JPS61240882A - Safety device for brushless motor - Google Patents

Abstract

PURPOSE:To effectively detect the abnormal rotation by detecting the malfunction when information of position change is not obtained by position detecting means for detecting the positional relation between a rotor and a stator irrespective of the executed rotating process. CONSTITUTION:Position detecting signals SW1-SW3 from position detecting means for detecting the positional relation between a stator and a rotor are input to a microcomputer 6. The microcomputer 6 outputs a drive signal to transistors Q1-Q3 on the basis of the inputs of the signals SW1-SW3 to rotate a motor. When the signals SW1-SW3 are not obtained even if a drive signal is output, the microcomputer 6 judges that the motor or a load is abnormal to all turn OFF the drive signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a safety device for a brushless electric motor, and more particularly to a safety device that reliably detects abnormal rotation of an electric motor.

[Background of the invention]

As a method for protecting against abnormal rotation of an electric motor, there is a method described in, for example, Japanese Patent Laid-Open No. 106896/1983.

This protection method detects abnormal rotation of the brushless motor.

However, this protection method only detects rotational abnormalities when the motor is started.

[Purpose of the invention]

An object of the present invention is to provide a safety device that reliably detects abnormal rotation of a brushless electric motor.

[Summary of the invention]

In order to achieve the above object, the present invention uses a position detecting means that is provided in a brushless electric motor and detects the positional relationship between a rotor and a stator. If no position change information is obtained, an abnormality is detected and the rotation process of the motor is stopped.

[Embodiments of the invention]

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

FIG. 4 is a sectional view showing the structure of a brushless electric motor to which an embodiment of the present invention is applied. In the figure, reference numeral IVi housing, a two-piece end bracket, 3 a fixed magnetized rotor, 4 a stator, a stator winding provided on a 5Fi stator, and 6 a position detection means. The rotor 3 can be rotated by detecting the magnetic poles of the rotor 3 by the position detecting means 7 and sequentially switching the current flowing through the stator winding 5 provided on the stator 4. FIG. 1J/II1 is a circuit diagram showing a safety device according to the present invention. In the figure, SW1-8W3 are position detection signals, and the detection signals SW1-SW3 are given from a position detection means 7 provided in the brushless motor. The position detection means 7 detects the positional relationship between the rotor 3 and the stator 4 and outputs position detection signals 5WI-8W.
Outputs 3. Each of the windings Q1 to Q3 of the stator winding 5 provided on the stator 3 is the stator winding 5a to 5C.
R1-R3 are resistors connected to the bases of the transistors Q1-Q3, DQI-DQ3
Reference numeral 6 indicates a drive signal for driving the transistors Q1 to Q3, and 6 indicates a microcomputer that controls drive signals DQI to DQ3 based on the input of the position detection signals sw1 to SW3. Outputs the microcomputer DQ3 and rotates the electric motor. When the motor is rotating normally, VC outputs drive signals DQI to D based on the input of position detection signals SWI to SW3.
By outputting Q3, position detection signals SWI to SW3 can be obtained in sequence.

However, for some reason, the load on the stain motor or electric motor may be in an abnormal state, and a situation may occur in which the position detection signals sw1 to SW3 are not obtained even though the drive signals DQI to DQ3 are output. Therefore, when each position detection signal is obtained, a timer is activated for a certain period of time. For example, when this timer is activated by the position detection signal SWI, it is reset by the next position detection signal SW2. The timer activated by the position detection signal SWI is the timer TI, and the timer activated by the position detection signal SW2 is the timer T2. It is assumed that the timer activated by the position detection signal SW3 is a timer T3. Therefore, timer T1 is started by position detection signal SWI and reset by position detection signal SW2, timer T2 is started by position detection signal SW2 and reset by position detection signal 8W3, and timer T3 is started by position detection signal SW3. , and will be reset by the position detection signal SWI.

Now, if the position detection signal SW3 is not obtained even though the drive signal DQ2 is output, the drive signal DQ2
When the set time of timer T2, which started at the same time as the output of Enters abnormality processing to stop rotation control. The set time of the timer T is set to be longer than the set minimum rotation speed of the motor, and is set to a time that will not cause burnout of the circuit and the motor even if the motor is locked. This setting time is usually
It takes a few seconds. Furthermore, this safety processing can detect not only abnormal conditions in the motor but also abnormalities in the circuit. For example, there is a case where the fixed hand winding 5a['[ current does not flow even though the transistor Q1 is damaged and the drive signal DQI is output.

Furthermore, if the electric motor is equipped with a brake, the brake may be actuated to stop the electric motor.

FIG. 2 is a time chart showing the operation described above. The figure shows that when the electric motor is rotating at a constant rotation speed,
This is based on the assumption that the position detection signal SW3 is no longer obtained, and time t is the time at which it is determined that the abnormal state is present. In the figure, the portion indicated by a broken line is a time chart during normal operation.

FIG. 3 is a flowchart showing the processing operation of the microcomputer 6 in the operation described above. 1' when position detection signal 8W1 is on and position detection signal 8W2 is off
(Step 100), reset the timer T3 (Step 101), turn on the drive signal DQI and turn on the DQ2
．． DQ3 off Step 102) Stator winding 5aVc
[To communicate with the flow. Further, a timer 1t is set and activated (steps 103 and 104). Drive signal DQI
When the position detection signal SW2 is turned on and switched from OFF to ON, the drive signal is also switched from DQI to DQ2, and the stain machine continues to rotate (when the determination in step 105 is NO). However, the position detection signal 8 from when the drive signal DQI is turned on until the set time of the timer 1 has elapsed
If W2 is not switched from on to off (step 105)
When the determination is YES in Step 1), it is considered to be an abnormal state and abnormality processing is performed to stop the rotation of the electric motor (step 1).
06).

Note that if it is determined in step 100 that SWI is on and 8W2 is off, and the determination is NO, step 10
7, where it is determined whether SW2 is on and SW3 is on. If the determination in step 107 is YES, steps 108 to 112 are executed, and the content of the processing is almost the same as steps 101 to 105, except that the object to be controlled is different. If the determination in step 107 is NO, the process moves to step 113.
If YES is determined in step 113, step 11
4 to step 118 will be performed.

In this way, certain processing will be performed.

〔Effect of the invention〕

As described above, according to the present invention, a signal from a position detection means for detecting the positional relationship between a stator and a rotor, which is provided in advance in a brushless motor, is taken in, and rotation abnormality is detected based on the signal. Since the timer is driven and reset, it is possible to detect not only abnormal rotation of the motor but also abnormalities in the load or circuit driven by the motor. . Further, according to the present invention, since a pre-installed position detection means is used, there is no need to install a new detection means for safety, which is economical.
Another advantage is that the structure of the electric motor does not become complicated.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the safety device according to the present invention,
FIG. 2 is a time chart showing the operation of the same embodiment, FIG. 3 is a flow chart showing the operation of the microcomputer,
FIG. 4 is a sectional view showing the structure of a brushless electric motor. swi~SW3... rank f! ! @ Output signal, Q1~Q3・
...Transistor, R1~R,3...Resistance, DQI~
DQ3... Drive signal, l... Housing, 2...
End bracket, 3... rotor, 4... stator,
5, 5a, 5b. 5C... Stator winding, 6... Position detection means, 7...
・Microcomputer.

Claims (1)

[Claims] 1. A stator comprising a fixed magnetized rotor, a multiphase stator winding group that generates a magnetic field to give rotational force to the rotor, and a current flowing through the multiphase stator winding group. In a brushless electric motor configured to include current control means for sequentially switching the rotor and position detection means for detecting the positional relationship between the rotor and the stator, the current control means causes the current to flow. A timer is provided which is activated when the phase is switched and is reset by a detected position signal obtained by the position detecting means, and when the timer detects that the detected position signal has not been switched, the current control means is activated. A safety device for a brushless electric motor, characterized in that the control is stopped.