SU481115A1 - Method of disconnecting a three-phase autonomous inverter with group switching - Google Patents

Description

one

This invention relates to the field of converter technology.

There is a known method of disconnecting a three-phase autonomous inverter with group commutation, which consists in the fact that the generator generates control pulses for controlling power and switching thyristors.

The proposed method allows to increase the reliability of the inverter. This is achieved by switching the thyristor control emulsion generator in the time interval from the end of the next pulse, followed by an arbitrary switching off moment of the power thyristor control emulsion generator, until the expected subsequent pulse to the switching thyristors.

Pa figs. 1 shows a diagram of a three-phase, tri-core autonomous inverter with coarse switching, for the shutdown of which the described method was used; in fig. 2, a-l - timing diagrams of currents and power supply for individual elements of the inverter.

C;: new thyristors 1-6 are unlocked by pulses supplied from the generator of power thyristor control pulses (SMIs) that are part of the control system (SU). The commutator and its thyristors 7 and 8 are controlled by a generator of control emulation nmiuls that are also included in the control system. Switching circuits containing commutating co-identifiers 9-11 serve to lock in power thyristors. Three-phase load 12-14 is connected to the output of the inverter.

Pa figs. 2, a-e are given the timing diagrams of control pulses for thyristors 1-6, respectively, arriving during normal operation and the receiver from the hcp, in fig. 2, g and h - pulses, but the state of GK for thyristors 7 and 8, respectively, and in FIG. 2, and - l are the voltage forms on the capacitors 9-11.

Turning off the inverter of the power loss without using the proposed power method is as follows.

If, iairimer, the SMI was turned off at the moment / 1 (see Fig. 2). and the ledger some time after that, the current is carried out by the connecting switches 2--4. At the moment of the next imimage, the thyristor 7 is turned on, the thyristors 2 and 4 are switched off by the currents of the oscillating circuits, which include capacitors 9 and 11, and the thyristors 3 and 7 remain switched on for the following reason. Switching circuits have a high Q-value, and after recharging in the process of switching, co-sensors are charged before voltage, where E is the voltage of the avertor's power supply.

3

Capacitors 9 and 11 are charged up to the value of E along the contours shown in FIG. 1 arrows. Thus, the thyristors 7 and 3 remain turned on for as long as their holding current and time allow, determined by the capacitance of the capacitors and the load resistance 12-14. The next impulse applied to the thyristor 7 at time i does not change the state of the thyristors, and the subsequent impulse sent to the thyristor 8 at time t causes the inverter to drop out, since the thyristors 7 and 8 turn on.

If, however, the power supply unit and the main switchboard are turned off simultaneously, for example, at an arbitrary time t, then the inverter will not turn off, since the three power thyristors will remain on.

When turning off the inverter according to the proposed method, the processes proceed as follows.

Assume that the SMI was turned off at an arbitrary moment ti. At time t, the next impulse from the HA includes the thyristor 7, and the thyristors 2 and 4 are turned off. GCs are disconnected after the next control pulse of the switching thyristors, i.e., at time tz and up to the moment / 3 of the expected control pulse of the switching thyristors. Then the pulse at time t will not follow, the thyristor 8 will not turn on, and the inverter will not overturn.

four

The SMI can be turned off at the moment, then at the moment tz a pulse will follow that does not change the state of the thyristors, and at the moment / 4 the pulse also does not follow, since the HAs are turned off in the interval between tz and t.

Thus, according to the proposed method, the inverter is turned off without the help of switching devices in the power circuit. When implementing the method, the reliability of the inverter operation is increased, since no wear and burning of mechanical contacts occurs, as well as savings are achieved due to the exclusion of switching devices.

Subject invention

A method of disconnecting a three-phase autonomous inverter with a ground commutation, which consists in generating, by means of generators, control pulses of power and switching thyristors, characterized in that, in order to increase the reliability of operation, the generator of control pulses of switching thyristors is turned off in the time interval from the end of the next impulse that followed an arbitrary moment of switching off the generator of thyristor-induced regulation impulses until the moment of the expected subsequent impulse and commuting thyristors.

,,, L .1

 - | --fc22: fC

 I i "

...

; P.

W 1 W G1G; p

////// l

//////////// l

,,,,,,, „. ,,,,,,: ///////// M

ly

Rig.2