is short and the current detection becomes difficult at around 2.5 ms. Furthermore, the actual command voltage is not smooth as shown in FIG. 6A, and vibrates to suppress the current deviation. For this reason, if the amplitude of vibration is large, the power supply voltage is exceeded and current cannot be detected. When the current cannot be detected, feedback values for the feedback control of the D axis and the Q axis cannot be obtained, causing a control deviation and increasing the possibility of step-out.

  In order to avoid step-out, it is effective to lower the command voltage by lowering the target rotational speed, lowering the induced voltage proportional to the rotational speed, when the command voltage exceeds a predetermined value. However, as described above, when the PI gain is increased, the voltage amplitude increases, and the target rotational speed is lowered in a state where the generated torque is lower, and the operable region is narrowed.

In the first embodiment, the actual value Iq of the Q-axis current and the actual value Id of the D-axis current are obtained by the current conversion unit 18, and the actual value Iq of the Q-axis current and the D-axis current are obtained by the motor torque estimation unit 17. The motor torque is estimated from the actual value Id. The Q-axis current FB controller 14 and the D-axis current FB controller 15 increase the PI gain (Kp, Ki) when the motor torque is equal to or less than a predetermined value, and increase the PI gain when the motor torque exceeds the predetermined value 250. Reduce (Kp, Ki).
When the PI gain (Kp, Ki) is reduced, the waveform vibration amplitude of the three-phase command voltages (Vu ^* , Vv ^* , Vw ^* ) input to the inverter control signal calculation unit 16 is reduced.
Therefore, as described above, if the upper limit of the duty ratio to be used is set so that current detection is not impossible, the upper limit of the duty ratio can be increased by the vibration amplitude.

For example, the average duty can be increased from 83% to 90%. Even if it does in this way, since vibration amplitude is small, it will not cause trouble in performing current detection.
FIG. 7 is a graph showing the relationship between the rotational speed of the three-phase synchronous electric motor of Example 1 and the motor torque.
Referring to FIG. 7, if the maximum duty ratio is set in consideration of current detection, the duty ratio can be increased because the maximum torque decreases according to the rotational speed called NT characteristics. The part is moved to the high rotation side. That is, high rotation and high torque can be achieved.
That is, in other words, the fact that the duty ratio that can be actually used can be increased can ensure the wide range of the operable region.

  Furthermore, since the PI gain is increased below the predetermined value of the motor torque with a sufficient duty ratio, the current detection is not disabled, the step-out can be sufficiently prevented, and the PI gain is increased. Thus, torque vibration can be sufficiently suppressed. The suppression of torque vibration results in noise reduction.

Explain the effect.
In the control device for the electric motor according to the first embodiment, the following effects can be obtained.

(1) Target DQ-axis current command for setting the Q-axis current target value Iq ^* and the D-axis current target value Id ^* of the three-phase AC synchronous motor 201 based on the request of the motor inverter 2 to the three-phase AC synchronous motor 201 A value calculation unit 11, a three-phase current detection unit 19 that detects an alternating current (Iu, Iv, Iw) flowing in each phase, a rotation angle detection unit 20 that detects a rotation angle of the three-phase AC synchronous motor 201, and Current conversion unit 18 that performs Clark conversion and Park conversion on the alternating current (Iu, Iv, Iw) of the phase using the rotation angle and calculates the detected value Iq of the Q-axis current and the detected value Id of the D-axis current A Q-axis current FB controller 14 for calculating the Q-axis voltage command value Vq ^* by PI control so that the difference between the Q-axis current target value Iq ^* and the detected value Iq of the Q-axis current is small, and the D-axis from the detected value Id of the current target value Id ^* and D-axis current, by the PI control so that the difference becomes smaller A D-axis current FB controller 15 for calculating a-axis voltage command value Vd ^*, the rotation angle and Q-axis voltage command value Vq ^* and D-axis voltage command value Vd ^*, the motor inverter 2 for driving the 3-phase AC synchronous motor 201 The inverter control signal calculation unit 16 that calculates the control signals of the transistors 203 to 208 of the inverter and the motor torque estimation unit 17 that estimates the motor torque generated by the three-phase AC synchronous motor 201 are provided, and the Q-axis current FB controller 14 The D-axis current FB controller 15 reduces the P gain Kp and the I gain Ki of PI control when the motor torque is larger than the predetermined value 250 as compared to when the motor torque is smaller than the predetermined value 250. FIG. Therefore, when using an embedded magnet type as a synchronous motor (synchronous motor), torque vibration countermeasures, step-out countermeasures, and ensuring a wide operating range are ensured. It can be carried out in.

  (3) In the above (1), since the motor torque estimation unit 17 estimates the motor torque from the detected value Iq of the Q-axis current and the detected value Iq of the actual D-axis current, A motor torque can be obtained without providing a sensor and used for control.

  (4) In the above (1) or (3), the predetermined value 250 of the motor torque in the process of FIG. 2 of the Q-axis current FB controller 14 and the D-axis current FB controller 15 affects the current detection of the motor torque. Since it is set as a boundary when dividing into a range and a range that does not affect current detection, the PI gain is increased in the range of motor torque that does not affect current detection, so that current detection becomes impossible. In this case, the step-out can be sufficiently prevented and the torque vibration can be sufficiently suppressed by increasing the PI gain. Further, in a range where the motor torque is larger than a predetermined value that affects current detection, the PI gain can be reduced and the duty ratio can be increased so that a wide range of operation can be ensured.

(5) In the above (1), (3), (4), the rotation speed detector 21 for detecting the rotation speed of the three-phase AC synchronous motor 201 is provided, and the request to the three-phase AC synchronous motor 201 is the target rotation The target DQ-axis current command value calculation unit 11 is an adder 111 that calculates a deviation between the target rotation speed and the detected value of the rotation speed, and a DQ-axis current command by feedback control by multiplying the deviation by a speed gain. with a speed FB controller 112 for calculating the value Ia ^*, the DQ axes current distribution unit 113 for performing an operation to allocate DQ-axis current command value Ia ^* to the D-axis current target value Id ^* and Q-axis current target value Iq ^* Therefore, the control of the three-phase AC synchronous motor 201 can be easily controlled by the DC of the D axis and the Q axis, and sufficient speed feedback can be performed with respect to the target speed.

  (7) In the above (1), (3), (4), (5), the three-phase AC synchronous motor 201 is used for driving a compressor in a vehicle air conditioner, and therefore, torque vibration By the suppression, for example, when the vehicle performs an idle stop, the operation sound does not stand out, and the sound insulating material can be reduced. In addition, a small motor can be achieved by securing a wide operating range.

The second embodiment is an example in which the PI gain is gradually switched in the transition section when the motor torque becomes larger than a predetermined value of the motor torque.
The configuration will be described.
In the second embodiment, in the Q-axis current FB controller 14 and the D-axis current FB controller 15, when the motor torque from the motor torque estimation unit 17 becomes larger than a predetermined value and the PI gain is switched, switching is performed as follows. .
FIG. 8 is an explanatory diagram illustrating a PI gain switching data table according to the second embodiment.
When the motor torque becomes larger than a predetermined value, the P gain Kp and I gain Ki of the PI gain are gradually reduced in the provided transition section 260, and when the motor torque becomes larger than the transition section, the P gain Kp, The I gain Ki is set to a small constant value as shown in FIG.
This may be realized by a function and an operation, or FIG. 8 may be provided as table data or map data.

The operation will be described.
[Action to switch gain continuously]
Depending on the motor load of the motor inverter 2, the behavior at the time of switching the gain may not be preferable. For example, it may lead to a person feeling a change in load as a feeling of strangeness.
In such a case, as in the second embodiment, gradual switching in the gain transition section shown in FIG. 8 is effective.

Explain the effect. In addition to the above (1), (3), (4), (5), the electric motor control device of Embodiment 2 has the following effects.
(6) In the above (1), (3) to (5), the gain changing process of the Q-axis current FB controller 14 and the D-axis current FB controller 15 is controlled by PI control when the motor torque is larger than a predetermined value. When the P gain and I gain are reduced, a transition section is provided in the motor torque, and the process of FIG. 8 is gradually reduced in the transition section. It is possible to prevent people from feeling uncomfortable.

The control device for the electric motor according to the third embodiment is an example in which the predetermined value of the motor torque is determined from the rotation speed of the three-phase AC synchronous motor.
The structure will be described.
FIG. 9 is a block diagram of the electric motor control apparatus according to the third embodiment.
FIG. 10 is an explanatory diagram of a PI gain switching data table according to the third embodiment.
In the third embodiment, the Q-axis current FB controller 14 and the D-axis current FB controller 15 determine the predetermined value of the motor torque corresponding to the rotation speed from the table data shown in FIG. 301 is set.
Then, the motor torque from the motor torque estimating unit 17 is compared with a predetermined value, and the PI gain is changed when the motor torque is larger than the predetermined value.

This predetermined value 301 is predetermined in the region A where the motor torque is constant with respect to the rotational speed when the rotational speed is taken on the horizontal axis and the motor torque is taken on the vertical axis and the maximum torque characteristic 302 (NT characteristic) is shown. The value 301 is set to a value larger than the maximum characteristic value so that the maximum characteristic of the motor torque can be exhibited. This area A is on the low speed side.
Next, in the region B on the higher speed side than the region A, the maximum torque characteristic 302 in which the maximum motor torque gradually decreases with respect to the rotation speed is obtained. In this region B, the predetermined value 302 is set so that the motor torque is slightly lower than the maximum torque characteristic 302.

  Region B is a rotational speed region in which current detection may not be possible. This is because the duty ratio does not become a limit in the characteristic portion where the maximum torque is constant with respect to the rotation speed in the region A. Actually, the current value is limited. On the other hand, in the characteristic portion where the maximum torque decreases with respect to the rotation speed in the region B, the duty ratio may be limited because it is limited by the voltage. That is, at high speed, the back electromotive force of the motor increases.

  Therefore, the setting table data (FIG. 10) of the predetermined value in the second embodiment is, in other words, described as a predetermined value for changing the gain by setting a torque value slightly lower than the maximum torque in a region where current detection may not be possible. Will be.

The operation will be described.
[Torque vibration countermeasures, step-out countermeasures, operation to ensure a wide operating range]
In the third embodiment, the maximum torque characteristic 302 (NT characteristic) of the three-phase AC synchronous motor 201 of the motor inverter 2 is obtained in advance by experiments or the like, and a predetermined value as shown in FIG. Is table data that changes according to the rotation speed.
Then, the Q-axis current FB controller 14 and the D-axis current FB controller 15 set a predetermined value according to the rotation speed from the rotation speed detection unit 21, and the motor torque from the motor torque estimation unit 17 is determined from the predetermined value. When becomes larger, the PI gain is changed to be smaller.

  Here, the PI gain (Kp, Ki) is reduced in consideration of the maximum torque characteristic of the three-phase AC synchronous motor 201 corresponding to the rotational speed. Therefore, the gain is increased as much as possible in consideration of the characteristics. Therefore, suppression of torque vibration and prevention of step-out are further improved. Nevertheless, in areas where current detection may be impossible, the PI gain will be reduced immediately before reaching the maximum torque according to the rotation speed, and operation is possible without making current detection reliably impossible. Secure a wide area.

Explain the effect. In addition to the effects (1), (4), and (5), the electric motor control apparatus according to the third embodiment has the following effects.
(2) A rotation speed detection unit 21 that detects the rotation speed of the three-phase AC synchronous motor 201 is provided, and the gain change processing is performed by changing a predetermined value of the motor torque according to the rotation speed of the three-phase AC synchronous motor 201 in FIG. In the area where current detection may be impossible while increasing PI gain as much as possible in consideration of motor characteristics and further improving suppression of torque vibration and prevention of step-out in order to determine by data Thus, it is possible to ensure a wide range of the operable region without reliably making the current detection impossible.

  As mentioned above, although the control apparatus of the electric motor of this invention has been demonstrated based on Example 1-3, it is not restricted to these Examples about a concrete structure, Each claim of a claim Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.

  The rotation angle detection unit and the rotation speed detection unit may be provided separately, or either one may be detected and the other may be obtained by calculus. The rotation angle detection unit and the rotation speed detection unit may be either directly detected by an encoder or the like, or indirectly detected by current or voltage.

The three-phase AC synchronous motor may be used for driving a hybrid vehicle (HEV), or may be used for driving an electric vehicle (EV). Suppression of torque vibration leads to a reduction in operating noise, and securing a wide driving range leads to miniaturization of the motor.
In the embodiment, the inverter is composed of a transistor, but another switching element may be used.

It is a figure which shows the block configuration of the control apparatus of the electric motor of Example 1. FIG. It is outline | summary explanatory drawing of a motor inverter. It is explanatory drawing of the switching data table of the proportional gain Kp and integral gain Ki in a Q-axis current FB controller and a D-axis current FB controller. It is explanatory drawing of the vector control of the control apparatus of the electric motor of Example 1. FIG. It is explanatory drawing which shows the influence of the gain of Q-axis current target value Iq ^* and detected value Iq. It is explanatory drawing which shows the state which produces | generates a gate control signal from the voltage command value and triangular wave of U phase. It is a graph which shows the relationship between the rotational speed of the three-phase synchronous electric motor of Example 1, and a motor torque. FIG. 10 is an explanatory diagram illustrating a PI gain switching data table according to the second embodiment. It is a figure which shows the block configuration of the control apparatus of the electric motor of Example 3. FIG. 12 is an explanatory diagram illustrating a PI gain switching data table according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric motor control apparatus 2 Motor inverter 11 DQ-axis current command value calculating part 111 Adder 112 Speed FB controller 113 DQ-axis current distribution part 12 Adder 13 Adder 14 Q-axis current FB controller 15 D-axis current FB controller 16 Inverter control signal calculation unit 17 Motor torque estimation unit 18 Current conversion unit 19 Three-phase current detection unit 20 Rotation angle detection unit 21 Rotation speed detection unit 201 Three-phase AC synchronous motor 202 Power supply 203 to 208 Transistor 209 Current detection resistor 210 Current detection Resistance 250 Predetermined value 260 Transition region 301 Predetermined value 302 Maximum torque characteristic 302 Predetermined value
Ia DQ axis current command value
Iq Actual value of Q-axis current
Id Actual value of D-axis current
Iq ^* Q axis current target value
Id ^* D-axis current target value
Ki integral gain
Kp proportional gain
Iu U phase current
Iv V phase current
Iw W phase current
Vd ^* D-axis voltage command value
Vq ^* Q-axis voltage command value

Claims (7)

A target DQ-axis current command value calculating means for setting a target Q-axis current and a target D-axis current of the three-phase AC synchronous motor based on a request to the three-phase AC synchronous motor;
Three-phase current detection means for detecting an alternating current flowing in each phase;
Rotation angle detection means for detecting the rotation angle of the three-phase AC synchronous motor;
Current conversion means that performs Clark conversion and Park conversion on the alternating current of each phase using the rotation angle, and calculates an actual Q-axis current and an actual D-axis current;
Q-axis command value calculation means for calculating a Q-axis voltage command value by PI control so that a difference between the target Q-axis current and the actual Q-axis current is small;
D-axis command value calculation means for calculating a D-axis voltage command value by PI control so that the difference between the target D-axis current and the actual D-axis current is small;
An inverter control signal calculation means for calculating a control signal of a switching element of an inverter that drives the three-phase AC synchronous motor from the Q-axis voltage command value, the D-axis voltage command value, and the rotation angle;
Motor torque estimating means for estimating a motor torque generated by the three-phase AC synchronous motor;
With
The Q-axis command value calculating means and the D-axis command value calculating means are configured so that when the motor torque is larger than a predetermined value, the P gain and I gain of PI control are compared with when the motor torque is smaller than a predetermined value. With gain changing means to reduce
An electric motor control device characterized by the above. In the control apparatus of the electric motor according to claim 1,
A rotation speed detecting means for detecting the rotation speed of the three-phase AC synchronous motor is provided;
The gain changing means determines a predetermined value of the motor torque according to the rotation speed of the three-phase AC synchronous motor.
A control apparatus for an electric motor. In the control apparatus for the electric motor according to claim 1 or 2,
The motor torque estimating means estimates the motor torque from the actual Q-axis current and the actual D-axis current;
A control apparatus for an electric motor. In the control apparatus of the electric motor according to claim 1,
The predetermined value of the motor torque of the gain changing means is set as a boundary when the motor torque is divided into a range that affects current detection and a range that does not affect current detection.
A control apparatus for an electric motor. In the control apparatus of the electric motor of any one of Claims 1-4,
A rotation speed detecting means for detecting the rotation speed of the three-phase AC synchronous motor is provided;
The request for the three-phase AC synchronous motor is a target rotational speed,
The target DQ axis current command value calculating means is:
A deviation calculator for calculating a deviation between the target rotational speed and a detected value of the rotational speed;
Speed feedback calculating means for multiplying the deviation by a speed gain and calculating a DQ axis current command value by feedback control;
DQ axis current distribution means for performing calculation to distribute the DQ axis current command value to the target D axis current and the target Q axis current;
An electric motor control device comprising: In the control apparatus of the electric motor of any one of Claims 1-5,
The gain changing means of the Q-axis command value calculating means and the D-axis command value calculating means is configured to adjust the motor torque when the P gain and I gain of PI control are reduced when the motor torque is larger than a predetermined value. Provide a transition section and gradually reduce it in the transition section.
A control apparatus for an electric motor. In the control apparatus of the electric motor of any one of Claims 1-6,
The three-phase AC synchronous motor is used to drive a compressor in a vehicle air conditioner.
A control apparatus for an electric motor.

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