Bidirectional zero-voltage switch modulation method of single-phase DC-AC converter

Abstract

The invention discloses a bidirectional zero-voltage switch modulation method of a single-phase DC-AC converter. The modulation method comprises the steps of judging a current converter working mode according to a product of a voltage and a current of a power grid; inputting a modulation wave subjected to sine pulse width modulation after full-wave rectification to a forward or reverse zero-voltage pulse module by a selective switch; selecting a forward zero-voltage pulse module when the converter works in an inversion mode; selecting a reverse zero-voltage pulse module when the converter works in a rectification mode; inputting the modulation wave to the forward or reverse zero-voltage pulse module and then generating a bridge arm short-circuit signal and an auxiliary switch signal; and acting the short-circuit signal onto a main switch during conversion period of the converter, and providing a freewheeling loop for magnetization of a resonant inductor so as to provide enough resonantenergy. The converter is simple in structure, zero-voltage connection of all switch devices in inversion and rectification modes are achieved, the switch loss is low, the circuit efficiency is high,a diode can be prevented from being reversely recovered, and the electromagnetic interference is reduced.

Description

technical field [0001] The invention relates to a soft-switching converter and its modulation technology, in particular to a bidirectional zero-voltage switching modulation method of a single-phase DC-AC converter. Background technique [0002] Single-phase DC-AC converter is a device that converts direct current into single-phase alternating current. The common topology is full-bridge topology, which can realize bidirectional flow of energy. The circuit works in a hard switching state, there is a diode reverse recovery phenomenon, and the switching loss of the device is large, which limits the increase of the operating frequency, reduces the circuit efficiency and has electromagnetic interference. The resonant DC bus soft switching technology is applied to single-phase DC-AC converters, which can realize zero-voltage switching of devices and reduce switching losses. In the forward inverter mode and reverse rectification mode, the amplitude of the AC current changes greatly...

AI Technical Summary

Problems solved by technology

In the forward inverter mode and reverse rectification mode, the amplitude of the AC current changes greatly with the phase, and it is difficult for the ordinary sinusoidal pulse width modulation method to achieve bidirectional full-range soft switching.

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