SU843138A1 - Device for emergency dunamic braking of dc electric motor with winding of parallel excitation - Google Patents

Description

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The invention relates to electrical engineering and can be used in thyristor electric drives of direct current with a converter, made by a bridge circuit.

The closest to the proposed device for emergency dynamic braking of a parallel-excitation direct current motor includes a valve converter connected to the electric motor core circuit, a valve converter control unit and a command for dynamic braking, the driver input is connected to the switch output, the contacts of which bypass the resistor dynamic braking and which is included in the core of the electric motor, and one of the outputs of the driver under Key to control valve converter fi

The disadvantages of this technical solution are the low efficiency due to the presence of droplets, 7difficative dynamic braking current, the need to disconnect the supply voltage in order to achieve dynamic braking. With group meals from one

transformer it is impossible to carry out dynamic braking of one of the actuators.

The purpose of the invention is to increase efficiency and expand the functionality of the drive.

The goal is achieved by the addition of a serially connected unit to the device.

0 delay, the driver of the command to remove the control pulses and the matching unit, the input of the matching unit connected to the second output of the driver of the dynamic deceleration command, one output of the matching unit to the motor driver, and the other of its output to the driver control pulses, the output of which is connected to the first input of the blocks, control, the second input of the control unit is connected to the output of the delay block.

SUMMARY OF THE INVENTION The drawing, which shows the scheme of the device for emergency dynamic braking of an electric machine.

The device contains a valve converter 1, made on the basis of a bridge circuit, a converter control unit 2, a direct current electric motor 3, a circuit breaker 4 installed in the rectified current circuit, in parallel with which a dynamic braking resistor 5 is connected, a dynamic braking driver b, connected to the unit 7 matching the polarity of the EMF of the electric machine with the direction of conduction of the valve, the converter, the output of which is connected to the input of a forshrovater 8 coma rows on deprotection steering pulses, the output driver 8 is connected to the input of the delay block 9, through which the output matching circuit connected to the gate electrodes of all the valves of one phase anchoring transducer.

. The device for emergency dynamic braking is operated as follows.

In the event of a fault in the converter or by other necessity, the dynamic braking command driver 6 generates a brake command signal, at the same time the automatic switch 4 starts to turn off, the current of the converter 1 is redistributed inversely proportional to the resistance value of the dynamic braking switch 5. When the signal for braking is applied, the control impulses are pushed into the inverter region, and depending on the emergency process, the converter 1 is limited to its current. The same signal is fed to the input of the block 7 for matching the polarity of the EMF of the electric machine with the conduction direction of the converter. Unit 7 gives the command to change the direction of the excitation current of the electric motor 3, and when working with a weak field, also to increase it to the nominal one if the converter 1 is non-reversible and operated in the rectifier mode. If the converter 1 is reversible or worked before braking in the inverter mode, then the command to reverse the field current is not received. Only when working with. the weakened field receives a command to level the current up to the nominal current. The signal from block 7 is sent to the shaper 8, commands to remove the control pulses. Shaper 8 is removed on signal

 control pulses and turns on

block 9 delay. The delay unit 9 produces control pulses with a delay of time relative to the input signal, which through the matching and galvanic isolating circuits are supplied to the control electrodes of all the gates of one phase of the converter 1. The time delay of the unit 9 is selected so that the current in the core circuit starts from continuous dropped to zero after removing control pulses. The pulses of the delay unit 9 unlock the valves of one phase of the converter 1 and close the power circuit for dynamic braking of the electric machine.

Claims (1)

1. US Patent No. 3786329, cl. H 02 .P 3/12, 1971. Into 5 & 8 & 5 & &