Bridge arm number-adjustable high-capacity high-voltage-boosting three-level isolation type DC/DC converter

Abstract

The invention provides a bridge arm number-adjustable high-capacity high-voltage-boosting three-level isolation type DC / DC converter. If the converter is set to contain m bridge arms, 2m input phasesand n gain units, the converter is composed of a direct-current input voltage source, m bridge arms; wherein each bridge arm comprises four power switches and two diodes, a direct-current power supplyis connected to the upper side and the lower side of the bridge arm, and the two capacitors c1 are connected in parallel; 2m high-frequency transformers with ratio of transformation being 1: n including T1, T2, T3... T2m, n high-voltage boosting gain units on the right end of the transformers, a load RL, a filter capacitor C0 and a diode D0, wherein in each high-voltage boosting gain unit, a first gain unit contains 2m-1 capacitors and diodes, and other gain units contain 2m capacitors and diodes. Compared with an existing three-level converter, the converter has the advantages that input phase number of the converter can be freely adjusted, and the currents of all the input phases can be automatically equalized, so that the control strategy of the converter is simple, and the input and output gain is high and adjustable. The voltage and the current stress of a switching device are low and adjustable. The converter can be applied to high-capacity high-voltage boosting occasions needing electrical isolation.

Description

technical field [0001] The invention relates to a bridge-based large-capacity, high-boost DC / DC converter, in particular to a large-capacity, high-boost three-level isolated DC / DC converter with adjustable bridge arms. Background technique [0002] In recent years, offshore wind power DC confluence and transmission technology has received more and more research and attention due to the continuous expansion of wind farm scale and increasing offshore distance. The three-level inverter is considered to be a better choice for the input-side inverter circuit in the DC bus due to the low voltage stress of the switching device, but the current proposed scheme is limited by the problem that the number of input phases cannot be adjusted and the current stress of the device is too high . Traditional three-level inverters and diode bridge rectifiers are widely used, but on the one hand, the output voltage gain is often achieved by enlarging the turns ratio of the primary and secondary...

AI Technical Summary

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 stress of the voltage and current is too high, the gain of the input and output is low, and the voltage stress of the diode on the rectification side is high, the present invention provides a large inverter with an adjustable number of bridge arms. High-capacity step-up three-level isolated DC / DC converter

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