SU1464273A1 - Push-pull transistor inverter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply systems. The purpose of the invention is to expand the operating range of load currents. The two-step transistor inverter contains an output-transform ator 1, power transistors 2, 3, a control unit and fixed delay nodes 6, 7. Parallel to the primary winding of the output transformer, a series capacitor 5 is connected in series and a second capacitor 8, shunted by an AC switch 9, is controlled e. Mym from the output of the current sensor 10. When. The load currents close to the no-load current, the energy accumulated in transformer 1, is not enough to recharge the first capacitor 5 to a voltage of 211 ,, which leads to an increase in current through the power transistors 2, 3 when switched on and loss of power. Therefore, when the load current decreases, the AC key 9 is opened and the second capacitor 8 is connected in series with the first capacitor 5 and their total capacitance decreases. 1 il. (Oh (L

Description

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The invention relates to electrical engineering and can be used in secondary power supply systems for converting a constant voltage to an alternating voltage.

The purpose of the invention is the expansion of the operating range of load currents.

The drawing shows the scheme of the proposed inverter.

The inverter includes an output transformer 1, power transistors 2 and 3, a control unit 4 and a first capacitor 5. The outputs of the control unit 4 are connected to the control inputs of the power transistors 2 and 3 through the fixed delay nodes 6 and 7. The first capacitor 5 is connected in parallel to the primary winding of the transformer 1 through the second capacitor 8, shunted by the AC switch 9. Current sensor 10 is connected in series to the power input circuit | inverter. The control input of the alternating current key 9 is connected to the output of the current sensor 10 through the threshold element 11. A load 12 is connected to the output of the inverter. The inverter operates as follows.

If the load current is equal to the nominal value, then a signal is output at the current sensor output, which through the threshold element 11 switches on the alternating current key 9, and the capacitor 5 is connected in parallel to the primary winding of the transformer 1. It has capacitor 5 selected from the condition. minimum losses in transis-2 and 3 when switching at rated load current. When reducing the load current, especially in

close to idle, the energy accumulated in transformer 1 is small and capacitor 5 can not be recharged to voltage 211 in the fixed delay interval, which leads to an increase in current through transistors 2 and 3 at the moment they are turned on. Therefore, when the load current decreases, the capacitor 8 is connected in series with the capacitor 5 by means of elements 9-11, reducing the total capacitance of the chain connected in parallel to the primary winding of the output transformer 1, to such a value that the power loss during switching of the power transistors 2 and 3 in this mode are minimal.

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Claims (1)

20 Formula izbre.teni A push-pull transistor inverter containing an output transformer, the first terminal of the primary winding of which is connected to the first terminal of the first capacitor, and a control unit, the outputs of which are connected to the input circuits of the inverter power transistors through the fixed-delay nodes, in order to extend the operating range currents, entered the AC key, the second capacitor, the current sensor and the threshold element, and the second capacitor is connected between the second end of the primary winding output The leg of the transformer and a second terminal of the first capacitor and AC bypassed key, the control input of which via a threshold element connected to the output of current sensor connected in series in the input circuit of the inverter vshodov.