Large-capacity isolated DC/DC converter based on multi-phase three-level inverter

Abstract

Disclosed is a large-capacity isolated DC/DC converter based on a multi-phase three-level inverter. If the converter is configured to comprise 2m input phases, m bridge arms and n gain units, the converter consists of a DC input voltage source, m bridge arms, 2m high-frequency transformers T1, T2, T3...T2m having a transformation ratio of 1: k, n gain units, an output filter capacitor C0, an output diode D0 and a load RL, wherein each bridge arm comprises four power switches and two diodes, and a DC power supply is connected in parallel to the upper and lower sides of the bridge arms. Amongthe gain units, the gain unit 1 comprises (2m-1) capacitors and (2m-1) diodes, and the gain unit 2 to the gain unit n respectively comprise 2 m capacitors and 2 m diodes. Compared with the existing three-level isolated DC/DC converter, the number of the bridge arms can be adjusted freely, the current of each bridge arm is automatically equalized, the voltage stress and current stress of all switches and diodes are significantly reduced and adjustable, and the input and output gains are high and also adjustable, so the converter is suitable for large-capacity and electrically isolated input andoutput applications.

Description

Technical field [0001] The invention relates to a DC-DC converter, in particular to a large-capacity isolated DC / DC converter based on a multi-phase three-level inverter. Background technique [0002] In recent years, the problem of energy depletion and environmental pollution has become increasingly severe. The development of offshore wind resources has important practical significance. Large-capacity and long-distance offshore wind power is the future development trend of wind power. Because the traditional AC convergence has many disadvantages such as frequency synchronization and high harmonic content, the offshore wind power DC convergence method has received more and more research and attention. The three-level inverter is considered to be a better choice for the input side inverter circuit in the DC confluence due to the low voltage stress of the switching device. The traditional three-level inverter and the diode bridge rectifier are widely used, but on the one hand, its ...

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Problems solved by technology

[0003] In order to solve the problems in the prior art that the number of input phases of the three-level inverter cannot be adjusted, the voltage and current stress is too high, the input and output gain is low, and the voltage stress of the diode on the rectification side is high, the present invention proposes a multi-phase three-level inverter based on Large-capacity isolated DC / DC converter for transformer

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