A bi-directional dc-dc converter mixed with llc and dab

Abstract

The invention discloses a bidirectional DC-DC converter mixed with LLC and DAB, which comprises an H-bridge circuit, two LLC resonant cavities, two isolation transformers with the same conversion ratio and a three-phase half-bridge full-control circuit; , the two ends of the H-bridge circuit and two series-connected split resonant capacitors are connected to both ends of the input power supply, the original side of the isolation transformer with the same name is connected to one end of the resonant inductor of the resonant cavity, and the other end of the resonant inductor is connected to the neutral point of the half-bridge of the H-bridge circuit , the same-named end of the secondary side of the isolation transformer is connected to the neutral point of the bridge arm of the three-phase half-bridge full-control circuit; the non-identical end of the two isolation transformer secondary sides are connected to the neutral point of the bridge arm of the three-phase half-bridge full-control circuit. The invention utilizes the advantages of LLC frequency conversion and voltage regulation and DAB phase-shift voltage regulation, combined with PWM pulse 180º phase-shift to realize fast switching between LLC and DAB, realizes optimal control of efficiency under different load rates or voltage gains, has small switching loss, high efficiency, The advantage of simple structure.

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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