JP2001161089A - Control device for polyphase motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect malfunction in the Hall element of a brushless DC motor with a simple structure. SOLUTION: The output signals (a), (b), (c) of Hall elements 18-1, 18-2, 18-3 are inputted into an MPU22. The MPU22 calculates the respective frequencies of the output signals (a), (b), (c) and compares them. If the output signals are substantially equal to each other, it is taken as no malfunction. On the other hand, if the three frequencies are not equal, it is considered as malfunction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a polyphase motor, and more particularly, to a failure detection of a phase detecting means for outputting a signal corresponding to a phase of a rotor of the motor.

[0002]

2. Description of the Related Art In a three-phase brushless DC motor or the like, a configuration is known in which a Hall element is arranged for each phase on a stator side in order to detect a phase of a rotor. With this Hall element, the passage of the permanent magnet of the rotor is detected, and the phase of the rotor is calculated.

[0003]

If the above-mentioned Hall element breaks down, it becomes impossible to perform desired control on the electric motor. For example, if one of the three Hall elements fails, the frequency of the signal output from the Hall element becomes ／. On the control device side, the rotation speed of the motor is 2 /
It is determined that the speed has become 3, and control is performed to increase the speed to a predetermined speed. Therefore, the actual speed is 1.5 times the expected speed.
It will be doubled.

SUMMARY OF THE INVENTION The present invention has been made in order to accurately catch a failure of a phase detecting means (for example, a Hall element) which causes an operation at an abnormal speed or the like. I do.

[0005]

In order to achieve the above object, a control device for a polyphase motor according to the present invention is arranged for each phase and outputs a signal corresponding to the phase of a rotor of the motor. Detecting means, the frequency of the output of the phase detecting means, frequency calculating means to calculate for each phase detecting means, monitoring whether the frequency of each of the phase detecting means is substantially equal, if not equal, Failure determination means for determining a failure of the phase detection means. In particular, the phase detection means and the signal are used for controlling the supply power for each phase of the motor.

According to this configuration, the phase detecting means is an existing one for driving, that is, for detecting the phase of the rotor in controlling the supply power of each phase. There is no need to provide the motor. Further, the phase detecting means may be a Hall element for detecting whether or not the permanent magnet of the rotor is at a position facing the detecting means.

[0007] Further, it is possible to have a notifying means for notifying of a failure based on the failure determination.

[0008]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. Electric motor 1
Reference numeral 0 denotes a three-phase brushless DC motor.
And receives power supply from the motor driver 14 for rotation. Three Hall elements 18 are arranged on the stator side as phase detecting means for detecting the phase of the rotor 16. If it is necessary to distinguish these Hall elements from one another,
Description will be made using reference numerals 18-1, 18-2, and 18-3. A three-phase coil 20 is arranged on the stator side. The signals a, b and c from the Hall elements 18-1, 18-2 and 18-3 are shown in FIG.
Is a square wave signal that repeats high level and low level as shown in FIG. The output signals a, b, and c of the Hall element 18 are sent to the motor driver 14, and power corresponding to the phase indicated by the output signal is supplied to the coils 20 of each phase. Motor driver 1
4 is connected to a speed setting device 26 provided outside.
The setting device 26 sets the rotation speed of the electric motor 10. The motor driver 14 supplies electric power to the coils of each phase so as to achieve the set speed.

The output signal of the Hall element 18 is
(Microprocessor unit) 22 where various calculations are performed. The MPU 22 is connected to a higher-level control device 24 such as a computer, from which various commands are supplied. In the present embodiment, the MPU 22 outputs the output signals a, b,
Each frequency of c is calculated. Further, the frequencies are compared to monitor whether these three frequencies are substantially equal. Hall element 18 and MPU
If there is no abnormality in the conductor connecting 22, three Hall elements 1
8 output signals having the same frequency. Conversely, if any one is abnormal, the frequency of the output signal of this element has a value different from the others. For example, when the conductor connected to one Hall element 18-1 is broken, the output signal a is not sent to the MPU 22. In the MPU 22, the frequency is calculated as 0 because the output signal a does not change.
However, since the other output signals b and c are calculated as normal values, the values of the three output signals are not equal. Thus, it can be determined that a failure has occurred in at least one Hall element 18. If the two Hall elements 18 fail during the operation of the motor, the remaining one shows a normal value, so that the failure can be found in this case as well. Further, when the motor is started when the two Hall elements 18 are out of order, there is a case where the rotation is started or a case where the motor is stopped because of the difference in the stop position. If the motor rotates, the output frequencies of the three Hall elements 18 do not become equal as described above, so that a failure determination is made based on this. When the motor is stopped without rotating, the output frequency of the Hall element 18 is 0 even though the drive control is being performed. Three
When a failure occurs in each of the Hall elements 18, the output frequencies of all the elements become 0 even though the drive control is being performed, so that the failure can be determined based on this.

When such a situation occurs, the MPU 22
Determines the failure of the Hall element 18. Based on the failure determination, the upper control device 24 instructs the alarm device 28 to notify the failure of the Hall element 18. As described above, in the present embodiment, since the abnormality determination is performed based on the output of the Hall element used for drive control, there is no need to add a new configuration, and the motor does not increase in size.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of the present embodiment.

FIG. 2 is a diagram showing a waveform of an output signal of a Hall element 18;

[Explanation of symbols]

10 motor, 12 control device, 14 motor driver, 16 rotor, 18 Hall element (phase detection means),
22 MPU (frequency calculating means, failure determining means), 28
Alarm device.

Claims (3)

[Claims] 1. A control device for a multi-phase motor, comprising: phase detection means arranged for each phase and outputting a signal corresponding to a phase of a rotor of the motor, wherein the signal is provided for each phase of the motor. Phase detection means, which is provided for controlling the supplied power, frequency calculation means for calculating the frequency of the output of the phase detection means for each phase detection means, and the frequency of each of the phase detection means is substantially And a failure judging means for judging a failure of the phase detecting means when the two are not equal. 2. The control device for a polyphase motor according to claim 1, wherein said phase detection means is a Hall element for detecting the presence or absence of a permanent magnet of a rotor. 3. The control device for a multi-phase motor according to claim 1, further comprising: a notifying unit for notifying a failure based on the failure determination.