A Soft Switching Circuit Applicable to Voltage Type Quasi-z Source Inverter

Abstract

The invention relates to the technical field of power electronic conversion, in particular to a soft switching circuit suitable for a voltage-type quasi-Z source inverter, the voltage-type quasi-Z source inverter is powered by a DC power supply V DC , an impedance network, a soft switching circuit, an inverter bridge, a filter and an AC power grid or an AC load cascaded to form, the soft switching circuit is connected between the impedance network and the inverter bridge, and the soft switching circuit includes a resonant inductance L r , resonant capacitor C r , main power switch tube S C and its antiparallel diode D sc , Auxiliary power switch tube S al and its antiparallel diode D sal . The soft switching circuit can realize the soft switching of the direct-through bridge arm of the voltage-type quasi-Z source inverter, and reduce the switching loss of the direct-through state of the quasi-Z source inverter.

Description

technical field [0001] The invention relates to the technical field of power electronic conversion, in particular to a soft switching circuit suitable for a voltage-type quasi-Z source inverter. Background technique [0002] The quasi-Z source inverter has the advantages of single-stage buck-boost, simple structure, allowing bridge arms to pass through, continuous input current, small impedance network capacitor voltage stress, and no start-up current impact. It is suitable for applications in photovoltaics, wind power and other input voltages. Large new energy power generation occasions. When the working state of the quasi-Z source inverter is switched to the through state, the through bridge arm will bear a large current stress. If the opening of the straight-through bridge arm is hard opening, obviously a large switching loss will be generated. The switching loss of the direct bridge arm is an important part of the switching loss of the quasi-Z source inverter. Therefo...

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Problems solved by technology

[0004] The auxiliary resonant circuit in the series resonant soft switching circuit using active clamping soft switching technology is composed of an active switching device, a resonant inductor and a clamping capacitor, and the zero voltage of the switching tube is realized by adopting a new space vector modulation strategy The switch can suppress the reverse recovery process of the anti-parallel diode of the inverter bridge, and has the advantages of simple control, low hardware cost, and small voltage stress of the switch tube. However, the resonant inductance of this soft switching circuit is placed on the DC bus, which increases the The total loss of the auxiliary resonant unit is reduced; the other is a parallel resonant soft switching circuit with the help of coupled inductors. In the auxiliary resonant circuit, a coupled inductor with the same number of turns, an auxiliary switching tube and a blocking diode are used to realize the soft switching of the straight-through bridge arm. , there are problems such as complex topology of the resonant circuit, high hardware cost, large current stress of the auxiliary switch tube, and large loss

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