JP3738865B2 - IPM motor control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for controlling the speed and torque of an IPM motor, which is a synchronous motor having a structure in which a permanent magnet is embedded in a rotor (see, for example, Japanese Utility Model Laid-Open Nos. 4-28745 and 3-97354).
[0002]
[Prior art]
FIG. 2 is a block diagram showing a configuration of a general IPM motor driving apparatus. In the conventional example, as shown in FIG. 2, an IPM motor 502 connected to a load 504, a rotation detector 503 for detecting the rotation of the IPM motor 502, a drive control device 500 for controlling the driving of the IPM motor 502, and an IPM A cable 505 that connects the motor 502 and the drive control device 500, a signal cable 507 that connects the rotation detector 503 and the drive device 500, and the drive control device 500 sends the control signal to the IPM motor 502. The power conversion unit 501 that converts power to drive, the dq axis current control unit 531 that controls the current and rotating magnetic field that flows through the armature of the IPM motor 502, the speed, torque, constant output characteristics, etc. of the IPM motor 502 It is comprised by the application control part 521 to control.
In the drive device configured as described above, the power output from the power conversion unit 501 is supplied to the IPM motor 502 via the motor circuit cable 505, and the power supplied from the IPM motor 502 is converted to the torque of the rotor. The load 504 is driven by the rotational torque after the conversion. The rotation of the IPM motor 502 is detected by the rotation detector 503 and input to the drive control device 500 via the signal cable 507.
[0003]
Below, the drive method of an IPM motor is demonstrated. FIG. 3 is a conventional control block diagram. First, in the dq axis current control unit 531, the rotation signal of the IPM motor 502 detected by the rotation detector 503 is input to the rotation position signal calculator 536 and the speed detection signal calculator 537 via the cable 507. The rotational position θ of the magnetic pole is calculated from the input signal by the rotational position calculator 536, and the calculation result is output to the coordinate converter 535 and the coordinate converter B 532.
Next, the coordinate converter A535 uses u of the three-phase currents flowing through the IPM motor 502 detected by the current detector 506 using the rotation angle signal θ of the magnetic pole output from the rotation position signal calculator 536. The currents iu and iv flowing in the phase and the v phase are converted into signals Id and Iq of two-phase dq axis coordinates.
Next, the d-axis obtained by feeding back the d-axis current and the q-axis current Iq output from the coordinate converter A535 to the d-axis current command Id and the q-axis current Iq ^* calculated by the application control unit 521. The q-axis current control deviation signal is input to the current control deviation signal d-axis current controller 534 and the q-axis current controller 533, respectively.
Then, the speed detection signal calculator 537 obtains the motor rotation speed ωr from the signal from the rotation detector 503.
Next, the motor rotation speed ωr, the d-axis current command Id ^*, and the q-axis current finger Iq ^* are input to the feedforward compensator 538, and a disturbance compensation signal for canceling the induced voltage that is a disturbance of the dq-axis current control. Is calculated.
Next, a disturbance compensation signal is added to a signal obtained by amplifying the deviation signal of the d-axis current control in the d-axis current controller 534 provided with a proportional integration calculator, and the signal is converted into a coordinate converter as a d-axis voltage command Vd ^* . It is input to B532.
Similarly, a signal disturbance compensation signal obtained by amplifying the deviation signal of the q-axis current is added in the q-axis current controller 533 provided with a proportional integration calculator, and the signal is converted into a coordinate converter B532 as a q-axis voltage command Vq ^*. Is input.
Next, in the coordinate converter B532, the dq-axis two-phase voltage command of the d-axis voltage command Vd ^* and the q-axis voltage command Vq ^* is converted into a three-phase voltage command of Vu ^* , Vv ^* , Vw ^* and PWM control 511. Is input.
Next, in the PWM controller 511, the current converter 509 is operated in response to the three-phase commands Vu ^* , Vv ^* , Vw ^* , and the voltage is controlled by the IPM motor 502 at a frequency required for drive control. Currents iu ^* , iv ^* , and iw ^* are passed through each phase 502.
[0004]
The operation of the application control unit 521 will be described below.
The motor speed signal ωr calculated and output by the speed detection signal calculator 537 is fed back to the speed command signal ωr ^* , and the deviation signal is input to the speed controller 522 having proportional integration and amplified. The signal is output to the dq axis current command calculator 523 as the motor torque command T ^* . The dq-axis current command calculator 523 calculates a d-axis current command Id ^* and a q-axis current command Iq ^* corresponding to the required motor torque from the motor torque command T ^*, and outputs them to the dq-axis current control unit 531. (Conventional example 1).
Further, as a conventional example 2, in a drive control device that uses a battery as a power source and converts it into an AC power source according to a torque command value to drive a permanent magnet synchronous motor, either the torque command value or the motor output state is a predetermined amount or more. When the battery voltage is changed, the battery voltage is considered to be the reference minimum voltage, and the initial current command value is obtained according to the torque command value, the motor output state, and the reference minimum voltage, and driving is performed based on the obtained initial current command value. When the battery voltage detected after the execution of the vector control of the motor current based on the initial current command value and the initial control means for vector control of the current is stabilized, the optimum current command value corresponding to the detected battery voltage is obtained and the obtained current Japanese Patent Application Laid-Open No. 7-246000 is provided with current correction means for vector-controlling the motor current based on a command value.
[0005]
[Problems to be solved by the invention]
However, the conventional one described above has the following problems.
When the voltage V1 of the AC power supply 550 supplied to the power conversion unit 501 is higher than the minimum voltage V1 _MIN required for stably controlling the motor 502, the voltage output from the 501 power conversion unit is necessary for the motor 502. Therefore, the d-axis current and q-axis current according to the d-axis current command Id ^* and the q-axis current command Iq ^* calculated by the application control unit 521 can flow, and the motor 502 is stabilized. Can be controlled.
However, when the voltage V1 of the AC power source 500 becomes lower than the minimum voltage V1 _{MIN, the} voltage output from the power conversion unit 501 to the motor 502 is insufficient, so that the d axis calculated by the application control unit 521 is used. The current according to the current command Id ^* and the q-axis current command Iq ^* cannot actually be supplied. The dq axis current control unit 531 becomes uncontrollable, and the rotating magnetic field of the electric motor 502 and the rotor are out of synchronization, and the operation becomes impossible.
In the prior art, the rated voltage of the IPM motor 502 is designed with a sufficient margin in advance so that the control of the IPM motor 502 does not become unstable when the voltage of the AC power supply decreases. As a result, the rated current of the IPM motor 502 is increased and the capacity of the power conversion unit 501 is increased.
Conventional Example 2 has the following problems. A response at the time of sudden load change is made with the minimum current of the d-axis and q-axis with respect to the torque command and the minimum voltage obtained as a result of the rotation speed, but when the load changes more than expected, the d-axis, q No response was possible with the minimum shaft current. Further, since the d-axis current command and the q-axis current command based on the torque command are changed independently, the relationship between the actual torque and the torque command has no linearity.
The present invention has been made in view of the above-described problems associated with the conventional technology. Even if the voltage Vdc of the DC output circuit of the power converter 109 decreases due to a voltage drop of the power supply, the IPM motor 502 is provided. It is an object of the present invention to prevent an undervoltage condition from being caused, to enable stable control, and to determine a rated voltage of the IPM motor 502 high.
[0006]
[Means for Solving the Problems]
In order to solve the above problem, the present invention is a synchronous motor having a structure in which a permanent magnet is embedded in a rotor. Control the d-axis current and the q-axis current according to the d-axis current command Id ^* and the q-axis current command Iq ^* calculated from the torque command T ^* output from the speed controller for the d-axis current and the q-axis current of the IPM motor. In the IPM motor control method for controlling the speed and torque of the IPM motor by:
When the output voltage Vdc of the DC power converter is higher than the output voltage set value Vdcr of the DC power converter, the d-axis current is determined according to the d-axis current command Id ^* calculated from the torque command T ^* output from the speed controller. When the output voltage Vdc is lower than the output voltage set value Vdcr, the primary voltage command V1 ^{* is set} to V1 ^* = (Vdc / Vdcr) V1r, and the primary voltage signal V1FB is set to V1FB = (Vd ^{* 2} + Vq ^{* 2} ) ^1/2, and a torque command output from the speed controller with a d-axis current command correction signal Idx ^* obtained from a deviation signal between the primary voltage command V1 ^* and the primary voltage signal V1FB The d-axis current is controlled in accordance with the d-axis current command Id1 ^* added to the d-axis current command Id ^* calculated from T ^* .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
First, the principle of control for reducing the primary induced voltage of the IPM motor will be described.
Equations (1) to (2) are well-known voltage equations showing the operation state of the IPM motor in the dq coordinate system.
Vd = (R + Ld S) Id -Pωr Lq Iq (1)
Vq = Pωr Ld Id + (R + Lq S) Iq + Pωr φ1 (2)
Where Vd is the d-axis voltage, Vq is the q-axis voltage, R is the winding resistance for one phase, Ld is the d-axis inductance, Lq is the q-axis inductance, ωr is the rotational angular velocity of the rotor, P is the number of pole pairs, φ1 is the maximum value of the IPM motor primary linkage flux, and S is the Laplace operator.
[0008]
To make the explanation of the control principle easier to understand, we will consider steady-state operation, and ignore the terms multiplied by the Laplace operator in Eqs. (1) and (2). Also, ignoring the effect of winding resistance R for one phase, equations (1) and (2) are approximated as equations (3) and (4).
Vd = -Pωr Lq Iq (3)
Vq = Pωr Ld Id + Pωr φ1 (4)
Known formulas relating to the torque T, d-axis current Id, and q-axis current Iq of the IPM motor are shown in equations (5) and (6).
T = Pm ₁ [φ1- (Lq-Ld) Id] Iq (5)
Here, m ₁ is the number of phases of the IPM motor.
A known relational expression between the primary voltage V1 of the IPM motor and the d-axis voltage Vd and the q-axis voltage Vq is shown in equation (6).
^{V1 = (Vd 2 + V q} 2) 1/2 (6)
Equation (6) is transformed into Equation (7) using Equations (3), (4), and (5).
V1 = Pωr φ1 [(1 + Ld Id / φ1) ² + (Lq / (P ² m ₁ ² φ1 ³ ))
・ (T / (1-Id (Lq-Ld) / φ1)) ² ] ^1/2 (7)
The first term inside the square root of the equation (7) becomes smaller as -φ1 / Ld ≦ Id <0 and Id approaches -φ1 / Ld.
Further, the second term within the square root decreases as Id increases in the negative direction when the torque T of the IPM motor is constant.
Equation (7) shows that the primary induced voltage of the IPM motor can be lowered by passing a negative d-axis current Id.
Next, a method for enabling the d-axis current and the q-axis current to be stably controlled even when the voltage V1 of the AC power supply supplied to the power converter is lowered will be described.
[0009]
If the DC voltage Vdc on the output side of the DC converter of the power converter is higher than the DC voltage Vdcr required to output the rated voltage V1r to the primary side of the IPM motor, the power converter requires an IPM motor. Therefore, it is not necessary to increase the d-axis current value in order to reduce the primary induced voltage of the IPM motor.
A control method in the case where the voltage V1 of the AC power supply supplied for power conversion is lowered and the DC voltage Vdc on the output side of the DC converter is lowered to Vdcr or less will be described.
The primary voltage command V1 ^* of the IPM motor is calculated from the DC voltage Vdc trained by the voltage detector provided on the output side of the DC converter of the power converter, the preset Vdcr and the primary rated voltage V1r of the IPM motor.
V1 ^* = (Vdc / Vdcr) V1r (8)
The primary voltage feedback signal V1FB of the IPM motor in accordance with Equation 19 from the d-axis voltage command Vd ^* of the d-axis current control unit and the q-axis voltage command Vq ^* of the q-axis current control unit with respect to the primary voltage command V1 ^* of the IPM motor Is calculated.
V1FB = (Vd ^{* 2} + Vq ^{* 2} ) ^1/2 (9)
Primary voltage command of said IPM motor, V1 ^* and the said amplified and obtained d-axis current command correction signal Idx ^* by the deviation signal of the primary voltage feedback signal V1FB the IPM motor and proportional-plus-integral calculator By performing d-axis current control according to the d-axis current command obtained by adding to the d-axis current command Id ^* calculated from the torque command T ^* output from the speed controller, the primary induced voltage of the IPM motor By lowering the value, the d-axis and q-axis currents can be stably controlled.
[0010]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an embodiment of a control device for an IPM motor of the present invention. A speed controller 122 provided with a proportional integral of a deviation signal between the motor speed command ωr and the motor rotation speed signal ωr ^* calculated from the signal detected by the motor rotation detector 103 in the speed detection signal calculator 137. , The deviation signal is amplified and output as a motor torque command T ^* .
The dq-axis current command calculator 123 calculates a d-axis current command Id ^* and a q-axis current command Iq ^* as a function of the motor torque command T ^* .
In the motor primary voltage command calculator 124, the motor primary voltage command V1 ^* is calculated from the output voltage Vdc of the DC converter 108 of the power converter 101 detected by the voltage detector 110 as follows.
[0011]
When the output voltage of the DC power converter 108 required for applying the rated voltage V1r of the motor is Vdcr, when Vdc ≧ Vdcr, the motor primary voltage commander 124 sets the primary voltage command V1 ^* = V1r. Output.
When Vdc <Vdcr, the motor primary voltage command unit 124 outputs the primary voltage command V1 ^* = (Vdc / Vdcr) V1r.
In the motor primary voltage controller 125, the motor primary voltage is converted from the motor d-axis voltage command value Vd ^* and the q-axis voltage command value Vq ^* by the motor primary voltage feedback signal calculator 126 based on the equation (9). The signal obtained by amplifying the signal of the deviation between the obtained primary voltage feedback signal V1FB and the primary voltage command value V1 ^* by the proportional integrator 127 by the proportional integrator amplifier 127 is calculated. Is input.
In the signal limiter 128, if the output signal of the proportional integration amplifier 126 is positive, 0 is output, and if it is negative, the output signal of the proportional integration amplifier 126 is output as it is as the d-axis current command correction signal Idx ^* .
A d-axis current command is obtained by adding a d-axis current command correction signal Idx ^* output from 125 to the motor primary voltage controller to the d-axis current command Id1 ^* output from the dq-axis current command calculator 123. Id ^* is calculated. The d-axis and q-axis currents are controlled according to the d-axis current command and the q-axis current command Iq ^* calculated as described above.
The d-axis current corresponding to the decrease in the DC voltage on the output side of the DC converter of the power conversion unit even when the AC power supply voltage supplied to the power conversion unit of the drive control device of the IPM motor is decreased by the above means. , The primary induced voltage of the IPM motor is lowered to avoid a shortage of voltage applied to the IPM motor, and dq axis battery current control of the IPM motor is stably controlled.
[0012]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
Even when the AC power supply voltage supplied to the power conversion unit of the drive control device is lowered when the motor is operated near the rated voltage, the induced voltage of the motor is lowered and applied to the motor by the control method of the present invention. The rated voltage of the power conversion unit can be increased by preventing the voltage from becoming insufficient and enabling the dq axis current to be stably controlled.
In addition, the linearity of the actual torque with respect to the torque command can be maintained in response to a decrease in the AC power supply voltage or a sudden load change.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of an embodiment of an IPM motor control apparatus of the present invention.
FIG. 2 is a block diagram showing a general IPM motor drive device.
FIG. 3 is a conventional control block diagram.
[Explanation of symbols]
100 AC power supply 101 Power converter 102 IPM motor 103 Rotation detector 104 Load 105 Motor circuit cable 106 Current detector 109 Power converter 111 PWM controller 107 Signal cable 121 Application controller 122 Speed controller 123 dq axis current command calculator 124 motor primary voltage command device 125 motor primary voltage controller 126 motor primary voltage feedback signal calculator 127 proportional integration amplifier 128 signal limiter 131 dq axis current control unit 132 coordinate converter B
133 q-axis current controller 134 d-axis current controller 135 Coordinate converter A
136 Rotational position signal calculator 137 Speed detection signal calculator 138 Feed forward compensator

Claims (1)

D-axis current command Id ^* and q-axis current obtained by calculating the d-axis current and q-axis current of the IPM motor, which is a synchronous motor having a permanent magnet embedded in the rotor, from the torque command T ^* output from the speed controller In the IPM motor control method for controlling the speed and torque of the IPM motor by controlling the d-axis current and the q-axis current according to the command Iq ^* ,
When the output voltage Vdc of the DC power converter is higher than the output voltage set value Vdcr of the DC power converter, the d-axis current is determined according to the d-axis current command Id ^* calculated from the torque command T ^* output from the speed controller. When the output voltage Vdc is lower than the output voltage set value Vdcr, the primary voltage command V1 ^{* is set} to V1 ^* = (Vdc / Vdcr) V1r, and the primary voltage signal V1FB is set to V1FB = (Vd ^{* 2} + Vq ^{* 2} ) ^1/2, and a torque command output from the speed controller with a d-axis current command correction signal Idx ^* obtained from a deviation signal between the primary voltage command V1 ^* and the primary voltage signal V1FB A method for controlling an IPM motor, comprising: controlling a d-axis current according to a d-axis current command Id1 ^* added to a d-axis current command Id ^* calculated from T ^* .

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