SU561267A1 - Consecutive multi cell inverter - Google Patents

Description

The invention relates to a power conversion technique and is intended to convert direct current into alternating current. Serial inverters are known, containing several cells connected in series 1, 2J. The disadvantage of these inverters is the dependence on the load voltage on the valves, which may exceed the input voltage of the converter. A serial multi-cell inverter is also known, containing an even number of series-connected capacitors connected to the input terminals via a smooth choke, a two-stroke inverter cell connected to each serial pair of which includes two groups of thyristors connected by counter, and commuting chokes and primary windings of the output transformer. However, the operation of such an inverter is dependent on the magnitude of the voltage on the valve X which may significantly exceed the input voltage. The aim of the invention is to limit the voltage on the valves. For this, the midpoints of the indicated capacitor banks and cells are interconnected, and the primary windings of the transformer are included J in the circuit of the gates of each cell. FIG. 1 shows a schematic diagram of the proposed inverter, see. 2 diagrams of voltages and currents of the main elements of the inverter. A series multi-cell inverter contains several cells of two-stroke inverters with counter-parallel connection of controlled and uncontrolled electric valves. Thyristors were used as controllable electric valves, and uncontrolled valves were used as diodes. Each cell contains thyristors 1.2 valves 3.4, capacitors 5.6, commutator .- chokes 7.8. Primary windings 9

transformer 10 is turned on with a switching 7.8 thyristors. 1.2. The midpoints of the capacitors 5.6 and TSipHciopoB 1p2 of each one are connected by each other. riociienoBaTd ibHO

The connected capacitors 5.6 of all the cells are connected via a smoothing choke 11 to the input terminals.

The device works as follows

In the initial state, all thyristors are turned off each; from the capacitors are charged to the voltage E / 2 | vl, where E is the input voltage, and N is the number of cells.

At time t, after the supply of the control pulse, the thyristor 1 is turned on. After turning on the thyristor 1 through the circuit 5.7-9. an oscillating current flows .1 j sinusoidal shape. At the time of t2 after changing the direction, Kai, the thyristor 1 turns off, and the Hz closes through the V-gate on the circuit 5-7 - 9 - 2 - 5. At this (L, the capacitor 5 is recharged. At the time of the switch, the oscillating current i becomes equal to zero, the valve 3 is turned off. In the time interval, the thyristor 1 restores the fading properties.

At the moment of time i nocne of the supply of the control pulse, the thyristor 2 turns on, at the same time the recharging of the capacitor 6 begins. The processes in the inverter proceed analogously when the thyristor 1 is turned on.

The alternate inclusion of the inverter thyristors provides a time shift of the current pulses of the oscillating circuit. When applying control pulses to thyristors with a shift in time equal to the period of natural oscillations of the commutation circuit, it is possible to obtain a continuous load current curve.

The tests performed on the proposed inverter showed that the maximum value of the alternating voltage at the input, capacitors and valves does not depend on the load and is 2 N times less than the input voltage.

Claims (3)

1. USSR author's certificate No. 299927, H P2 P 5/06, 1970. 2. The patent of France No. 2155821, MKL. H 02 M 5/00, 1970 .. 3.Berkovich E. I, et al. Thyristor High Frequency Converters L ,, Energie, 1973, p. 68-69, fig. 3 -28.