Resonant pole-type soft switching inverter circuit based on auxiliary commutation of transformer

Abstract

The invention relates to a resonant pole-type soft switching inverter circuit based on auxiliary commutation of a transformer. The main circuit comprises a DC power supply, a three-phase pulse width modulation inverter and a three-phase resistance-inductance load, wherein three groups of the same auxiliary resonant circuits are arranged between the DC power supply and the three-phase pulse width modulation inverter; the three groups of the auxiliary resonant circuits are corresponding to the A phase, the B phase and the C phase of a three-phase transformer; each resonant circuit group comprises one single-phase transformer, two auxiliary switches with antiparallel diodes, one resonant inductor and four auxiliary diodes. A large-capacity grading capacitor serially connected in a DC link is avoided, and the neutral point potential change problem of the inverter is solved; inductance and current thresholds related to control of auxiliary switches do not need to be set, and no extra detection and timing circuit is needed; and the transformer is used for auxiliary commutation, each phase of auxiliary circuit is only provided with two auxiliary switches, and the auxiliary switching device and the main switching device of the inverter can realize soft switching.

Description

technical field [0001] The invention belongs to the technical field of power electronics, in particular to a resonant pole type soft-switching inverter circuit for transformer auxiliary commutation. Background technique [0002] The current industrial production has higher and higher requirements for the switching frequency of the inverter, so high frequency will become the leading direction for the development of the inverter in the future, but in the hard switching inverter, the higher the switching frequency of the switching device, the higher the switching The loss will be greater, which seriously limits the development trend of high-frequency inverters. For this reason, soft switching technology has been developed rapidly. When the inverter is working at high frequency, soft switching technology can be used to realize the soft switching of the power switching devices in the inverter, thereby reducing the switching frequency of the power switching devices. losses and im...

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Problems solved by technology

[0004] Because of the excellent performance of the resonant pole inverter, it has been widely used in the industrial field. Various auxiliary circuit topologies have been proposed by researchers to promote the development of this type of inverter, but These topologies still have room for improvement

For example, Yao Gang and others disclosed "a new type of ZVS-ZCS inverter based on transformer-assisted commutation" in "Acta China Electrical Engineering Society" Volume 26, Issue 6, 2006. Four active auxiliary switches are used, which not only increases the volume and cost of the inverter, but also greatly increases the difficulty of controlling the inverter; Wang Qiang et al. Issue 27 disclosed "New Zero-Voltage, Zero-Current Resonant Pole Type Soft-Switching Inverter". Although the extension structure proposed in this article realizes the zero-current turn-off and zero-voltage turn-on of the main switch, the extension structure is in the DC bus. Two large-capacity electrolytic capacitors are connected in series to build the neutral point potential, so when the inverter works at high frequency, frequent charging and discharging of the capacitor will cause the neutral point potential to change, affecting the normal operation of the inverter; Chu Enhui and others published "Research on New Active Auxiliary Resonant Pole Inverter" in "Journal of Instrument and Apparatus", Volume 30, Issue 6, 2009. Although the extension structure proposed in this paper does not use large capacitors to share DC Bus voltage, there will be no problem of neutral point potential change, but the auxiliary switching device in this topology cannot achieve zero current shutdown

In addition, in the current literature on soft-switching inverters, either a large capacitor connected in series between the DC buses is used to share the DC bus voltage equally, or complex coupled inductors and corresponding magnetic flux reset circuits are required, and some in order to ensure the realization of Soft switching requires a separate detection circuit and peripheral control circuit, which not only complicates the main circuit, but also increases the difficulty of control

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