Isolated high-frequency resonant DC-DC converter with wide output voltage range and method

Abstract

The invention discloses an isolated high-frequency resonant DC-DC converter with a wide output voltage range and a method thereof. The converter includes: a full-bridge circuit on the primary side and a rectifier circuit on the secondary side; the rectifier circuit includes four Switching elements, two capacitors and a switching device S, and the primary side and the secondary side are connected through a transformer and an LC series resonant cavity; the isolated DC converter of the present invention is suitable for battery charging and renewable energy power generation , can realize output voltage 1-2 times or 1-4 times adjustment, overcome the defect that the series resonant converter cannot adjust the voltage in a wide range, and meet the wide range adjustment of the output voltage when charging the battery / supercapacitor and the high transformation ratio of renewable energy power generation demand. The voltage regulation is realized through the conduction duty cycle of the secondary side switching device, instead of using the resonant cavity for frequency conversion and voltage regulation, so that the converter has high efficiency in the entire voltage regulation range.

Description

technical field [0001] The invention belongs to the technical field of converters, and relates to an isolated high-frequency resonant DC-DC converter with a wide output voltage range and a method. Background technique [0002] For a long time, unidirectional DC converters have been a research hotspot in the direction of power electronics. In recent years, the application of distributed power generation and the popularization of electric vehicles have put forward new requirements for DC converters. Household electric vehicles, urban train batteries or supercapacitor charging require a wide range of output voltage changes. In distributed power generation systems such as photovoltaic power generation or offshore wind power, the voltage will fluctuate greatly due to the influence of natural conditions such as sunlight and wind strength. Therefore, DC converters with a wide voltage range have become a research hotspot. [0003] The DC converter is divided into isolated type and ...

AI Technical Summary

Problems solved by technology

The forward converter is obtained by adding a transformer to the topology of the BUCK converter. Its topology has inherent defects, and an additional magnetic core reset circuit needs to be designed; there is only one switch tube in the flyback converter, and the structure is simple, but its switch The voltage stress of the tube is large, which is suitable for applications with low power and multiple outputs; the output voltage characteristics of the push-pull converter are good, and it can be regarded as two forward converters working alternately, but the circuit has the problem of unidirectional magnetic bias; DAB is considered to be the core converter of the next-generation medium and high voltage power system. Its topology itself has the characteristics of ZVS, but its switch tube is turned off at the peak current, and the efficiency of the converter is affected due to the large turn-off loss when the operating frequency is high. , and the voltage regulation capability is insufficient; due to the effect of the resonant cavity, the series resonant converter can achieve ZVS and the turn-off loss is small, but it can only work in the step-down mode; the LLC resonant converter has high efficiency and has certain regulation voltage capability, but its high efficiency characteristics are only near the resonant operating point, and the efficiency decreases in a wide voltage range

In general, the existing DC converters cannot achieve a wide voltage regulation range with high efficiency

Images