SU1527685A1 - Device for protection of electric drive with adjustable converter and velocity transducer - Google Patents

Abstract

The invention relates to the field of electrical engineering, in particular to the relay protection of an adjustable electric drive. The purpose of the invention is to simplify and improve the reliability of the device. When the circuit of the speed sensor 3 is broken in series with the capacitor of the RC generator 4, only one total load resistance R _e of the speed sensor 3 is turned on. As a result of the insertion loss, a generator 4 is disrupted, and a blocking signal appears at the output of the block 5, which turns off the adjustable thyristor converter. LED 6 serves as an indicator of device response. 2 Il.

Description

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The invention relates to electrical engineering, in particular, to an adjustable electric drive, and may find application in electric drives of machine tools and other mechanisms,

The purpose of the invention is to simplify the device and increase its reliability.

FIG. 1 shows a diagram of a device for protecting an electric drive; Fig. 2 shows timing diagrams explaining the operation of the device.

The device contains an adjustable transducer 1, equipped with inputs for connecting to motor 2 with speed sensor 3, square pulse generator A, blocking node 5 and LED 6,

The output of the speed sensor 3 is connected to the inputs of the generator A of rectangular pulses and the adjustable converter, and the output of the block 5 of the blocking is connected to the blocking input of the adjustable converter and through the LED 6 to another input of the generator 4 of rectangular pulses.

The device works as follows.

The square pulse generator 4 can be performed, for example, on an operational amplifier 7 and is an asymmetrical multivibrator with a single phase-shifting RC target.

Since generator 4 is a source of continuous oscillations, a voltage is present at its output, the amplitude of which periodically varies between the limiting levels determined by the tip of the output stage of the operational amplifier 7,

The negative polarity pulses through the first diode 8, the filter consisting of the resistor 9, the capacitor 10 of the blocking node 5, arrive at the base of the latching transistor 1 1 of the blocking node 5 and keep it in the locked state. The negative bias level at the base of the latching transistor 11 is limited by the second diode 12 (point B). Capacitor 10 helps to maintain a negative bias for the duration of the positive output pulses of the generator 4. There is no blocking signal at the output of the block 5.

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If the speed sensor circuit 3 is broken in series with the capacitor 13 of the generator 4, only one total resistance of the load 14 of the speed sensor 3 is turned on.

As a result of the attenuation, the generator generates 4th generation, the voltage at its output (point A) becomes zero, and from this moment the capacitor 10 begins to recharge on the circuit: plus power supply, second resistor 15, third blocking resistor 16. The voltage at the base of the latching transistor 11 rises, and as soon as it exceeds the unlocking threshold, the transistor 11 will open at the output of the node

5 blocking according to the blocking signal.

The positive voltage from the output of the blocking unit 5 is fed through the light-diode 6 to the other input of the generator

4 coral pulses, for example on a non-inverting input of the operational amplifier 7, and fixes the device

in the state of srabatshan. Light-emitting diode

6 serves to indicate the device’s first time response,

To ensure the required device speed

The 5 blocking is chosen so that the time tg of recharging capacitor 10 to the response voltage Ucp from the moment the speed sensor circuit 3 is broken does not exceed the duration of one period T of the generator 4 impulses. be regulated

over a wide range.

When the speed sensor circuit 3 is bad at the time of the negative output pulse of the generator 4, the block 5 activation time decreases because during the previous positive pulse a partial capacitor 10 discharges along the circuit: the third resistor 16, the second blocking diode 5, and therefore , the recharge time of the capacitor 10 to the voltage of the unlocking of the clamping transistor 1 is reduced (FIG. 2)

Breaking the input circuit of generator 4 is equivalent to connecting in series with the capacitor 13 an additional resistance, which, based on the foregoing, leads to a breakdown of the generation and the appearance at the output of node 5 of blocking the blocking signal.

When the output circuit of the generator 4 is faulty, the supply of negative bias to the base of the latching transistor 11 is stopped, the latching transistor 1I opens and a blocking signal appears at the output of the blocking unit 5.

The voltage jump appearing at the input of the generator 4 when changing the sign of the output voltage of the speed sensor 3, for example, when reversing the electric motor 2, does not affect the operation of the device, since, for example, a positive polarity output generator

4 does not arrive at the input of the blocking unit 5 and the capacitor 10 does not have time to recharge during its operation before unlocking the voltage of the clamping transistor 11, and the negative polarity pulse only maintains the clamping transistor 11 in the closed state.

Thus, the device can be used in electric drives based on both non-reversible and reverse thyristor converters.

Interference immunity of the device is ensured by the fact that in the working mode the locking transistor of the P node

5 blocking locked negative

the offset supplied to its base from the output of the generator 4,

An additional advantage of the device is that the elements of the device circuit do not require selection in the manufacturing process.

Thus, the use of a generator of rectangular pulses in the device of protection of the electric drive has significantly simplified its circuit design, expanded the scope of application and increased reliability.

Claims (1)

5 claims 1, A device for protecting an electric drive with an adjustable transducer and a speed sensor against an open circuit of the speed sensor, comprising an RC pulse generator with an input for connecting to the control input of the converter and a blocking unit, in order to simplify and improve the reliability of the device , the output of the RC generator of rectangular pulses is connected to the input of the blocking node, the output of which connected to another input of the RC generator of rectangular pulses and intended to be connected to the blocking input of the converter, 2, the device according to claim 1 and about 5, and 5 such that the output of the blocking node is connected to another input of the square pulse generator via an input LED. 0 five