SU845227A1 - Method of testing commutator electric motor sliding contact - Google Patents

Description

(54) METHOD FOR CONTROLLING A MOVING CONTACT OF A COLLECTOR MOTOR

one

The invention relates to the field of electric machines and is intended for use in the course of operation, in particular for an in-place determination of the technical condition of the sliding contact of an electric motor.

A known method of controlling a sliding contact of a collector electric motor based on an estimate of the voltage drop across the sliding contact, the variable component of the voltage drop 1 being used as a parameter. The disadvantage of this method is the low accuracy of the diagnosis.

There is also known a method for controlling a sliding contact of a collector electric motor based on estimating mechanical defects by parameters of switching pulsations of voltages at a fixed rotation frequency and direct current, generating a controlled signal and estimating the condition of a sliding contact by the deviation of the specified signal from the setpoint signal 2.20

Transient voltage drop depends on a large number of uncontrollable factors, namely: pressure between the contacting elements, composition of the brush material, contact temperature, pressure and humidity of the environment, etc. Any change in the transient voltage drop caused by deviations of uncontrollable factors from the corresponding values, at which the reference value of the voltage drop is determined, will be perceived as a change in the technical condition of the engine and, consequently, will lead to a decrease in the accuracy STI control. The purpose of the invention is to improve accuracy.

To achieve this goal, the measurements are repeated at a different frequency of rotation, and the monitored signal is formed as the ratio of switching voltage pulsations at two frequencies of rotation.

Claims (2)

Since the influence of mechanical defects of the sliding contact on the value of the transient voltage drop in it increases with increasing rotation frequency, the presence of such defects will lead to an increase in voltage transient at the maximum rotation frequency more than the minimum for given rotational frequencies and constant current consumption. Therefore, with the occurrence of sliding contact defects, the magnitude of the ratio of transient voltage drops at fixed rotational frequencies will increase to a greater extent than the value of a similar ratio for a sliding contact that does not have mechanical defects. Since uncontrollable parameters equally affect the change in switching pulsations on stresses both at minimum and maximum rotational frequencies, at a constant value of the electric motor current their ratio does not depend on the uncontrolled parameters, and therefore the controlled signal equal to this ratio, carries information only about the mex x defects of the slip contact, which leads to an increase in the accuracy of control. The reference signal is also formed as the ratio of the switching voltage pulsations at the same rotational frequencies, for the same type of electric motor, but without defects. As the maximum rotational speed, it is advisable to choose the maximum possible rotational speed according to the technical conditions for this motor. The choice of the minimum rotational speed is based on the possibilities of measuring it with the required degree of accuracy. The elimination of the influence of uncontrolled parameters makes it possible to increase the accuracy of control. Claims The method of controlling the sliding contact of a collector electric motor based on the evaluation of mechanical defects by the parameters of switching ripple voltages at a fixed rotation frequency and direct current, the formation of a controlled signal and the evaluation of the state of the sliding contact by the deviation of the specified signal from the setpoint signal, differing from that, in order to increase accuracy, repeat the measurement k) t at a different rotation frequency, and the monitored signal is formed as the ratio of switching stress variations at two frequencies of rotation. Sources of information taken into account during the examination 1. USSR author's certificate No. 60950, 1940, H 02 K 15/00. 2. USSR author's certificate in application number 2458951/24 07, 1977, H 02 K 15/00.