Resonant DC link three-level soft switching inverter circuit

Abstract

The invention discloses a resonant DC link three-level soft switching inverter circuit which has advantages of simple structure and convenient control. The resonant DC link three-level soft switching inverter circuit comprises the components of: a DC power supply, an auxiliary resonance circuit, a diode clamp type three-phase three-level pulse width modulating inverter and a three-phase resistance inductive load. The auxiliary resonant circuit comprises the components of: four electrolytic capacitors with voltage dividing function, six auxiliary switches, six diodes, two resonant capacitors and two resonant inductors. When switching of a three-level inverter main switch is required, the end voltage of a resonant capacitor Cr1 is reduced to zero through resonance between the resonant capacitor Cr1 and a resonant inductor Lr1, or the end voltage of a resonant capacitor Cr2 is reduced to zero through resonance between the resonant capacitor Cr2 and the resonant inductor Lr2, thereby realizing zero voltage switching of the main switch. The resonant DC link three-level soft switching inverter circuit realizes a target of expanding a resonant DC link soft switching topology structure into a diode clamp type three-phase three-level inverter, and furthermore has the functions of: reducing number of auxiliary switching devices, reducing hardware cost and facilitating control.

Description

Technical field: [0001] The invention relates to the technical field of power electronics, specifically, it is a resonant DC link three-level soft-switching inverter circuit. Background technique: [0002] Compared with the traditional two-level inverter, the three-level inverter has the advantages of reducing the voltage stress of power devices, reducing electromagnetic interference and output voltage harmonic content, etc. This technology is increasingly used in high-voltage large power occasions. In recent years, high-voltage and high-power three-level inverters have become a research hotspot in the field of power electronics. When the three-level inverter is used in high-voltage and high-power applications, the blocking voltage and current flowing through the switching devices are relatively large. With the increase of switching frequency, the switching loss of the three-level hard-switching inverter will also increase significantly, greatly reducing the efficiency of ...

AI Technical Summary

Problems solved by technology

When the three-level inverter is used in high-voltage and high-power applications, the blocking voltage and current flowing through the switching devices are relatively large. With the increase of switching frequency, the switching loss of the three-level hard-switching inverter will also increase significantly, making the efficiency of the inverter greatly reduced

When the three-level inverter works in the hard switching state, the high voltage change rate and current change rate will also cause serious electromagnetic interference

Wu Hongyang and others disclosed "a passive resonant pole type three-level soft-switching inverter circuit" in the "Chinese Journal of Electrical Engineering" 2002, Volume 22, No. 10. There is no auxiliary switching device in this circuit. Compared with The three-level hard-switching inverter circuit can effectively reduce switching loss and improve efficiency by only adding passive components such as inductors, capacitors, and diodes. Higher than switching devices in three-level hard-switching inverters, increasing voltage stress on switching devices

Fan Zichao and others disclosed "an auxiliary resonant conversion pole type three-level soft switching inverter circuit" in "Journal of Electrotechnical Society" 2006, Volume 21, Issue 5. The control of the auxiliary circuit and the control of the inverter are completely independent , the soft switching operation of the main switching tube is not affected by the load conditions, the resonant inductance is separated from the main power path, and it is easy to introduce into multi-level circuits. It has become the most promising solution for high-voltage, large-capacity, and high-frequency inverters. However, when this topology is applied to a three-phase three-level inverter, there are as many as 12 auxiliary switching devices, the control is complicated, and the hardware cost is relatively high.

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