JP2000135000A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the noise of a motor current detected value while maintaining the following of output. SOLUTION: The added value Iu+Iv+Iw of motor current values of each phase of an AC motor is computed with an adder 22, and this is compared with threshold value Ish in a comparator 24. Then, this motor controller judges that there is noise when the added value Iu+Iv+Iw is larger than the threshold value Ish, and filtrates the motor current detected value of each phase with a filter 26, and suppresses the change and removes noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling a drive current (motor current) of an AC motor, and more particularly, to a countermeasure against noise in a detected motor current value.

[0002]

2. Description of the Related Art Conventionally, AC motors have been used as various drive sources such as drive motors for electric vehicles. In this motor control device, first, an output torque command value is determined according to the accelerator opening and the like. Next, a motor current command value for each phase is determined based on the output torque command value. Then, the motor current value is detected, and the motor current is controlled so that the motor current value matches the command value.

[0003]

Here, the motor current value is detected by various current sensors, but the detected value may have noise depending on the state of the surrounding environment. . There is no problem when the noise is small, but when it is large, the motor current fluctuates greatly and the control becomes unstable. Therefore, it is conceivable to remove noise by applying a filter to the detected value to cut a large change in the detected value. However, when such processing is performed,
There is a problem that the ability to follow a change in the output torque command value is deteriorated.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a motor control device capable of achieving suitable noise removal while maintaining the ability to follow an output torque command.

[0005]

SUMMARY OF THE INVENTION The present invention provides a detecting means for detecting a motor current of each phase of an AC motor, an adding means for adding the detected motor current value of each phase, and an obtained motor current adding means. Comparing means for comparing the value with a preset threshold value, and filter means for performing a filtering process on the motor current detection value when the added value is larger than the threshold value in the comparison result. It is characterized by.

As described above, according to the present invention, since the sum of the motor currents of the respective phases becomes equal to or larger than the predetermined threshold value,
It is determined that noise is present. The added value of the motor current of each phase is usually 0, and the increased value makes it possible to effectively detect the presence of noise. Then, only when noise is present in the motor current detection value, the motor current detection value can be filtered by the filter, and the adverse effect due to the noise can be eliminated while maintaining the ability to follow the torque command. .

It is also preferable that the filter means performs a filtering process on a current command value for controlling a current to the motor when the added value is larger than a threshold value. In this way, by suppressing the change in the current command value, the adverse effect of noise can be eliminated as in the case described above.

[0008]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of a system using a motor control device of the present invention. An inverter 12 is connected to the battery 10. The inverter 12 converts DC power supplied from the battery 10 into a predetermined three-phase AC current. A motor 14 is connected to the inverter 12 and is driven according to the motor current supplied from the inverter 12.

The inverter 12 has, for example, six switching transistors, and supplies the motor current to the coil of one phase of the motor 14 by turning on two of them. Therefore, a three-phase motor current is supplied to the motor 14 by turning on two switching transistors in a predetermined order. The motor 14 is, for example, a drive motor of an electric vehicle, and the electric vehicle runs by driving the motor 14.

On the other hand, current sensors 16u, 16v, and 16w are provided in a current path from the inverter 12 to the motor 14, and motor currents Iu,
Iv and Iw are respectively detected. This current sensor 16
motor currents Iu, Iv, Iw of u, 16v, 16w are
It is supplied to the ECU 18. The ECU 18 controls the inverter 12 according to the torque command supplied from the outside and the detected value of the motor current of each phase to control the motor current of each phase. Note that the torque command is determined according to the accelerator opening, the detected value of the brake operation, and the like. The rotor position of the motor 14 is detected by a Hall element or the like, and is used for controlling the phase of the motor current. Furthermore, the Hall element may be omitted, and the rotor position may be detected from the detected value of the motor current.

FIG. 2 shows a functional block diagram of the ECU 18. The motor currents Iu, Iv, Iw of each phase detected by the current sensors 16u, 16v, 16w are input to the adder 22, where the added value Iu + Iv + Iw is calculated. The calculated sum Iu + Iv + Iw is calculated by the comparator 24
, Where it is compared with a preset threshold value Ish. It is preferable that the threshold value Ish be a value slightly larger than the fluctuation value during normal operation, for example, a value of about 5% of the maximum current value during normal driving of the motor.
The comparator 24 includes motor currents Iu, Iv,
A filter 26 to which Iw is supplied is connected, and the operation of the filter 26 is controlled by the comparison result of the comparator 24.

That is, the filter 26 filters the detected motor current value to reduce a sudden change in the detected value. In particular, the filter 26 filters the comparator 24 only when the added value Iu + Iv + Iw exceeds the threshold value, and does not normally perform the filtering.

The filtering in the filter 26 is as follows.
For example, according to the following equation.

[0015]

Iu (n) = Iu (n-1) + Kf−１Iu
(N) -Iu (n-1)} where Iu (n) is the current u-phase motor current detection value,
u (n-1) is the previous u-phase motor current detection value, and Kf is the filter gain. Note that the same processing is performed for the detected motor current values of the other phases. The filter gain Kf is
For example, it is set to a value of 1/16 or less.

By such filtering, the fluctuation of the motor current detection value can be suppressed within a predetermined range, and the adverse effect of noise can be prevented.

Here, such filtering is performed only when the sum Iu + Iv + Iw is larger than the threshold value Ish. In an AC motor 14 using a three-phase AC whose phases are shifted from each other by 120 °, the sum I
u + Iv + Iw is basically 0. This is not so large even in the transient state. Therefore, during normal operation, the added value Iu + Iv + Iw does not exceed the threshold value. On the other hand, when noise is present in the detected motor current value, the noise is less likely to be evenly distributed in the motor current of each phase, and the detected value of each phase varies greatly. In the present embodiment, the state where the noise is superimposed is detected by the comparator 24.

Therefore, the filter 26 can filter the motor current detection value only when the detection value is subject to noise as described above, and can maintain the ability to follow the torque command while adversely affecting the motor current. Can be eliminated.

The output value from the filter 26 is supplied to a three-phase / dq converter 30, where the excitation current component Id
Is converted into a torque current Iq. On the other hand, the torque command value T * created from the accelerator opening and the like is supplied to the current command value calculation unit 32. This current command value calculation unit 32
There is a map for the current command, and an exciting current command value Id * corresponding to the input torque command value T *,
A torque current command value Iq * is generated. Also, three-phase / dq
Excitation current component Id from converter 30, torque current Iq
Are supplied to adders 34d and 34q, respectively, where they are respectively added to the excitation current command value Id * and the torque current command value Iq * from the current command value calculation unit 32, and the excitation current command difference value ΔId and the torque current command The difference value ΔIq is calculated.

Then, the excitation current command difference value ΔId,
The switching in the inverter 12 is controlled according to the torque current command difference value ΔIq, and the motor drive current of each phase is controlled, so that the output torque control of the motor 14 according to the torque command T * is performed.

Next, FIG. 3 shows another embodiment, in which an exciting current command difference value ΔI
d, a filter 36 for filtering the torque current command difference value ΔIq. In the filter 36, the addition value Iu + Iv + Iw is calculated by the comparator 24 as the threshold value Is.
h, the following filtering is performed on the excitation current command difference value ΔId and the torque current command difference value ΔIq.

[0022]

ΔId (n) = ΔId (n−1) + Kfd ｛Δ
Id (n) −ΔId (n−1)｝ where ΔId (n) is the current excitation current command difference value, ΔI
d (n-1) is the previous excitation current command difference value, and Kfd is the filter gain of the filter 36. The same processing is performed for the torque current command difference value.

As described above, the filter 36 outputs the sum Iu
Only when + Iv + Iw exceeds the threshold value, filter processing for suppressing a change in the command difference value is performed. Therefore, similarly to the above-described embodiment, it is possible to effectively eliminate adverse effects due to noise.

FIG. 4 is a flowchart showing the operation of the ECU 18 described above. First, the current sensor 16u,
Motor currents Iu, Iv, I of each phase from 16v, 16w
w is fetched (S11). Next, these added values Iu +
It is determined whether Iv + Iw is smaller than a threshold value Ish (S12). If YES in this determination, it is determined that there is no noise in the motor current detection value, and normal processing is performed without performing filtering in the filters 26 and 36 (S1).
3). On the other hand, if the determination in S12 is NO, it is determined that noise has occurred in the detected motor current value, and the filters 26 and 36 perform filtering (S14).

As described above, according to the present invention, even if the detection values of the current sensors 16u, 16v, and 16w suddenly change due to noise, the current command value to the motor 14 does not suddenly change and stable control is performed. Can be.

Further, it is detected that noise is added to the detection value of the current sensor, and filtering is performed only when noise is added. Therefore, it is possible to prevent the following ability of the motor drive in a normal state including the transient state from being poor.

Further, in the position sensorless control for estimating the rotor position based on the motor current detection value without using a rotor position detection sensor such as a Hall element, the estimation of the rotor position is prevented from being disturbed by noise. be able to.

In the above-described example, the same filtering process is performed on the motor current detection value of each phase. However, the filtering may be performed only on the detection value of the phase with large fluctuation. It is also preferable to provide both the filter 26 and the filter 36 and to operate both filters when it is detected that noise has been added to the motor detection value. Further, the above-described processing can be similarly performed whether the output torque of the motor is positive (during power running of the electric vehicle) or negative (during regenerative braking of the electric vehicle).

In the above example, the threshold value Ish is
Although the value is fixed, it can be changed according to the change of the torque command T *. During steady running with little change in the torque command T *, the threshold value Ish is reduced,
At the time of acceleration / deceleration in which the torque command T * greatly changes, the threshold value Ish may be increased.

[0030]

As described above, according to the present invention,
When the sum of the motor currents of the respective phases becomes equal to or greater than a predetermined threshold value, it is detected that noise has occurred. Then, the filter is applied to the motor current detection value or the current command value only when noise is present on the motor current detection value. Thus, it is possible to eliminate the adverse effects of noise while maintaining the ability to follow the torque command.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a system including an apparatus according to an embodiment.

FIG. 2 is a functional block diagram showing a configuration example of a main part of an ECU 18.

FIG. 3 is a functional block diagram showing another configuration example of a main part of the ECU 18.

FIG. 4 is a flowchart showing the operation of the ECU 18.

[Explanation of symbols]

10 battery, 12 inverter, 14 motor, 1
6u, 16v, 16w current sensor, 18 ECU, 22
Adder, 24 comparator, 26, 36 filter, 30
Three-phase / dq converter, 32 current command value calculator.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eiji Yamada 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 5H115 PA03 PC06 PG04 PI16 PI29 PU11 PV09 PV23 QN03 QN09 QN21 RB26 TO12 5H576 AA15 BB05 BB09 CC04 DD02 DD07 EE01 GG04 HA02 HB01 JJ03 JJ08 JJ26 KK06 LL22 LL41

Claims (2)

[Claims] 1. A detecting means for detecting a motor current of each phase of an AC motor, an adding means for adding the detected motor current value of each phase, and an obtained motor current added value is preset. A motor control device, comprising: comparison means for comparing with a threshold value; and filter means for performing a filtering process on the motor current detection value when the addition value is larger than a threshold value in the comparison result. . 2. A detecting means for detecting a motor current of each phase of an AC motor, an adding means for adding the detected motor current value of each phase, and an obtained motor current added value is set in advance. Comparing means for comparing with a threshold value, and filtering means for filtering a current command value for controlling a current to the motor when the added value is larger than a threshold value in the comparison result. Characteristic motor control device.