LLC and DAB hybrid bidirectional DC-DC converter

Abstract

The invention discloses an LLC and DAB hybrid bidirectional DC-DC converter. The converter comprises an H-bridge circuit, two LLC resonant cavities, two isolation transformers with the same transformation ratio and a three-phase half-bridge full-control circuit. The two ends of the H-bridge circuit and two serially connected split resonant capacitors are connected with two ends of an input end power supply, primary dotted terminals of the isolation transformers are connected with one ends of resonant inductors of the resonant cavities, the other ends of the resonant inductors are connected with the neutral points of the half-bridges of the H-bridge circuit, secondary dotted terminals of the isolation transformers are connected with the neutral points of the bridge arms of the three-phase half-bridge full-control circuit, and the non-dotted terminals of the secondary sides of the two isolation transformers are connected with the neutral points of the bridge arms in the three-phase half-bridge full-control circuit. The advantages of LLC frequency conversion voltage regulation and DAB phase shift voltage regulation are utilized and combined with PWM pulse 180-degree phase shift to achieve LLC and DAB rapid switching, efficiency optimization control under different load rates or voltage gains is achieved, and the advantages of small switching loss, high efficiency and simple structure are achieved.

Description

technical field [0001] The invention relates to a bidirectional DC-DC converter mixed with LLC and DAB, belonging to the technical field of converters. Background technique [0002] In recent years, due to the excellent characteristics of voltage conversion, power quality conversion, noise and volume, etc., power electronic transformers are receiving widespread attention and will gradually replace traditional transformers. As a key link of power electronic transformers, isolated DC / DC converters are the focus of many research results. Among them, the converters with LLC resonant converters and DAB converters as the main topology are research hotspots. These two kinds of converters have soft switching capability while ensuring high-voltage power conversion and isolation, so the switching frequency can be very high. Currently, the switching frequency of new silicon carbide or GaN devices has reached MHz level. Among them, the LLC type resonant converter can guarantee the soft...

AI Technical Summary

Problems solved by technology

Among them, the LLC type resonant converter can ensure the soft switching working state in the whole load range, and has the ability of constant voltage regulation, but its variable voltage range is limited

Although the DAB converter has a large voltage transformation capability, because there is no direct relationship between its output voltage and the phase shift angle of the corresponding bridge arms, it is difficult to control light-load soft switching and requires a more complex control system to cooperate with it. This undoubtedly increases the complexity of the overall module of the converter and reduces the reliability of the system

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