SU706911A1 - Dc-to-ac converter - Google Patents

Description

(54) CONSTANT VOLTAGE TRANSMITTER TO VARIABLE

one

The invention relates to radio engineering, in particular to powerful power sources.

At higher voltages of the power supply, when the voltage applied to the shoulder of the switching node of the converter main body exceeds the value allowed for the transistor, a series connection of transistors or converter cells is used. Therefore, when the power supply voltage is high, it is advisable to serially connect the converter cells.

Known transducer with series connection, inverter cells 1

The main disadvantage of this converter is the presence of large switching losses due to the different resorption times of the transistors. At the moment of commutation, due to the difference in the absorption time, one of the cells may close later than the others, so the pulse power will be removed from it, equal to the total power of the entire converter. It is unacceptable .

The closest to the proposed technical entity is a converter of direct voltage into overflow 2, containing n inverter cells, the primary windings of which are located on the common core of the output transformer, and n-1 equalizing two-winding transformers, the windings of each of which are connected in series with the primary windings of the neighboring cells. Equalizing transformers eliminate the possibility of various currents flowing in cells in the switching mode. The disadvantage of this device is that the voltage on one cell can rise above the voltage on another cell, 4Tq, in turn, can lead to the failure of this cell.

The aim of the invention is to increase the reliability of the converter.

This goal is achieved by the fact that the voltage to AC converter contains n inverter cells, the primary windings of which are located on the common core of the output transformer and n-1 equalizing two-winding transformers, the windings of each of which are connected in series with the primary windings of neighboring cells, and one of the windings each equalizing transformer is shucked with a resistor.

The drawing is a diagram of the proposed Converter with two inverter cells.

The proposed yctpoficTBo works as follows.

The transistors G-8 of two bridge inverter cells, under the action of a control signal, alternately connect the primary windings of transformers 9, 10 to either "plus, then" to minus, so that alternating current of rectangular form flows into the winding Xg.

The primary windings of the power transformer 9 are connected according to, so the magnetic fluxes are summed. In the equalizing transformer, the windings are switched in opposite, therefore the magnetic fluxes are subtracted.

In order to equal the voltages on the transforming cells, it is necessary that the voltage on the equalizing transformer be close to zero.

In the case where the absorption of transistor 1 (or 6) is less than the absorption of transistor 3 (or 8), transistor 1 (or 6) is turned off earlier than transistor 3 (or 8). The current in the first converter cell stops, which means that the current in the corresponding winding of the equalizing transformer 10 is discontinued. For the second conversion transformer cell, at this moment, the equalization transformer is an active resistance. Thus, the current of the second converter cell decreases sharply and there will be no overload.

The need for a resistor 11 in the winding of the control transformer is determined by the following condition.

The voltages on the converter cells are equal respectively

, Ui ± g40

1b Ui.y2, where 1 / | - voltage at primary winding

power transformer 9; 1/2 is the voltage on the windings of the equalizing transformer 10. Thus, on one cell the voltage converter can be greater than the second, with equal voltages on the primary windings of the power transformer.

Through an equalizing transformer, the energy is transformed from a cell with a higher voltage into a cell with a lower voltage. In the limit, on one cell, the voltage may be double, and on the other - equal to zero.

On the resistor 11, the power is dissipated due to the voltage, this leads to the fact that the power consumed from the first cell decreases, therefore, the voltage across it decreases, and the second cell increases, i.e. the voltage on the cell is equalized and the system tends to cause the voltage on the equalizing transformer to be zero.

Resistance of resistor 11 should be

K Rf mln (n-l),

where t is the resistance of the load, reduced to the primary winding;

n ... 77 is the number of converters

cells)

but not more than the value determined by the uncontrolled currents of the transistors, the allowable inequality L, .. and Ca

For the minimum difference C |. | ... and C, .. Re Kmtt .. (p-1),

Cell control can be performed from master oscillator 12.

Claims (2)

1. Moin V.S. and Laptev N.N. Stabilized transistor converters. IA., “Energy, 1972. 2. USSR author's certificate number 612367, cl. H 02 M 7/537, 1976.