SU577630A1 - Semi-bridge inverter - Google Patents

Description

one

The invention relates to the field of converter technology and can be used in power supply systems for converting a high voltage constant voltage level to an alternating voltage.

Inverters are known that contain controllable switches and an OUTPUT transformer, in which chains of series-connected transistors or converter cells 1 are used to operate at higher input voltages.

The simplest such cell is a half bridge cell containing two arms of controlled keys and one capacitor 2.

The disadvantage of the inverter consisting of series-connected cells is the unevenness of the voltage distribution of the power source due to the different temporal characteristics of the transistors in the cells and the internal resistances of the cells. Therefore, the input voltage of the inverter has to be limited at a level lower than the product of the allowable voltage of one cell and the number of all cells.

The purpose of the invention is to expand the range of input voltages by more

uniform voltage division on controlled inverter keys.

This is achieved by introducing a chain of four consistently-connected diodes, including a parachute chain of four consistently-connected controlled keys between the input supply terminals of the inverter. Moreover, the midpoints of these chains are interconnected, the connection points of the respective extreme pairs of diodes and keys are interconnected via the primary and auxiliary windings of the output transformer, and the connection point of the lower pair of diodes is connected to the connection point of the upper key pair via a capacitor.

The drawing shows the proposed inverter, in which transistors are used as controllable keys.

Claims (2)

The inverter contains a chain of four according-series-connected transistors connected between the input supply terminals 5 and 6 of the inverter, and a chain of four according-series-connected diodes 7-10. The middle points of the strings are interconnected. The connection point of the diodes l9 and 10 is connected through the primary winding 11 of the output transformer 12 to the connection point of transistors 3 and 4, and the connection point of the diodes 7 and 8 through the additional winding 13 is connected to the connection point of transistors 1 and 2. Between the connection point of diodes 9 and 10 and the junction point of the transistors 1 and 2 include a capacitor 14. The windings 11 and 13 have the same number of turns and are connected in opposite directions to each other. The secondary winding 15 is connected to the load 16 of the inverter. The inverter works as follows. In accordance with the diagrams of control voltages Uj, transistors 1 and 4 are open in one half period, and transistors 2 and 3 in the other half period. If transistors 1 and 4 are open, the current from pin 5 passes through transistor 1, the capacitor 14, the primary winding 11 of the transformer and the transistor 4 charge the capacitor. All input voltage is applied to transistors 2 and 3. After a half-period of the output frequency, transistors 1 and 4 close and open transistors 2 and 3. Top of the capacitor 14 across the transistors 2 and 3 is connected to the lower end of the primary winding 11. Since the duration of the half periods is the same, the voltage across the capacitor 14 and the winding 11 is equal to half the input voltage (). In the period when transistors are open; 1 and 4, a voltage of the winding 11 is applied to the closed transistor 3 through the diode 9. At this time, the voltage W indicated on the diagram without brackets is generated on the winding W. This voltage, also equal to i% / 2, is applied through diode 8 to the closed transistor 2. After the transistors 1 and 4 are locked, transistors 2 and 3 are opened, and on the windings 11 and 13 a voltage is generated, the polarity of which is shown in parentheses. At this time, the voltage of the winding 13 through the diode 7 is applied to the closed transistor 1, and the voltage of the winding 11 through the diode 10 to the transistor 4. The diodes 8 and 9 are locked and the reverse voltage of the windings 11 and 13, respectively, is applied through the open transistors 2 and 3. Thus, the voltage applied to all elements of the inverter is half the input voltage, regardless of the frequency characteristics of the transistor. Claims of the invention A half-bridge inverter, containing four controllable switches, connected in a sequential chain, which is connected between the output terminals of the inverter, and a capacitor and an output transformer associated with them, characterized in that, in order to expand the range of input voltages, a chain is introduced of four consecutively connected diodes, connected in parallel to the specified chain in the opposite polarity with respect to it, with the middle points of the chain of controlled keys and the chain of diodes with interconnected, the connection point of one pair of diodes is connected through the primary winding of the output transformer to the connection point of one pair of controllable keys and through a capacitor to the connection point of another pair of controllable keys, and the connection point of the other pair of diodes is connected through an additional winding of the output transformer to the connection point of another pair of controllable keys. Sources of information taken into account in the examination: 1. US Patent No. 3373398, cl. 211-27, 1968. 2. MOIN B.C., Laptev NN. Stabilized transistor converters, Energia, 1972, p.442, fig.11-92.