SU1750003A1 - Control gear for reversible three-phase converter with double connection of rectifiers - Google Patents

Abstract

SUMMARY OF THE INVENTION: The device contains for each set of power valves of a converter a symmetric phase shifter (FSC) with control pulses of 120 el. and a logic device for generating control signals for reclosing the valves connected to the clock and control signals of the FSC. In this case, each channel of the logical device is made in the form of sequentially connected logical elements 2И-BANNED 2, OR. Zil.

Description

The invention relates to a converter technique and can be used, for example, in reversible direct current drives with a reverse current of the core.

A device for controlling a bridge reversing converter is known, containing for each set of power valves a symmetric phase-shifting device (FSU) with wide control pulses (more than 60 el.grad.) And a logic device for generating additional control signals providing a double-switching mode of the valves, Also common to both power sets is an output voltage transducer sensor. The logic devices of both power sets are connected to the output signals of the corresponding FSU, the output voltage sensor of the converter, and also the link of the automatic control system of the converter that determines the mode of operation of the converter: rectifier or inverter.

The disadvantages of the known device are:

- lower speed in the process of reversing the converter, carried out with energy recovery to the AC mains supply network, due to the fact that the entire recovery stage is performed in the single-switching mode of the converter valves;

- lower reliability due to the complexity of its structure, due to the presence of an output voltage sensor of the converter and connections to the power section of the converter and its automatic control system.

The aim of the invention is to increase the speed of the converter in the process of its reversal and increase the reliability of the device by simplifying it.

The goal is achieved by the fact that in a device for controlling a reversible three-phase converter with double switching of valves, containing for each set of power valves, fac (/)

WITH

vj СЛ О О О

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a moving unit equipped with three inputs for connecting synchronizing voltages, forming a system of symmetrical pulses at its six outputs, six OR elements whose outputs are device outputs, and the first inputs are connected to the corresponding outputs of the phase-shifting unit, and a pulse shaping unit to re-enable the valves , a phase-shifting unit was used, forming output pulses with a width of 120 electr., three comparators were inserted into the pulse-shaping unit to re-enable the valves; One-vibrators and six And elements equipped with prohibition inputs, while the outputs of the And elements are connected to the second inputs of the corresponding elements OR, the first inputs of the And elements are connected to the outputs of the corresponding one-vibrators, the inputs of the one-vibrators are sequentially combined into pairs connected to the outputs of the corresponding comparators whose inputs with the corresponding inputs of the phase-shifting unit, wherein the elements AND the second inputs are connected respectively with the third, fourth, fifth, sixth, first and second outputs fazosdvigeyuschego unit and prohibition inputs connected respectively to the sixth, fifth, second, first, fourth and third outputs of the phase shifter unit

Fig. 1 shows a functional diagram of a control unit for one set of reversible converter power valves and a diagram of the set of power valves itself; FIG. 2 shows timing diagrams: axis I — phase voltages of the supply network UA, UB, Uc; axis II — synchronizing voltages of the FSA DAB. UBC, UCA, and single-vibrator output voltage pulses, along the A-Z axes, are shown the control signals of the FSO through the corresponding channels of the three-phase converter bridge circuit for three values of the control angles: 30, 90, and 150 hl; Fig. 3 -circuit realization of the elements 2I-ZALRET on the basis of the serial chip K 155L44.

The device contains a symmetric FSU 1 (the AZ symbols denote control channels for the power valves of the cathode and anode converter groups), comparators 2-4, single-oscillators 5-10, elements 2I-BAN 11-16, elements 2ILI 17-22, power valves 23 of the converter, load 24 converter

Comparators 2-4 are connected to the appropriate FSU clock voltages and convert the voltage.

sinusoidal to rectangular voltage. In this case, the single vibrators 5, 7, 9 operate with positive polarity signals at their inputs, and the single vibrators 6, 8, 10 operate with the presence of negative polarity signals of the synchronizing voltage.

The second inputs AND and the inhibit inputs of the elements 2I-BAN, as well as the second inputs of the elements 2 OR are connected to the corresponding control channels of the FSU.

The control unit provides the following order of operation of the converter,

In rectification mode.

In the range of control angles a 0-60 e hail, only control pulses are fed to the converter valves with the FSU. The converter operates in this case.

single-valve mode In the range of adjustment angles "60-120 el.grad. control pulses are supplied to the converter valves from the phase-shifting and logic devices

The converter operates in double valve switching mode.

In the mode of inversion of the converter. In the range of angles of regulation 180-120 el.grad. Only control pulses are fed to the converter valves. 1 The converter operates in the single-valve switching mode. In this case, energy is recovered to the supply network.

In the range of adjustable angles of 120-60 e-hail, control pulses from the phase-shifting and logic devices are applied to the converter valves.

The converter operates in the double-switching mode of the valves; there is no energy recovery to the power supply network.

The operation of the control device is considered on the example of a reversible electric direct current drive with a current reversal of the core.

The inclusion of the FNU 1 is made by a signal from the control system (not shown in Fig. 1). In this case, the FSU produces

a symmetrical system of control pulses that are applied to the second inputs of logic elements ORD, and from their outputs to the control electrodes of the converter valves.

In rectification mode in the range of angles of adjustment a 0-60 zl.grad. (for example, at a 30 electr. grades) by the impulse of the FSU at the moment of time and it turns on through the logic element 2ILI 17 gate A.

load starts to flow through the valves AU. At the time point g, an FSU pulse through gate 2ILI 22 turns on valve Z. A load current begins to flow through valves AZ. Further valve switching proceeds similarly. The converter operates in a single valve turn-on mode. The valve switching cycle has the following

VIEW

AY-AZ

AZ-BX

CX-CY

In the rectifying mode, in the range of adjustment angles of 60–120 electragrad (for example, at “90 el.grad) at time t2, the impulse of the FSO turns on valve A. The load current begins to flow through the valves AY. From time t3, the clock voltage UAB takes a negative value. In this case, the single-vibrator 6, according to the signal from comparator 2, produces a short-term pulse (see FIG. 2). Thus, on logic element 21/1-BAN 12 there are signals at both inputs AND, and there is no signal at the inhibit input. At this, element 2 И BAN 12 turns on and through element 2 OR 18 outputs a control signal to gate X.

Valve X is turned on and the load current begins to flow through the valves AX. At the end of the output pulse of the one-vibrator 6, the logic element 2I-BANGE 12 is turned off, the control signal from the valve X is removed, but the load current continues to flow through the valves AX.

At the moment of time m.4, the impulse of the FSO turns on the valve Z, the load current begins to flow through the valves AZ. Further valve switching proceeds similarly.

The converter operates in double valve switching mode. The cycle of switching valves is as follows:

AY - AH - AZ - CZ

BZ-BY-BX-AX

CX - CZ - CY - BY

When the converter is operating in a rectifying mode in the range of adjustment angles a - 0-120 el.grad. the engine is running in motor mode

When reversing the engine in the first stage (braking from a predetermined rotational speed to zero), the engine operates in generating mode. At the same time, in the range of adjustment angles is 180-120 el.grad. the converter operates in the inverter mode;

unipolar converter voltage.

The operation of the control device in this mode is considered at an angle of control of 150 al. At time t4, the A signal of the FSO turns on valve A, the load current begins to flow through the AU valves. At the time ts, the signal of the FSO turns on the valve Z, the load current begins to flow through the valves AZ. Thus, the converter operates in a single valve turn-on mode.

With further braking in the range of angles of regulation a 120-60

5 e hail, the converter is switched to the double valve switching mode. In this case, the recovery of energy to the network is stopped, and only those segments of the converter voltage that are added to its voltage are applied to the motor core (as opposed to the single switching mode of the valves, when alternating voltage of the converter is applied to the motor core). Job

5 of the control device is similar to operating in a rectifying mode in the range of adjustment angles of 60-120 al. Degrees. Thus, in the proposed device due to the use of the double-switching mode of the valves in the range of adjustment angles a 120-60 el.grad. in the process of inverting the converter, the voltage ripple on the load is reduced, the zone of intermittent currents is narrowed. Ultimately, this leads to an increase in the speed of the converter. The increase in the speed of the converter for the case of direct current drive with a current reverse of the core ensures that its speed and accuracy are improved. braking and reverse modes.

By eliminating the voltage sensor of the converter and the electrical connections to the power section of the converter and the automatic adjustment system, the device has a simplified structure that provides increased reliability. Formula of Invention A device for controlling a reversible three-phase converter with double switching of valves, containing for each set of power valves a phase-shifting unit equipped with three inputs for connecting synchronizing voltages, forming at its six outputs a system of symmetrical pulses, six elements OR whose outputs are exits

devices, and the first inputs are connected to the corresponding outputs of the phase-shifting unit, and a pulse shaping unit for re-energizing the valves, so that, in order to increase the speed of the converter during its reversal and increase the reliability of the device by simplifying it, a phase-shifting unit forming output pulses of 120 electr. width width. Three comparators were inserted into the pulse shaping unit to re-energize the valves; ban's inputs while the outputs of AND gates are connected to the second inputs of the corresponding

0

five

the OR elements, the first inputs of the AND elements are connected to the outputs of the respective single vibrators, the inputs of the single vibrators are sequentially connected in pairs, connected to the outputs of the corresponding comparators, whose inputs are connected to the corresponding inputs of the phase shifter b, and the elements And the second inputs are connected respectively to the third, the fourth, fifth, sixth, first and second outputs of the phase-shifting unit, and the prohibition inputs are connected to the sixth, fifth, second, first, fourth, and third outputs of the phase shift, respectively of the blocking unit.

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Claims (1)

. Claim A device for controlling a reversible three-phase converter with double switching on the valves, containing a phase-shifting unit for each set of Power valves, equipped with three inputs for connecting synchronizing voltages, forming a system of symmetrical pulses at its six outputs, six OR elements, the outputs of which are the device outputs, and the first the inputs are connected to the corresponding outputs of the phase-shifting unit, and a pulse forming unit for re-turning on the valves, which differs by oh, in order to improve the speed of the converter during its reversal and to increase the reliability of the device by simplifying it, a phase-shifting unit is used that generates output pulses with a width of 120 electric degrees, three comparators, six single-vibrators and six elements are introduced into the pulse-forming unit for re-switching the valves And, equipped with prohibition inputs, while the outputs of the AND elements are connected to the second inputs of the corresponding OR elements, the first inputs of the AND elements are connected to the outputs of the corresponding single Orov, the inputs of one-shots are connected in series in 5 pairs connected to the outputs of the respective comparators, the inputs of which are connected to the corresponding inputs of the phase-shifting unit, while the elements And by the second inputs are connected respectively with the third, fourth, fifth, sixth, first and second outputs of the phase-shifting unit and the prohibition inputs are connected respectively to the sixth, fifth, second, first, fourth 15 and third outputs of the phase-shifting unit. Fig.Z