Tri-level bidirectional DC/DC circuit

Abstract

The invention relates to a tri-level bidirectional DC / DC circuit. The circuit comprises an MOSFET tube M1, an MOSFET tube M2, an MOSFET tube M3, an MOSFET tube M4, a flying capacitor, a diode and an inductor. The drain electrode of the MOSFET tube M1 is connected with the positive electrode of a cell. The drain electrode of the MOSFET tube M2 is connected with the source electrode of the MOSFET tube M1. The source electrode of the MOSFET tube M2 is connected with the negative electrode of the cell. The source electrode of the MOSFET tube M3 is connected with the drain electrode of the MOSFET tube M1. The source electrode of the MOSFET tube M4 is connected with the drain electrode of the MOSFET tube M3. The drain electrode of the MOSFET tube is connected with one end of a direct-current bus. One end of the flying capacitor is connected with the drain electrode of the MOSFET tube M3. The other end of the flying capacitor is connected with the source electrode of the MOSFET tube M1. The source electrode of the MOSFET tube M1 is connected with the middle point of the direct current bus through the inductor and the diode. The other end of the direct current bus is connected with the source electrode of the MOSFET tube M2. According to the invention, a low-voltage grade MOSFET can be used for replacing a high-voltage grade MOSFET, so the disadvantage of the quite poor performance parameters of the high-voltage MOSFET device is overcome; switching loss of the switch tube can be reduced; and the switch tube can be prevented from being damaged.

Description

technical field [0001] The invention belongs to the technical field of power electronic converters, and relates to a three-level bidirectional DC / DC circuit, which is suitable for power electronic equipment requiring bidirectional flow of energy, such as photovoltaic energy storage inverters and charging piles. Background technique [0002] At present, there are more application requirements for charging and discharging high-power batteries. Using three-phase electricity to charge batteries and using high-voltage batteries for energy storage has become a better solution. This means higher battery input voltage and higher bus voltage for photovoltaic energy storage inverters. In order to be compatible with mainstream three-phase grid-connected inverters, the maximum bus voltage needs to reach 1000V. To use the traditional Buck-Boost circuit, it is necessary to select a semiconductor switching tube device with a withstand voltage level of 1200V. In order to minimize the equi...

AI Technical Summary

Problems solved by technology

However, when the inductance is commutated, the synchronous rectification MOSFET has poor body diode characteristics and large junction capacitance, causing the synchronous rectification MOSFET to have a reverse current flow when it is turned off.

This reverse current will cause a large loss, and more seriously, it will cause a large voltage spike at the drain-source of the MOSFET, which will cause overvoltage damage to the MOSFET

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