SU955452A2 - Inverter - Google Patents

Description

(54) INVERTER

one

The invention relates to a converter technique and may find wide application in the technique of induction heating and in other high-frequency devices with a smooth control of output power.

According to the main author. St. No. 838968 is well known for an inverter that contains two thyristor bridges connected to the input terminals through a filter choke, connected in series with each other via commutating chokes and a chain of two series-connected filter capacitors, whose common point is connected to the first output pin, and the connecting point of the choking chokes to the second output output, as well as cut-off diodes connected by the same electrodes to the thyristor bridges of the same name, connected to the commutating throttles, and about is provided with two throttle magnitosv-bound E, one ends of which are connected to other electrodes of cutoff diode, and the other ends thereof are connected to the respective ends of said chain of two capacitors. In the process of operation of this high-frequency inverter, the voltage of the switching capacitor of one of the bridges, recharging it through the switching throttle and the load, when the total voltage on the filter capacitors is reached, opens the cutting diodes. The energy stored in the switching choke is transferred by the filter capacitor through magnetically coupled chokes, which significantly reduces the speed of the current and the amplitude of the current through the cutting diodes at which the current is broken. When the thyristors of the antiphase bridge are switched on, the current through the load flows in the opposite direction 1.

The disadvantage of the inverter circuit is that it is impossible to control the power in the load from zero to the nominal value at a constant input voltage and low reliability.

The purpose of the invention is to provide control of power in the load from a zero nominal value and increase the reliability of the device.

The goal is achieved by the fact that the inverter is equipped with an additional capacitor, two diodes, two throttles and two thyristor bridges connected in series with each other via additional chokes and connected to filter capacitors, with the additional diodes connected by one electrode to the points of additional chokes and thyristor bridges, and other electrodes - to the same electrodes of the cutting diodes and the plates of the additional capacitor, and the connection point of the additional The choke is connected to the second output pin.

The drawing shows a diagram of the inverter.

The inverter contains a filter choke 1, thyristor bridges 2-5, each consisting of thyristors 6-9 and switching capacitor 10 in the diagonal and connected in pairs sequentially through switching chokes 11, 12 and additional chokes 13, 14; the load 15, which is connected between the connection point of the filter capacitors 16, 17 and the common point of the indicated chokes, cut-off diodes 18, 19 and additional diodes 20, 21 connected by electrodes to the thyristor bridges, includes magnetically connected chokes 22 and 23, alone of the terminals of which are connected directly to the filter capacitors 16 and 17, and the additional capacitor 24 is connected to the connection points of the like terminals of the diodes 18-21.

The operation of the high-frequency inverter at rated power in the steady state mode is carried out as follows.

First, control pulses are applied to thyristors 6, 8 of bridges 2, 5 and their switching capacitors 10 are recharged through the indicated thyristors, switching inductors 11, 13, load 15 and filter capacitor 16. The current flows through the load in the direction indicated by the arrow. When the voltage on the switching capacitors 10 is equal to the total voltage of the power source on the capacitors 16 and 17 of the filter, by including in the circuit of magnetically coupled chokes 22 and 23, all the diodes 18-21 are included and the energy stored in the x 11 and 13 is transferred to the capacitors 16 and 17 filters. The next moment control pulses are applied to thyristors 6 and 8 of bridges 3 and 4 and their switching capacitors 10 are recharged through the indicated thyristors, chokes 12, 14, load 15 and filter capacitor 17. The current in the load flows in the opposite direction indicated by the arrow. With

the voltage on the switching capacitors 10, equal to the total voltage of the power source on the capacitors 16 and 17 of the filter, due to the inclusion in the circuit of matnized connected chokes 22 and 23, include

All diodes 18-21 and energy stored in throttle x 12 and 14 are transferred to filter capacitors 16 and 17. Then control pulses are applied to thyristors 7, 9, bridges 2, 5, and the processes are repeated. Then served

thyristor control pulses 7, 9, bridges 3, 4, and the processes are repeated. For smooth control of power in the load from nominal to zero, the moments of applying control pulses to the thyristors of bridges 3 and 5 are smoothly shifted

in phase with respect to the moments of the supply of control pulses to the thyristors of bridges 2 and 4. In this case, the magnitude of the current flowing through the load and, consequently,

MouiHOCTb in load. With a phase shift of 180 e. hail, alternating current is closed through the filter capacitors 16, 17 and thyristor bridges, and does not leak through the load, and the power delivered to it is zero. Thus, an extension of the functionality of the proposed inverter is achieved. During the operation of the inverter, at the moments of switching its valves, the capacitor 24 damps the arising overvoltages, due to which an increase in the reliability of the device is achieved.

Claims (1)

1. USSR author's certificate No. 838968, cl. H 02 M 7/515, 1979.