JP2013038970A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent sudden change of current when performing a mode change.SOLUTION: A PI operation unit 26 of a motor controller calculates a proportional by multiplying a current deviation by a proportional gain and an integration term by multiplying an integrated value of the current deviation by an integral gain on the basis of the current deviation that is a difference between a current command of a motor calculated based on an output torque command of the motor 14 and an actual current of the motor actually measured, and then calculates a supply voltage command to the motor based on the proportional and the integration term. A control mode of the motor includes: an overmodulation control mode which obtains a sine wave output limited by a PWM control; and a PWM mode which obtains a sine wave output by the PWM control. If the current deviation is large when shifting from the overmodulation control mode to the PWM control, the proportional gain is decreased.

Description

  The present invention multiplies the current deviation by a proportional gain based on a current deviation that is the difference between the motor command current calculated based on the output torque command of the motor and its rotation state and the actual current of the motor actually measured. The motor control device calculates a supply voltage command to the motor from the integral term obtained by multiplying the integral term obtained by multiplying the integral value of the current deviation and the integral value of the current deviation by an integral gain.

  2. Description of the Related Art Conventionally, a hybrid motor, an electric vehicle, and the like are equipped with a driving motor, and a motor control device that controls the motor is used.

  In this motor control, electric power from the battery is converted into a three-phase motor drive current by an inverter, and also converted into a motor current according to a motor output torque command by PWM control. Further, when the vehicle is decelerated, the regenerative braking of the motor is performed by the inverter, and the regenerative power is returned to the battery.

  In such control, normally, the switching of the inverter is PWM controlled, the motor drive current is controlled, and the motor output torque is controlled. It is preferable to make the motor current a sine wave by such PWM control. However, if the motor current is made a sine wave by PWM control, a sufficient output torque cannot be obtained in the high rotation speed region. , Overmodulation PWM control and rectangular wave control are employed.

JP 2010-178444 A JP 2011-00389 A

  Here, when the drive mode is switched as described above, since the control content is different, the motor drive may not be appropriate at the time of the mode switch. For example, during grip after slipping, the load on the motor increases and the motor current increases, so switching from the rectangular wave mode to the overmodulation mode to the PWM mode is performed. At this time, in the rectangular wave mode and the overmodulation mode, when the mode is switched to the PWM mode due to the control with a relatively large time constant, the regenerative state is set despite the power running state. There was a case where it became.

  The present invention relates to a proportionality obtained by multiplying the current deviation by a proportional gain based on a current deviation that is a difference between a motor current command calculated based on a motor output torque command and an actual current measured by the motor. And an integral term obtained by multiplying the integral value of the current deviation and the integral value of the current deviation, and a supply voltage command to the motor is calculated based on the obtained proportional term and integral term. The motor control mode includes an overmodulation mode that obtains a motor current that is limited at a place with a large amplitude by PWM control, and a PWM mode that obtains a sine wave motor current by PWM control. When shifting from PWM to PWM control mode, if the current deviation is large, the proportional gain is changed to be small.

  Further, at the time of the mode transition, the integral term is reset to the voltage command value immediately before, and the integral term based on the current current deviation is added to the reset integral term to calculate the present integral term. Is preferred.

  Further, the present invention is obtained by multiplying the current deviation by a proportional gain based on a current deviation that is a difference between a motor current command calculated based on a motor output torque command and an actual measured motor actual current. The motor control device calculates a proportional term and an integral term obtained by multiplying the integral value of the current deviation by an integral gain, and calculates a voltage command to the motor based on the obtained proportional term and integral term. As a motor control mode, there are an overmodulation mode for obtaining a motor current that is limited by PWM control, and a PWM mode for obtaining a sinusoidal motor current by PWM control. From the overmodulation control mode to the PWM control mode When the sign of the calculated voltage command is reversed from that of the previous voltage command, the proportional gain is changed so that the sign is not reversed. And features.

  According to the present invention, when the overmodulation mode is switched to the PWM mode, it is possible to prevent the voltage command from changing greatly and entering the regenerative state despite the power running state.

It is a figure which shows the structure of the drive system of the vehicle containing the motor control apparatus which concerns on embodiment. It is a figure explaining the situation when a problem arises. It is a figure which shows the state of the current command at the time of mode switching. It is a flowchart of a Kp change process. It is a figure which shows the state of the current command at the time of mode switching.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a vehicle drive system including a motor control device according to an embodiment.

  DC power from the DC power supply 10 is converted into a desired three-phase current by the inverter 12 and supplied to the motor 14. The DC power supply 10 may be formed of a secondary battery such as a lithium ion battery or a nickel metal hydride battery, may have an output of several hundred volts, and may be boosted by a boost converter. The inverter 12 has, for example, three arms composed of two transistors (for example, IGBTs) connected in series between the positive and negative buses, and the middle point of each arm serves as an output terminal. Outputs alternating current. The motor 14 is a permanent magnet motor, and is driven by flowing currents of 120 degrees in the three phases of UVW. The motor 14 is a motor generator configured by, for example, a permanent magnet motor and generating electric power by driving and regenerating the vehicle.

  The current flowing through each phase of the motor 14 is detected by the ammeter 20, and the detected current value is supplied to the UVW → dq conversion unit 22. In addition, since each phase current detects the remaining one-phase current if the two-phase current is detected, the two-phase motor currents Iv0 and Iw0 of V and W are detected in this example. Further, the rotor angle θ of the motor is detected by a rotation angle detector (for example, a resolver) 24 and supplied to the UVW → dq conversion unit 22.

  The UVW → dq conversion unit 22 converts the motor currents Iu0, Iv0, and Iw0 to the dq axis to obtain the real d-axis current Id0 and the real q-axis current Iq0, and supplies them to the PI calculation unit 26.

  Here, the torque command indicating the target output torque of the motor obtained based on the accelerator depression amount of the vehicle is supplied to the current command generator 28. The current command generator 28 generates a target d-axis current Id * and a target q-axis current Iq * according to the torque command, and supplies them to the PI calculator 26.

  The PI calculation unit 26 subtracts the actual d-axis current Id0 and the actual q-axis current Iq0 from the target d-axis current Id * and the target q-axis current Iq *, calculates a deviation for the dq-axis current, and based on this, the target current Is supplied to the motor 14, the d-axis voltage command Vd and the q-axis voltage command Vq are calculated.

  The obtained d-axis voltage command Vd and q-axis voltage command Vq are converted into three-phase voltage commands Vu, Vv, Vw in the dq → UVW conversion unit 30 and supplied to the signal generation unit 32.

  The signal generator 32 basically generates a PWM control signal. That is, the voltage commands Vu, Vv, and Vw are compared with the PWM carrier to generate a PWM control signal having a duty ratio determined in accordance with the voltage commands Vu, Vv, and Vw. Controls switching. As a result, the motor current of each phase is controlled to the target value, and the output torque of the motor 14 is controlled according to the torque command.

  Here, in the above description, the control of the motor current has been described as being performed by PWM control. However, in the present embodiment, the control mode includes an overmodulation mode and a rectangular wave mode in addition to the PWM mode. Yes. In the PWM mode, a sinusoidal motor current is obtained. On the other hand, in the overmodulation mode, a sine wave motor current with a limit is obtained at a location with a large amplitude, and in the rectangular wave mode, a rectangular wave motor current is obtained.

  In this way, the overmodulation mode and the rectangular wave mode are provided because the sine wave PWM has a maximum modulation rate of 0.61, and in the case of a modulation rate higher than that, a voltage having an amplitude larger than the amplitude of the PWM carrier. This is because an overmodulation mode using a command and a rectangular wave mode in which the motor voltage command is a rectangular wave are used. In the low to medium speed range, there is no problem in the PWM mode, so the PWM mode is adopted. Also, an overmodulation mode is used to improve the output in the medium speed range, and a rectangular wave mode is used to improve the output at high speed. In terms of modulation rate, the mode is switched such as 0 to 61: PWM mode, 0.61 to 0.78: overmodulation mode, 0.78 or more: rectangular wave mode.

  Here, in the rectangular wave mode, the output torque control of the motor 14 is performed by the phase control of the rectangular wave, but the description thereof is omitted.

  In the PWM mode and the overmodulation mode, the motor current is feedback-controlled. Then, when the mode change is performed when the motor rotation speed is greatly changed, there is a problem that the running is not smooth.

  FIG. 2 shows a situation when a problem occurs. In this case, after the running state becomes slip and the motor rotational speed increases, the motor rotational speed decreases by gripping.

  For example, when a tire rides on a convex part, a slip occurs, the convex part is overcome while slipping, and the tire grips, such a state occurs.

  In the state where the slip occurs, the motor rotation speed is high and the rectangular wave control is performed. Moreover, since it slips, the load with respect to a motor is small and the motor actual electric current value is comparatively small. Then, by gripping, the motor rotation speed starts to decrease and the actual current value increases.

  When the actual current value (either Id0 or Iq0) exceeds the emergency switching threshold value (i), the mode is switched to the overmodulation mode at that time. As a result, the control mode shifts from the rectangular wave mode in which phase control is performed using a fixed rectangular wave to an overmodulation mode in which a voltage command is determined by current feedback.

  In this state, when the actual current value continues to increase and exceeds the emergency switching threshold value from overmodulation to PWM (when Iq0 becomes larger than the command value Iq * by a predetermined value), the control mode is changed to the PWM mode ( ii). At this time, a large change may occur in the voltage command (iii).

  This is because the current deviation is very large when the mode is shifted from the overmodulation mode to the PWM mode, and the voltage command in the PWM mode changes greatly with respect to the previous voltage command.

  In the square wave mode and overmodulation mode, the current feedback time constant is relatively large in order to maintain stable running. When a large change such as slip or grip occurs, the actual current is the target current. It is easy to shift from.

  Note that in overmodulation control, current detection is performed by interrupt control of the PWM carrier cycle, and the transition from the overmodulation mode to the PWM mode can also be determined in this cycle. However, the mode is changed at the cycle of the voltage command in order to prevent disturbance of the voltage command. For this reason, at the actual mode switching timing, the deviation between the actual current and the target current may be considerably large.

  And if this deviation is very large, the sign of the voltage command is reversed and the power running state is changed to the regenerative state.

The calculation of the voltage command in the PI calculation unit 26 is performed by the following calculation.
Vd = Kp (d-axis current deviation) + ΣKi (d-axis current deviation)
Vq = Kp (q-axis current deviation) + ΣKi (q-axis current deviation)

  Here, Vd and Vq are a d-axis voltage command, a q-axis voltage command, current deviations are (Id * −Id0) and (Iq * −Iq0), Kp is a proportional gain, and Ki is an integral gain.

  Here, in this embodiment, Kp> Ki is set in order to increase the responsiveness.

  Further, at the time of switching from the overmodulation mode to the PWM mode, the integral term is reset to a value corresponding to the voltage command at that time. That is, since the control mode is changed, the voltage command value immediately before switching is reset to improve the controllability of the PI control in the PWM mode after the change.

That is, the calculation of the first voltage command in the PWM mode is
Vd = Kp (d-axis current deviation) + Ki (d-axis current deviation) + previous Vd
Vq = Kp (q-axis current deviation) + Ki (q-axis current deviation) + previous Vq
It becomes.

  That is, as shown in FIG. 3, even if the immediately preceding voltage command is negative and the power running state is instructed, if the current deviation is large, the voltage command becomes positive in the feedback control in the PWM mode in order to reduce this current. It becomes a state.

  Therefore, in this embodiment, when the current deviation is large, the proportional gain is changed to a small value. That is, as shown in FIG. 4, the current deviation is compared with a threshold value (S1), and if the current deviation is larger than the threshold value, the proportional gain Kp is changed to a smaller value (S2).

  As a result, as shown in FIG. 5, the change to the last voltage vector in the overmodulation mode becomes relatively small, and it is possible to avoid the occurrence of a situation where the power running changes to regenerative.

For example, when the q-axis current command Iq * = − 20 A, the actual q-axis current Iq0 = −100 A, the previous voltage command Vq = −100000, Kp = 5000, Ki = 400, the voltage command Vq at the time of the PWM mode transition is
Vq = 5000 × (−20 − (− 100)) + 400 × (−20 − (− 100))
+ (− 100000) = 332000
Thus, the sign of the previous voltage command value minus 10000 is reversed.

On the other hand, if the threshold value for determining the current deviation as abnormal is set to 50 A, and Kp = 500 at that time is set,
Vq = 500 × (−20 − (− 100)) + 400 × (−20 − (− 100))
+ (− 100000) = − 2800
Thus, it is possible to prevent the sign of the voltage command from being inverted.

Here, in the above-described example, when the current deviation is equal to or greater than a predetermined value, the proportional gain is set to a predetermined small value. However, other techniques can be employed.
(I) The value of Kp when the current deviation exceeds the threshold value is not a fixed value, and a plurality of stages may be prepared according to the magnitude of the current deviation. Further, the decrease amount of Kp may be changed according to the threshold value and the magnitude of the current deviation at that time.
(Ii) When the current deviation is large, the voltage command may be prevented from being reversed from negative to positive instead of decreasing Kp. For example, when the sign of the voltage command obtained by calculation is reversed from the previous sign, the current command can be limited so that the sign is not reversed.
(Iii) When the current deviation exceeds the threshold value, the sign of the current command may be further prevented from being reversed.
(Iv) It is also preferable to apply a limit so that the q-axis voltage command does not change from negative to positive.

Furthermore, the following means can also be employed.
(I) In the rectangular wave mode and the overmodulation mode, the mode is immediately changed when it is detected that the current deviation exceeds a predetermined value. This makes it difficult for the current deviation to increase.
(Ii) Decrease the integral gain when shifting to the PWM mode. As a result, the response to the current deviation becomes dull, and a sudden control change can be prevented.

  10 DC power supply, 12 inverter, 14 motor, 20 ammeter, 22 UVW → dq conversion unit, 26 PI calculation unit, 28 current command generation unit, 30 dq → UVW conversion unit, 32 signal generation unit.

Claims (3)

A proportional term obtained by multiplying the current deviation by a proportional gain based on a current deviation that is a difference between a motor current command calculated based on a motor output torque command and an actual current measured by the motor; A motor control device that calculates an integral term obtained by multiplying an integral value of a current deviation by an integral gain, and calculates a supply voltage command to the motor based on the obtained proportional term and integral term,
As a motor control mode,
Overmodulation mode to obtain a motor current with a limit in a place with a large amplitude by PWM control,
PWM mode for obtaining a sinusoidal motor current by PWM control;
Have
The motor control apparatus characterized by changing the proportional gain small when the current deviation is large when shifting from the overmodulation control mode to the PWM control mode. The motor control device according to claim 1,
At the time of the mode transition, the integral term is reset to the voltage command value immediately before, and the integral term based on the current deviation is added to the reset integral term to calculate the present integral term. A motor control device. A proportional term obtained by multiplying the current deviation by a proportional gain based on a current deviation that is a difference between a motor current command calculated based on a motor output torque command and an actual current measured by the motor; A motor control device that calculates an integral term obtained by multiplying an integral value of a current deviation by an integral gain, and calculates a voltage command to the motor based on the obtained proportional term and integral term,
As a motor control mode,
Overmodulation mode to obtain a motor current with a limit by PWM control,
PWM mode for obtaining a sinusoidal motor current by PWM control;
Have
When shifting from the overmodulation control mode to the PWM control mode, when the sign of the calculated voltage command is reversed from the previous voltage command, the proportional gain is changed to be small so that the sign is not reversed. A motor control device.

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