JPS5999991A - Runaway detector for dc motor - Google Patents

Abstract

PURPOSE:To enable to effectively detect the malfunction of a DC motor by comparing the rotating speed of the motor with a reference signal by detecting the speed on the basis of measured motor terminal voltage, motor armature circuit current and motor pole magnetic fluxes. CONSTITUTION:Values measured by a motor field current detector 5, a motor armature current detector 6 and a motor terminal voltage detector 7 are inputted to an operational amplifier 8, and the rotating speed N as the approximate value of the actual rotating speed is calculated. The calculated rotating speed N is inputted to a comparator 10 through an absolute value circuit 9. Here, it is compared with a rotating speed signal 10-b of the predetermined reference, and a runaway detection signal 10-c is outputted when the rotating speed N is larger than the reference rotating speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting lh flow motor runaway.

DC motors may cause failure of the motor control device,
In the case of tacho generator feedback control, tacho generator failure, tacho generator polarity reverse connection, feedback circuit failure, etc. may occur, and as a result,
Speed feedback signal disappears. +1 If an abnormally high voltage is applied to the DC motor due to the above reasons, the motor may run out of control at an abnormal speed, which is extremely dangerous. Conventionally, as a means of detecting in advance that a DC motor would run out of control for reasons such as those described in the future, the terminal voltage ratio of the motor was monitored, and if the level exceeded a predetermined reference value, an abnormality signal was sent. A device has been used to release but,
When using this device, even if the motor is operating normally, high voltage is applied when the motor is accelerating, so the disadvantage is that it may become impossible to distinguish between normal and runaway after an hour of outputting the runaway detection signal. there were.

This invention was made in view of the above points and to eliminate the above-mentioned drawbacks.The invention detects the rotational speed of the motor based on the measurement of the voltage at one terminal of the motor, the current in the circuit of the motor electric machine, and the magnetic flux of the motor magnetic poles. Then, compare this detection signal with a predetermined reference value.

If the actual rotation speed exceeds the predetermined standard,
This was an attempt to distinguish between normal operation and runaway by using a device that issued a runaway signal.

The present invention will be described in detail below based on the drawings.

DC motors include series-wound motors and shunt-wound motors.

There are several types, such as page 3, but in this embodiment, a runaway detection device according to the present invention using a shunt motor will be explained.

1 in FIG. 1 is a shunt motor, which is composed of a field coil 2 and an armature 3, which are the components of the shunt motor.
Therefore, it is connected to the drive device 4 via the motor field current detector 5 and the motor armature current detector 6. '7 is a voltage and pressure detector at one end of the motor, which is connected in parallel between the two-stage shunt motor 1 and the motor 1 driving device 4 shown in -.

FIG. 2 is a block diagram of a DC motor runaway detection device according to the present invention. 8 is an operational amplifier, 8-a is the input of the signal from the motor field current detector 5, and 8-1] is the input of the signal from the motor electric current detector 6 (8-power,
8-c is the manual signal from the motor one terminal voltage detector 7. 9 is an insulation value circuit, 10 is a comparator, 10-a is an input of the signal from the absolute value circuit 9, 10-b is a manual input of the rotation speed that is a predetermined reference, and 10-c is an L comparator. This is the output of the signal from 10.

- In the configuration shown in FIG. 1, the motor field current detector, motor electric current detector 6, and motor terminal voltage detector 7 are connected to the operational amplifier 8Vc in FIG. 2, respectively. Then, the following formula is used to calculate the rotation speed lV, which is the latest value of the actual rotation speed.
I seek.

motor armature current and α, motor armature resistance φ; magnetic flux of motor magnetic pole) (,, l<λ; proportionality constant Note that the proportionality constant 2 and motor armature resistance are predetermined, and , in the range where the magnetic path is not saturated, φ
[It can be considered Eto. The rotation speed N divided by the above is inputted to the comparator 10 through the absolute value circuit 9. Here, a predetermined standard rotational speed signal 10
−b, if the above rotational speed N is lower than the reference rotational speed
If is large, a runaway detection signal 10-0 will be output.In addition, the rotation speed N may be ignored because the plan voltage and pressure are ignored, and the actual resistance of one motor armature may change depending on the temperature. For some reason, tq is determined as an approximation of the actual rotation speed (T), but since the purpose of the present invention is to detect abnormalities, there is no need to obtain a precise rotation speed, and the error occurring in the above rotation speed N is is not a problem in the present invention. Although this embodiment has been described using a shunt motor among DC motors as an example, other DC motors can be implemented with a similar configuration.

According to the method described in the embodiment, even if the voltage at one terminal of the motor is high, it is possible to obtain a rotation speed approximate to the actual rotation speed, and the rotation speed according to the above embodiment can be calculated. By comparing the number of rotations with a predetermined standard rotation speed, it is possible to detect abnormalities in DC motors more reliably than before, and it is possible to detect runaway in advance in any case. There is.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram of a DC motor and various detectors according to the 11th embodiment, and FIG. 2 is a block diagram of a DC motor runaway detection device in this embodiment. Page 6 8... Exercise amplifier 10... Comparator applicant Shinko Electric Co., Ltd. agent Patent attorney Haruya Saito

Claims (1)

[Claims] A practice amplifier that calculates the rotation speed from one terminal voltage of a DC motor, a motor armature current, and a motor field current, a rotation speed signal from the above-mentioned practice amplifier, and a rotation speed signal that serves as a predetermined reference. A DC motor runaway detection device that uses a comparator to compare and obtain a motor runaway detection signal.