SU1598094A1 - Reversible d.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used for installations requiring speed and torque control with limited speed and high operational reliability. The purpose of the invention is to increase reliability by limiting the short-circuit current when braking an electric drive. The increase in the crust current is monitored by the sensor 21 and, after exceeding the setpoint signal determined by the braking current adjuster 24, the additionally introduced threshold unit 23 is opened. A signal acting on the second subtractive input of the torque adjuster 9 is received at the second subtractive input of the adder 8. The drive current and the emf of the electric motor 1 are reduced. Further deceleration of the electric drive occurs at a given permissible value of the main current. 1 il.

Description

The invention relates to electrical engineering and can be used for installations requiring speed and torque control with limited speed and high operational reliability.

The purpose of the invention is to increase reliability by limiting the short-circuit current when braking an electric drive.

The drawing shows a diagram of the drive.

The electric drive contains an independent excitation motor 1 with a tacho generator 2. The armature winding of the motor 1 is connected to the terminals of an alternating voltage source through a series-connected reversing rectifier; hmitel 3, a matching transformer 4 inductive-capacitive converter 5. The winding of the motor exciter b is connected to the output of block 7 control, the input of which is connected to the output of the adder 8. The summing input of the adder 8 is connected to the output of the setpoint 9 of the moment. The subtracting input of the adder 8 is connected to the output of the threshold unit 10, the first and second inputs of which are connected respectively to the output of the tachogenerator 2 and the input of the rotational direction sensor 11, the output of the speed setpoint 12 and the input of the I / O unit 13. The outputs of the sensor 11 and the unit 13 are connected to the corresponding inputs of the logical distributor 14, the outputs of which are connected to the reversing rectifier valves 3 through the corresponding amplifiers 15-20. In addition, the electric drive additionally contains a current sensor 21, a series-connected selection module 22 and the second threshold unit 23, as well as the brake current sensor 24. The output of the setpoint 24 is connected to the second input of the second threshold unit 23, the output of which is connected to the second subtractive input of the adder 8. The output of the current sensor 21 of the core is connected to the input of the module 22 allocation module.

Reversible electric drive works as follows.

Signals are output from setpoint adjusters 9, 12, and 24. The speed selector signal determines the response threshold of the first threshold unit 10, and the setting signal of the 24

braking current - the second threshold unit 23. At the same time, the speed reference signal is fed to the input of the I / O unit 13, which converts the analog output signal of the speed master 12 into single ones

M and N signals, with the help of which external control commands are coded: Forward, Stop and Back.

The directional direction sensor 11 generates signals K and R, the combination of which allows to control both the rotation of the engine and the direction of this rotation.

When entering, for example, an external control command Forward logical

the distributor 14 provides for the connection of the corresponding valves of the reversible rectifier 3, which in the main circuit of the electric motor 1 causes a positive current, not exceeding

largest nominal value. The timing knob 9 acts on the control unit 7, which generates in the excitation winding 7, for example, a nominal excitation current. The electric drive is accelerated at even speed to the speed specified by unit 12. When the tachogenerator 2 exceeds the setpoint 12 signal, the first threshold unit 10 opens and passes the analogue signal of the tachogenerator 2 to the input of the adder 8. This signal acts counter to the output signal of the setpoint 9 moment, which leads to a decrease of the excitation current in the winding 6 and, as a result, reduction of the electromagnetic torque of the engine. With

the equality of the moment developed by the electric motor to the moment of resistance is achieved by the steady state operation of the electric drive.

With the arrival of an external control command, the Stop logic distributor 14 provides the connection of the rectifier valves 3, creating a negative current in the core circuit. The drive brakes.

Claims (1)

mode of inhibition. The negative feedback signal for speed is reduced, which leads to an increase in the excitation current and the EMF of the electric motor 1. At some EDS. the core is disturbed by the switching of the rectifier valves 3 and the electric drive switches to the dynamic braking mode, accompanied by an increase in the current in the core circuit. This increase in current is monitored by sensor 21 and, after exceeding the setpoint signal determined by setter 24, a second threshold unit 23 is opened, as a result of which the second subtractive input of adder 8 receives a signal acting opposite to setpoint setpoint 9. The resulting signal at the output of adder 8 decreases, which leads to a decrease of the excitation current in the winding 6, and therefore the emf of the core. A further increase in the braking current is terminated and the subsequent braking of the electric drive occurs at a given allowable value of it. Claims of the Invention A DC reversible electric drive containing an independent excitation motor with a tachogenerator, the electric motor's main winding is connected to the terminals of an alternating voltage source through series-connected reversible rectifier. - matching transformer and inductive-capacitive converter; motor excitation winding is connected to the output of the control unit, the input of which is connected to the output of the adder, the summing input of which is connected to the output of the torque adjuster, and the subtracting output of the threshold unit, the first and second inputs of which are connected respectively to the output - 10th house of the tachogenerator and the input of the rotational direction sensor, the output of the speed limiter and the input of the I / O unit, the outputs of the rotational direction sensor and the I / O unit are connected with sootvetst15 vuyuschimi logic inputs of the distributor, the outputs of which are connected through respective amplifiers to-conditioners rectifiers reverse rectifier, characterized in that, in order 20 improving reliability by limiting the short-circuit current when the electric drive is braked, a current core sensor is added in series, a module allocation unit connected in series and a second threshold The 25th unit as well as the brake current adjuster, the output connected to the second input of the second threshold unit, the output of which is connected to the second subtractive input of the adder, the output of the current sensor core sub30 are connected to the input of the allocation module of the module.