SU1385215A1 - D.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used to control the speed of an electric motor. The aim of the invention is to increase efficiency. The device contains a module 6 module allocation, the output of which is connected via relay elements 7, 8 to the inputs of logic block 4. The input of module 6 of the module is connected to the output of current sensor 5. The device ensures the formation of a unipolar voltage sequence on the load. As a result, the required switching frequency to provide the same amplitude of current ripple is more than halved. 1 il.

Description

This invention relates to electrical engineering and can be used in direct current drives.

The purpose of the invention is to increase efficiency,

In the drawing, the device circuit got stuck

The device is current-limiting for a DC electric drive, the device operates as follows.

At the driver inputs of the relay elements, the maximum current setting I, |

The signal b at the output of the first relay element 7 is formed when the instantaneous current value is reached

keeps the motor, 1, connected - Q values-I and keeps its

connected to the pulse bridge transistor converter 2, modulator 3, logic block 4, the first and second inputs of which are connected respectively to the first and second drives of the modulator 3 and serially connected motor current sensor 5, block 6 of the module and the first relay element 7, output which is connected to the third input of block A

a value equal to one until the load current drops to the rank (hister loop width is 2d1), the output signal 5 of the second relay element forms when the current reaches Irp + Ciin and retains its value equal to one to those until it drops to a value (shi on hysteresis loops is 2bi, j),

20

and s ft 1

with transistor bases, in the current-limiting mode at ground level, 2. the instantaneous value of the current

In addition, the electric drive contains .loads of magnitude at the time of the second relay element 8, the output of which by the time it triggers the first relay

first connected to the fourth input of logic unit 4, the first input of the relay element 8 is connected to the output of the module allocation module 6, the second inputs of the relay elements 7 and 8 are connected to the maximum current setting unit, and the logic unit 4 implements the following logical functions

V, a b b +

V. DLB

Ultrasound

V ;,; (bv b-),

where | , V-, V «, V, - output signals

block 4 logic; 1, 1 (2 output signals

modulator 3;

b, b are the signals at the outputs of the first and second relay, respectively, of elements 7 and B.

The transistor converter 2 is made in a bridge circuit on transistors 9,10,11 and .12 with reverse diodes 13,14,15 and 16. In one diagonal of the bridge, the DC motor connected in series with the current sensor 5 is connected, and the other diagonal is a constant voltage source. The transistors are controlled by the output pulses of the 4 V -V, block, and this corresponds to the on state of the transistor, and to the off state.

a value equal to one until the load current drops to a value (the width of the hysteresis loop is 2d1), the signal at the output of the second relay element is formed when the current reaches Irp + Ciin and retains its value equal to one until until the current drops to a value (the width of the hysteresis loop is 2bi, j),

and s ft 1

 In current mode, instant

five

element 7, locking, first of all, the keys (transistors) 9 and 10, opening the keys 11 and 12. Moreover, if the current is limited

0 In the motor mode, the current of the core is closed in the circuit opposite to counter-electromotive force, which causes its decrease. When the core current decreases by 2 / vi, the action of the current-limiting device on the state of the keys is terminated. The signal b thus becomes zero. Further, depending on the control signal, the current can either increase or decrease again. In the first case, the current limitation will come into effect when the load current reaches the value I |. + &Amp; i and everything will repeat, and in the second case, the operation of the current limit on this stops. If, however, the current limiting is performed in the deceleration mode, then after locking the keys 9 and 10 and opening the keys 11 and 12, the current of the core is closed in the circuit, according to the resistance of the electromotive force. cor. And depending on the ratio of the counter-emf of the core and the setting of the current-limiting 1 current, the core will either decrease, or continue to increase, but at a slower rate. The first case is similar to the operation of the current limiting in the motor mode, in the second case the key management algorithm is as follows. Moment of achievement of instantaneous current

five

0

five

values (j, the second relay element 8 is triggered, not only the keys 9 and 10 are locked, but also the keys 11 and 12. The main current closes in the circuit opposite the power source, which reduces it to IrrTui, switching and switching on the keys 11, 12, after which the current core again will increase.

The device current limit provides in all modes of operation the formation of a unipolar sequence of voltage across the load (ensures asymmetric switching of keys). As a result, the required switching frequency to provide the same amplitude of current ripple, ensuring a symmetrical law, is reduced by more than two times. This, in turn, leads to a decrease in switching losses, which, when the pulse converter operates in high-speed electric drive systems, loss share.

Claims (1)

Invention Formula A DC motor, containing an electric motor connected to a pulse bridge transistor converter, modulator, logic unit, first and second five 0 five the inputs of which are connected respectively to the first and second outputs of the modulator, and the motor current sensor connected in series, the module allocation module and the first relay element, the output of which is connected to the third input of the logic block, four outputs of which are connected to the bases of transistors of the converter, differing from the fact that, with the aim of increasing the efficiency, the second relay element is introduced into it, the output of which is connected to the fourth input of the logic block, the input of the second relay element is connected to you the movement of the module allocation unit, the second inputs of the relay elements are connected to the block for setting the maximum current, and the logic block implements the following logic functions V V, b b 1 V3 V4 v; b b - V, (b b V, (bV b). 0 where V i output signals block of logic; y, y are the signals at the modulator output; signals at the outputs of the first and second relay elements, respectively B b +