SU1347140A1 - Device for controlling d.c. electric motor - Google Patents

Abstract

The invention relates to electrical engineering and m. Used in DC electric drives with a pulse-width converter. The purpose of the invention is to increase reliability. The device contains two pulse-width pulsed modulators (PWM) 1, 2 for reversing and controlling the electric motor 12, which is included in the diagonal of the transistor bridge assembled on the key elements 4-7. The introduction of two delay elements 14, 16 and logic elements AND 13, 15 allowed, while simultaneously switching elements in one shoulder of the transistor bridge, to avoid the occurrence of through short-circuit currents, which contributes to an increase in the quality indicators of the regulation. 1 il. (L 4

Description

The invention relates to electrical engineering, in particular to reversible direct current drives with pulse-width converters.

The purpose of the invention is reliability.

The drawing shows a functional diagram of the device.

The control unit of the DC motor contains two pulse-width modulators 1 and 2 and trigger 3, the S input of which is connected to the output of the first pulse-width modulator 1, and the R input with the output of the second pulse width modulator 2. In addition, the device contains a transistor bridge made up of key elements 4-7, each of which is bridged by a reverse diode 8-11, respectively. nen with output of the first pulse width modulator 1. The second input of the first AND gate 13 via the first delay element 14 is connected to a direct output of the flip-flop 3 and a control input of the first element 4 transistor bridge. The output of the first logic element And 13 is connected to the control input of the third element 6 of the transistor bridge. The first input of the second logic element AND 15 is connected to the output of the second pulse-width modulator 2. The second input of the second logic element AND 1 5 is connected via the second delay element 16 to the inverted input of the trigger 3 and to the control input of the second transistor bridge element 5 Second output logic element I I5 is connected to the control input of the fourth element 7 of the transistor bridge.

The device works as follows.

If it is necessary to rotate the electric motor 2. In front of the control pulses of the output from the pulse-width modulator 1 to the S-input of the trigger 3, the same signal is set at its direct output, which is equal to the delay of the delay element 16 on the control input of the first key

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element 4, opening it, and to the second input of the first logical element I 13, permitting the passage of control pulses from the tweeter-pulse modulator 1 to the control input of the third element 6, opening it with a duty cycle equal to the pulse ratio of the pulses -pulse modulator 1. Elements 5 and 7 of the transistor bridge are closed.

When the direction of rotation is reversed, the pulses appear at the output of the pulse-width modulator 2 and set at the direct output of the trigger 3 a zero signal, which already without a time delay goes to the control input of the first element 4, is closed. it, and the second input of the first element I 13, prohibits the passage of pulses, i.e. disconnecting item 6 of the transistor switch. With a time equal to the setpoint of the second delay element 16, a single signal from the inverted output of trigger 3 is fed to the control input of element 5, opening it, and to the second input of the second element 15, allowing passage of pulses to the control input of element 7, opening it with a duty ratio of pulses of a pulse-width modulator 2. At the next reversal of rotation, the device operates in the same way.

Thus, when the motor 12 is reversed, the device provides a time delay when switching transistor key elements connected in series on one side of the bridge, necessary to restore the locking properties of the transistor key elements in order to avoid through-currents.

Claims (1)

Invention Formula A DC motor control unit containing two pulse-width modulators, a trigger whose S input is connected to the output of a first pulse-width modulator, and an R input is connected to the output of a second pulse-width modulator, transistor bridge, each element of which is shunted, respectively, by a reverse diode, the diagonal of the transistor bridge is designed to be connected to the electrical motor's core winding, distinguished 3, 13471404 Right now, in order to noBbme its transistor bridge element, neither reliability, it is equipped with two first input-second logical delay elements and two logical AND connected to the output of the second And, the first input of the first-pulse-width modulator, of the logic element And the connected input of the second logic element by the output of the first pulse-width pulse And through the second delay element modulator, the second input of the first log is connected to the inverse output of the triggered element And through the first ele-ra and the control input of the second ele The delay is connected to the direct Q of the transistor bridge, the output of the trigger output and the control input logic element AND the sub-first element of the transistor bridge, is connected to the control input of the fourth and the output is to the control input of the third-element transistor bridge.