JPH03218280A - Conduction polarity diagnosis unit for motor drive - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an apparatus for diagnosing an abnormality by monitoring the conductivity of an electric motor.

<Prior art> In recent years, in order to improve steering stability, some vehicles are equipped with an automatic stability control system that steers the rear wheels in the same direction as the front wheels when steering. 81
379 etc.).

In this model, the rear wheel steering was driven by hydraulic pressure,
It is necessary to route hydraulic piping, which poses a cost problem. Therefore, a system was proposed in which the rear wheels were steered using an electric motor.

The outline will be explained based on FIG. 5. The control unit 1 inputs the signals of the steering angle and vehicle speed of the front wheels 2, determines the target steering angle of the rear wheels 3, and uses the target steering angle and the electric motor 4.
A steering control signal is outputted to the motor drive circuit 5 according to the deviation from the actual steering angle of the rear wheels input manually. The motor drive circuit 5 drives the electric motor 4 according to the control signal,
The rear wheels are steered via the gear mechanism 6 until they match the target steering angle.

By the way, in the above method, electric motor 4? The steering direction of the rear wheels is changed by rotating forward or reverse. in this case,
If the rotational direction of the electric motor 4 cannot be controlled correctly, the direction in which the rear wheels are steered will be reversed, which may lead to an uncomfortable feeling when driving the vehicle.

For this reason, currently, as shown in FIG. 6, a polarity monitor is obtained by integrating the signal of one electrode terminal 0 of the electric motor 4 using an integrator 7, and comparing the integrated signal with the slice level using a comparator 8. A signal is output to diagnose an abnormality in the conduction polarity (rotation direction) of the electric motor, and fail-safe control is performed in which the electric motor 4 is de-energized in the event of an abnormality.

That is, when electricity is passed from the electrode terminal OI to the other electrode terminal 02 (in case 1 shown in the figure), the pulse of the duty signal output to the electrode terminal 01 is integrated, so that the integral value exceeds the slice level. Therefore, when a high-level monitor signal is output and the current is passed in the opposite direction (as shown in H
), the signal at the electrode terminal OI is maintained at a low level, so the integral value is below the slice level and the polarity monitor signal is maintained at a low level. The level of the polarity monitor signal is compared with the polarity command value (included in the target steering angle) from the control unit 1, and if the levels match, it is determined to be normal, and if they do not match, it is determined to be abnormal (7th
(see figure).

Problems to be Solved by the Invention However, as shown in FIG. 8, in this conventional abnormality diagnosis method, a polarity failure occurs when the electric motor 4 is stopped (current command signal is at a low level). However, abnormality determination cannot be made until the electric motor 4 is energized and begins to rotate. Then, there is a delay until the integral value of the duty signal pulse exceeds the slice level after the polarity command signal is reversed until the polarity monitor signal is reversed. Since the delay time is prolonged, it is necessary to delay the determination time.

Therefore, even if the electric motor is stopped immediately after the electric motor polarity (rotation direction) is determined to be abnormal, the electric motor may be reversed before the determination is made.
Although this does not affect the driving sensation at low speeds, it may cause an uncomfortable feeling when driving at high speeds.

The present invention has been made in view of such conventional problems, and provides an electric motor drive device in which an abnormality in conduction polarity is determined without starting the electric motor during stop control of the electric motor. The purpose is to provide an abnormality diagnosis device.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the abnormality diagnosis device for an electric motor drive device according to the present invention makes the polarity of the electric motor variable based on a polarity command signal and a current command signal. In a drive device that is driven by electricity, when controlling the stop of the electric motor,
Signal level control means for outputting a current command signal at a low level such that the electric motor cannot start, and outputting a polarity command signal with the level inverted at a high frequency, and a signal level control means for monitoring and forming a signal at an electrode terminal of the electric motor. polarity monitoring means for outputting a polarity monitor signal, and abnormality determination means for determining an abnormality in conducting polarity by comparing the polarity command signal whose level is inverted at a high frequency and the polarity monitor signal. did.

Function> The signal level control means outputs the current command signal at a low level that makes it impossible to start the electric motor when power to the electric motor is stopped, and inverts the level of the polarity command signal at a high frequency. Output.

On the other hand, the polarity monitor means monitors the signal of the electrode terminal of the electric motor to form a polarity monitor signal, and outputs the signal.

The abnormality determining means compares the polarity command signal whose level is inverted at the high frequency with the polarity monitor signal to determine whether the conduction polarity is abnormal.

Example Embodiments of the present invention will be described below based on the drawings.

In FIG. 1 showing the configuration of an embodiment applied to an automatic stability control system similar to the conventional example, the control unit 11 includes various controllers (not shown) installed in the vehicle. Front wheel steering angle signal, rear wheel steering angle signal, vehicle speed signal detected by the sensor,
The engine rotation speed is set to O, and the automatic stability control system is activated.
N. The signal from the OFF shift switch (SW) and the electric motor polarity monitor signal are input.

The control units 1 to 1 to 11 calculate the target steering angle of the rear wheels based on the input signal using a built-in microcomputer, and output a polarity command signal for the electric motor 12 according to the input signal to the FET bridge drive circuit 13. At the same time, a current command signal is output to the PWM control circuit 14. Further, the polarity command signal and the polarity monitor signal are compared to diagnose an abnormality in the conduction polarity, and in the event of an abnormality where the polarity of the command value and the monitor value do not match, fail-safe control is performed to stop the electric motor 12. conduct.

Electrode terminal 0 of electric motor 12. , 0■, respectively, power supply■
8 via switches S1 and S2, and grounded via switches S3 and S4 and a current monitoring resistor r.

The switch S1 and the switch S4 are the FE
connected to the output terminal D of the T bridge drive circuit 13;
It turns ON when the output level of the output terminal D1 is high,
The switch S2 and the switch S3 are connected to the output terminal D2 of the FET bridge drive circuit 13, and are set to be turned on when the output level of the output terminal D2 is high.

The PWM control circuit 14 includes the current monitoring resistor r
A current monitor signal from a current monitor circuit 15 connected between the terminals of the control unit 1 and 1 is inputted to the control unit 1.
The FET bridge drive circuit 13 sets the duty ratio of the duty signal output to the electric motor 12 while comparing the motor current command signal and the current monitor signal from 1.
Output to.

Further, the signal from the one electrode terminal Ol is inputted to the sensor 1 terminal S of the flip-flop 16, and the signal from the other electrode terminal 02 is inputted to the positive terminal R of the flip-flop 16. The flip-flop 16 outputs a polarity monitor signal that becomes high level when triggered by the pulse of the duty signal input through the electrode terminal 01, and becomes low level when triggered by the pulse of the depth signal input through the electrode terminal 02. do. Immediately,
Flip-flop 16 constitutes polarity monitoring means.

The polarity monitor signal is input to the control unit 11, and as described above, the control unit 11 compares the polarity command signal and the polarity monitor signal to perform abnormality diagnosis of conduction polarity and fail-safe control. .

FIG. 4 shows a routine for energization control (including abnormality diagnosis of energization polarity and fail-safe control) for the electric motors in the control units 1 and 11.

In the figure, in step 1 (denoted as S in the figure), an electric motor 1 is operated according to rear wheel steering control based on various detection signals.
2. Set the levels of the polarity command signal and current command signal.

In step 2, it is determined based on the current command signal set in step 1 whether or not the electric motor 12 is under stop control.

When it is determined that the electric motor 12 is under stop control, the process advances to step 3 and the level of the current command 9 signal is set to a low level that makes it impossible to start the electric motor 12, as shown in FIG. At the same time as setting and outputting, the level of the polarity command signal is changed to a high frequency (for example, I
KHz) and output it.

That is, the function of step 2.3 corresponds to the signal level control means.

In step 4, the level of the polarity command signal oscillated in step 3 is compared with the level of the polarity monitor signal input from the flip-flop 16.

Then, when the levels of both signals match, that is, when it is determined that the conduction polarities match, it is normal, so proceed to step 5, reset the NG flag to O,
Complete this routine.

If it is determined in step 4 that the levels of the two signals do not match, it is diagnosed that the conduction polarity is abnormal, and the process proceeds to step 6, where the NG flag is set to 1 and this routine ends. That is, the functions of the steps 4 to 6 correspond to the abnormality determining means in the present invention.

10 On the other hand, if the electric motor 12 is commanded to be energized in step 2, the process advances to step 7 and an NG flag is determined.

When the NG flag is -1, the process proceeds to step 8, where the current command signal is set to 0 level. As a result, power supply to the electric motor 12 is forcibly stopped.

If the NG flag is 10, the process proceeds to step 9, where the levels of the polarity command signal and the polarity monitor signal are compared after a short time (pulse width of the duty signal) has elapsed since the polarity command signal was inverted.

If the polarities match, it is normal, and the process proceeds to step 10, where the polarity command signal and current command signal set in step 1 are output; however, if they do not match, it is abnormal, and the process proceeds to step 6. sets the NG flag to 1 and ends this routine.

According to such control, an abnormality diagnosis can be performed while the electric motor 12 is stopped, and since the configuration is configured to forcibly stop energization when an abnormality occurs, it is possible to avoid reverse rotation of the electric motor 12. Incidentally, an abnormality that occurs while the electric moke 12 is energized is also diagnosed, and when an abnormality occurs, the energization is immediately stopped. In addition, as in this embodiment, by using the flip-flop 16 as the polarity monitoring means, the polarity monitor signal can quickly follow the polarity command signal whose level is inverted at a high frequency when the motor is stopped, and the polarity comparison can be performed. Moreover, since the polarity monitor signal is triggered by the first pulse immediately after the polarity command signal is inverted without integrating the duty signal even during energization, abnormality determination can be performed with almost no delay.

Furthermore, although this embodiment has been applied to an automatic stability control system, it can also be applied to cases where an electric motor is used in a power steering drive device with a similar drive mechanism. Application is not limited to motors, but can also be applied to linear motor drive devices.

<Effects of the Invention> As described above, according to the present invention, malfunctions of the electric motor can be prevented by 12 times since abnormalities in the conductivity of the electric motor can be determined from the time the electric motor is stopped.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a diagram showing a hardware configuration of an embodiment of the present invention, and FIG. 3 is a flowchart showing a control routine in the same embodiment.
Figure 4 is a diagram showing the state of each part under the same control;
The figure is a plan view showing an outline of a conventional autopilot stabilization system, FIG. 6 is a circuit diagram showing one side of the rotation direction monitor of the electric motor drive device in the same device, and FIG. 7 is each part of the one-side monitor type. FIG. 8 is a time chart showing the state of each part when an abnormality occurs in the one-side monitor system.

Claims (1)

[Claims] In a drive device that energizes and drives an electric motor with variable polarity based on a polarity command signal and a current command signal, when controlling the electric motor to stop, outputs a current command signal at a low level that prevents the electric motor from starting. a signal level control means for inverting the level of the polarity command signal at a high frequency and outputting the polarity command signal; a polarity monitoring means for outputting a polarity monitor signal formed by monitoring a signal at an electrode terminal of the electric motor; An apparatus for diagnosing conduction polarity of an electric motor drive device, comprising: an abnormality determining means for determining an abnormality in conduction polarity by comparing a polarity command signal whose level is inverted and the polarity monitor signal. .