SU1115202A1 - Process for rectifier control - Google Patents

Abstract

THE METHOD OF CONTROLLING A RECTIFIER on a fully controlled ventilator, which means that for each fully controlled valve a conduction interval is determined, at the beginning of the conduction interval a first fully energized valve is generated and energized, a corresponding control phase is generated and a switching off pulse is applied to said fully controlled valve, the phase of the reclosing impulse is determined, a reclosing impulse is generated and fed to the indicated A new controlled valve with a previously defined phase, characterized in that, in order to improve the quality of the rectifier's operation, by reducing the ripple of the output parameter of the rectifier (current, voltage, power), the output parameter is measured separately for the first and repeated switching on of the fully controlled valve, filter and compare the measured parameter values, in case the measured parameter value (L corresponding to the first switch-on is greater than the value corresponding to the second one, then the previously determined phase of the repeated switch on Cheney decrease and increase in the opposite case.

Description

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The invention relates to electrical engineering and can be used in AC-DC converters and AC regulators. A known method of controlling a rectifier on fully controllable valves consists in that the valves are supplied with unlocking control pulses with an adjustable delay in relation to a voltage junction through zero, and a switching pulse is emitted when the current passes through zero SP. The disadvantage of this method is a large consumption of reactive power and a high level of harmonics. The closest to the proposed technical essence and the achieved results is the method of controlling the rectifier on fully controlled valves, which consists in determining the conductivity interval for each fully controlled valve, at the beginning of the conductivity interval form a fully controlled valve, in accordance with a predetermined control phase, a pulse of the specified fully controlled valve is generated and energized, an impulse phase is determined switching on the specified fully controlled valve with a previously defined phase C2 T. A disadvantage of the known method is the increased output signal ripple due to the fact that even with a symmetrical arrangement of the first blocking and second trigger pulses, the voltage pulsations of the current will not be equal to back EMF in the first stage. The purpose of the invention is to increase the quality of the rectifier by reducing the ripple level of the rectifier output parameter. The goal is achieved by the fact that, according to the method of controlling the rectifier, the conductivity interval is determined on a fully controlled valve, for each fully controlled valve a conduction interval is determined, at the beginning of the conduction interval, a first fully activated controlled pulse is applied. In accordance with a predetermined control phase, the valve forms and switches off the pulse indicated by the 11 fully controlled control valve, the phase of the reclosing pulse is determined, the pulse is formed and fed By re-enabling the specified fully controlled valve with a previously defined phase, the output parameter is measured separately for the first and re-activation of the fully controlled valve, and the measured values of the parameter are compared, if the value of the measured parameter corresponding to the first start is greater than corresponding to the second, the previously determined phase of the re-inclusion is reduced, and increase in the opposite case. FIG. 1 shows a diagram of an apparatus for carrying out the proposed method; in fig. 2 is a diagram of the operation of the device. The load 1 through the valve 2 is powered by a transformer 3. There is a sensor 4 output value, in this case a current sensor. Two amplifiers of 5 and 6 pulses are connected to the control input of the valve 2. In this case, amplifier 5 forms unlocking and amplifier 6 - locking pulses. An element OR 7 is connected to the input of amplifier 5. An initial trigger pulse driver 8 is connected to IZ 7, the input of which is connected to a network transformer 3. The inputs of phase control unit 9 are connected to transformer 3 and control unit 10. The second phase control unit 11 is connected to the output of the first element OR 7. The inputs of the unit 11 are connected to the outputs of two filters 12 and 13, the inputs of which are connected via switches 14 and 15 respectively to the output of the output value sensor 4. The control inputs of the keys 14 and 15 are connected to the outputs of the flip-flops 16 and 17. The reset input of the flip-flop 17 is connected to a driver 18 connected by an input to the output of the output-value sensor 4. The method is implemented in the following order of operation of the device. Load 1 is fed by a rectifier formed by valve 2. The number of rectifier valves may be different. According to the principle of operation, one valve is considered. Similarly, the device can also be built while regulating the alternating current, for which another valve is turned counter-parallel to valve 2.

Load 1 straightener can be inductive and contain a source of pro-. in-EMF (motor), in this case, the load 1 is shunted by a diode 19. When working on an active-capacitive load, such a diode is not needed. FIG. 2 of the notation: U - network voltage; Sv - rectifier current; 0ts - current nag-. ruzki.

Valve 2 is turned on at least two times in the conductivity interval. At the beginning, at time t ,, the driver 8 generates a pulse Ug, which triggers valve 2. The current of the first stage begins to flow. At the same time, J5 sends a trigger pulse to the S input of the trigger 16, the trigger turns on the key 14, applying a signal from the output of the sensor 4 to the input of the filter 12. The filter can be of various types. At time tj, determined by the phase shift unit 8, depending on the constant controlled signal of the control unit 10 with angle bd, a locking Impulse is applied to the valve 2 amplified by the amplifier 6. At the same time, the current from the network is cut off. Turning off the valve 2 is quite slow by gradually closing it with a special signal. In this case, Q must use an electronic valve or transistor. It is also possible to instantly lock this valve if a thyristor is used as it. At the same time, a capacitor 20 is turned on at the terminals of the transformer for damping overvoltages. When the thyristor 2 is turned on, the trigger is reset and the key

14 is locked, stopping in the future the signal to the filter 12 from the output of the sensor 4.

After pausing, at the moment ta, a second unlocking pulse is applied from the output of the second phase control unit 11. This pulse simultaneously with the opening of the thyristor 2 triggers the trigger 17, which connects the output of the sensor 4 to the input of the filter 13 using a second key 15. The current flowing through the valve 2 in the second section is filtered on the filter 13. In the second stage, the thyristor 2 turns on at time C when the current drops to zero. At the same time, the driver 18, upon the fact that the current vanishes, resets the trigger 17, the switch 15 is turned off, and the filter 13 is disconnected from the current sensor.

The signals from the outputs of the filters 12 and 1 are compared with each other at the input of the phase shift unit 11. The difference of these signals affects the phase of the control pulse in the second stage in such a way as to reduce to zero the difference between the signals of sensor 4.

The use of the proposed device allows to significantly reduce output ripple (in this case, current) at the output of the converter, which leads to a reduction in energy loss and a decrease in electromagnetic interference. The nature of the load does not affect the nature of the pulsations.

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Claims (1)

RECTIFIER CONTROL METHOD on fully controllable valves, consisting in the fact that for each fully controllable valve the conduction interval is determined, at the beginning of the conduction interval an impulse of the first inclusion of the indicated fully controllable valve is generated and applied, in accordance with a predetermined control phase, the impulse for said fully controlled valve, determine the phase of the re-enable pulse, form and feed the re-enable pulse to the specified fully control valve with a previously defined phase, characterized in that, in order to improve the quality of the rectifier by reducing the ripple of the output parameter of the rectifier (current, voltage, power), the output parameter is measured separately for the first and second switching on of the fully controlled valve, the measured values are filtered and compared parameter, if the value of the measured parameter corresponding to the first inclusion is greater than the value corresponding to the second, then I reduce the previously determined phase of repeated inclusion And increase in the opposite case.