SU920941A1 - Device for protecting dc motor from overload - Google Patents

Description

The invention is developed in electrical engineering and can be used in automatic control and regulation systems with current-drive thyristor drives.

A device for controlling an electric motor, comprising an excitation regulator, is known; the unit is comparable to. neither, current sensor, excitation and current sensor core, dividing unit, two limiting units f.

The drawback of the device is to operate at a constant current in a linear mode, which leads to a significant generation of heat at the output stages.

The closest in technical terms to this invention is the known device for limiting the current in a reverse electric drive constant current containing a controllable converter, a motor core current sensor, a threshold unit, a voltage divider, a valve bridge, a key element 2.

The disadvantage of this device is the necessity of matching the output parameters of the current sensor with the input parameters of the electronic part of the device, which leads to a considerable complication of the electronic part of the device. In addition, in most cases, by the conditions of application, it is not possible to directly potentialally connect the output of the current sensor to the input of the amplifier, therefore, as a rule, various isolating devices are used. All this leads to device complexity.

10 and reduce the reliability of his work,

. The purpose of the invention is to increase the reliability of the device.

This goal is achieved by the fact that the device for protection of electro 15. DC motor overload, containing a controlled inverter, supplying a DC motor, made in the form of serially connected

Claims (1)

20 of the control pulse shaping unit, the first input of which is connected to the input source, the thyristor rectifier, the output of the latter is connected to the electric motor of the DC motor, the threshold unit, the first input of which is connected to the voltage source, the output to the second the input of the control pulse shaping unit of the converter, the series-connected band-pass filter and the detector are additionally introduced, and the input of the band-pass filter is connected to the output of the thyristor top of the transducer zovatel, .a detector output - to the second input of the threshold unit. The drawing shows a functional scheme of the device. Device To protect the DC motor from overload, it contains a controlled converter 1, WELL filled as a series of connected blocks 2, a control cadmium pulse and a thyristor Rectifier 3, the output of the latter is connected to a DC motor, 4 and through serially connected bandpass, filter 5 and detector b to the second input of the threshold unit 7, the first input of which is connected to the voltage source Ugp, and the output to the second input of the control pulse shaping unit 2 in the converter 1, the first input of the latter is connected to the input source Ug, x. The operation of the device is based on the use of nonlinear properties of a thyristor rectifier system - electro YaViha tel 11, in which the first iPapMOHH control signal is uniquely determined by the electric motor core, the input signal and. | (... enters) pulses (Ui) to control the angle of opening of the thyristors in the thyristor rectifier 3, feeding the alternating current voltage. The output signal of the rectifier 3 is the control signal for the electric motor of constant current voltage 4 and is supplied only the motor 4 but also the bandpass filter 5, which is tuned to the first harmonic of the control signal. The signal from output 5 to the rain filter goes to a damper b, which highlights the envelope of the first harmonic, and the signal from its output Ufe is compared in a threshold block 7 by a signal from the reference voltage reference Ugp at Ue, and or, Uorp О At Ofe f, Don Ufp; i О, where Dorp is the signal of the current of the motor core when exceeded by a signal from the detector output b from the source of the reference voltage and to the second input of the B. block 2 formation control respectively having a pulse output from the threshold unit 7 receives the signal .With You are a controlled stroke by the converter 1 on the DC motor 4 receives control signal limiting effect formed nepbsredstvenno of the motor control signal, wherein, isolating its first harmonic. The present invention improves the reliability of the device for protecting a direct current motor against overload. The invention The device for protection of an electric current of a direct current generator against overload. Contains a converter supplying a direct current electric motor, made in the form of serially connected control pulse forming unit, the first input of which is connected to the input source, the thyristor rectifier, the output of the last connected to the DC electric motor, the threshold unit, the first input of which is connected to the source of the reference voltage, Vykhod - with VRE "m input of the unit and control pulses of the converter, the weight is due to the fact that, in order to increase the reliability of the device, the series-connected band-pass filter and detector are additionally introduced into the black, and the input of the band-pass filter is connected to the output of the thyristor converter / output converter the detector - to the third input of the progrogog block. Sources of information taken into account in the examination. 1. USSR author's certificate number 6815.31 cl. H 02 R 5/16, 1978. 2, USSR Copyright Certificate No. 519833, cl. H 02 R 5/06, 1975.