SU577631A1 - Device for reversing control of dc electric motor - Google Patents

Description

one

The invention relates to a conversion technique and can be used in devices for controlling DC motors used in positioning systems, in particular in machine tools with software; management.

Devices are known for controlling DC motors operating at two speeds, in which the direction of rotation is periodically changed at arbitrary intervals of time. Gear shifting and reversing is carried out by means of gears to mechanical switches 1, 2.

However, these devices are cumbersome, complex and unreliable in operation due to the presence of a dead one.

The closest in technical essence to the proposed device is an electronic control system of a direct current motor, comprising a synchronized power supply unit, a reference voltage unit, a full-wave shooting gallery, a rectifier with a pulse shaper, and a phase regulator H.

The disadvantage of such devices is the difference in the starting.moment at higher and lower speeds.

The purpose of the invention is to obtain the same starting torque at higher and lower speeds.

In the proposed device for reversing control of a direct current motor comprising a power supply unit, a reference voltage unit, a full-wave thyristor rectifier and a pulse shaper, this is achieved due to the fact that it is additionally equipped with a logic unit and a low-speed driver, which is connected via a logic unit with a pulse shaper, with the reference voltage unit being connected to the low speed shaper by one of the outputs.

The drawing shows a block diagram of a device for reversing motor control.

The device contains an engine 1, a two-half-time controlled rectifier 2 on thyristors, an engine power supply unit 3, a reference voltage unit 4, a shaper of 5 thyristor control pulses, a logic unit

6, the driver 7 signals of low speed.

Engine control 1 is as follows.

The right or left rotation of the motor is set by a two-wavelength rectifier 2 on thyristors. The expander 2 consists of four thyristors. Moreover, the right and left rotation of the motor is determined by the operation of one or another pair of thyristors, i.e. in fact, rectifier 2 consists of two independent rectifiers. Each of the thyristor pairs is controlled by b signals received by the generator of 5 thyristor-control pulses. The power supply of the rectifier 2 is realized from the engine power supply unit 3 by a variable sinusoid voltage, synchronized with the mains voltage. The two inputs of the driver 5 of the control pulses from the block 4 of the reference voltage are supplied, the first memory voltage shifted relative to each other by 180 °, synchronized with the network voltage, the Forcing of the control signals with a trickle switch occurs through two channels. The first channel is intended to form and control the,. snyhronirovannyh. with put the bodies half-waves of supply voltage. The second channel is, respectively, with differing half-waves. The voltage pulses are formed in the driver 5 for the control pulses at the moments when the network voltage passes through zero and are close in shape to square. The mode FO1 "1Pulse pulses is set by a logical unit 6, at the output of which the signal allowing the formation can be either constant or can arrive at certain time intervals. The outputs of the logic unit 6 receives signals from the imaging unit 7 signals of low speed, and on lines 8.9 from an external device - the signals of the speed selection. The shaper 7 signals of low speed consists of two single vibrators. The first Binary Vibrator operates in the mode of dividing the frequency of the reference voltage synchronized with the network voltage. The second one-shot works synchronously with the first, but the duration of its pulses is determined by the choice of the low speed value. The repetition period of the signals of the first single vibrator determines the period of the following groups of pulses of the low speed signal generator 7. The pulse duration of the second one-shot determines the number of pulses in these groups. The speed selection signals are fed to the logic unit 6 from an external device via lines 8.9. When a higher speed is selected, a single level signal is sent on line 8, and on line 9, the left signal level. At the output of the logical block, the output signal level is constant and is permitting for operation of the control impulses 5, the output of which are thyristor-controlled square-wave pulses. As a result, the full-wave rectified voltage is constantly applied to the motor and the motor operates at higher speed. When a lower speed is selected, a zero level signal is given via line 8 on line 9 - unit. In this case, the signal at the output of the logical interconnection will take the form of square pulses, the length of which is determined by the signals from the imager 7. during the time that the resolver of the logic unit 6 arrives from the logic unit 6, At the output of the pulse shaper, rectangular pulses appear. With a forbidding signal level, no pulses are generated. Accordingly, the motor is energized by groups of half-periods of the rectified voltage, repeating at regular intervals. With this engine; maintaining the moment required for the system to move will rotate at a slower speed. The element zigicity, which reacts to overcurrent in the motor winding, protects the motor against current overload.

; The use of the proposed device for reversing motor control of direct current allows the design and manufacture of positioning systems with the necessary speed and accuracy, which is achieved by introducing two speeds into the positioning algorithm without special requirements to the accuracy of the mechanical part of the system. This makes it possible to use simple ones (for manufacturing parts that are highly economical .. i. These advantages simplify the technical realization of machine tools with programmed control, reduce their streamer and simplify operation. In addition, the proposed device has less interference than the prototype with the same power of the motor due to the fact that the supply voltage is applied to the motor winding always at the moment of going through zero in contrast to the prototype, where the half-wave voltage is cut off in phase.

OopMyjfa invention

A device for reversing control of a DC motor, containing a power supply unit, a reference voltage unit, a full-wave thyristor rectifier and a pulse shaper, is distinguished so that, in order to obtain the same starting torque at higher and lower speeds, it is additionally equipped a logic unit and a low-speed signal shaper, which is connected via a logic unit to an impulse shaper / with a reference voltage block;

One of the outputs is connected to a low speed driver.

Sources of information taken into account in the examination: l. Patent of Germany f 1900621, cl. 42 p 23/04,

2. The US patent (# 3594625, class 318-257,

1971

3. US patent number 337 1 258, cl. 318-294,

1968.