Control method based on adaptive hybrid rectification multi-switch resonance LLC converter

Abstract

The invention provides a control method based on an adaptive hybrid rectification multi-switch resonance LLC converter. The circuit is characterized in that the structure is simple, the number of required components is small under the condition that the same wide output voltage range is achieved, and the circuit comprises a capacitor unit, an inversion network, a resonance network, a high-frequency transformer, a rectification network and a pulse signal generation unit. According to the control method, fixed-frequency asymmetric pulse width (APWM) modulation is adopted, the switching frequency is fixed and equal to the resonant frequency, the conduction duty ratio of a switching tube is changed only through a pulse signal generation unit, smooth switching of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge inverter circuit and a voltage doubling rectifier circuit is achieved, and then ultra-wide output voltage regulation is achieved. And meanwhile, circulating current in the circuit is small, control is simple, and the size miniaturization of the transformer is facilitated.

Description

technical field [0001] The invention belongs to the field of power electronics, in particular to a control method based on an adaptive hybrid rectification multi-switch resonant LLC converter. Background technique [0002] In recent years, with the increasingly prominent problems of energy crisis and environmental pollution, clean energy applications such as new energy vehicles, wind power generation, and photovoltaics have ushered in a period of great development. Among them, DC-DC converters with electrical isolation play an important role in the above fields. play an indispensable role. At present, high conversion efficiency and high power density are the mainstream development directions of DC-DC converters. How to meet their voltage regulation requirements, high-frequency and high-efficiency operation, and miniaturization in different applications are the main research hotspots. [0003] Among a series of DC-DC converters, the LLC resonant converter has become a resear...

AI Technical Summary

Problems solved by technology

However, in applications that require a wide output voltage (such as electric vehicle chargers, lighting power supplies, distributed power distribution, etc.), pulse frequency modulated LLC resonant converters are difficult to achieve a wide voltage regulation range because their voltage gain is limited by the switching frequency.

Also, the use of frequency modulation complicates the converter design

In particular, when the switching frequency is far away from the resonant frequency, there will be a large circulating current in the circuit, and the switching tube cannot achieve zero-voltage turn-off (ZVS), and the diode on the rectifier side cannot achieve zero-current conduction (ZCS), which undoubtedly increases The switching loss of the conduction loss of the converter is reduced, and the energy conversion efficiency is very low

In addition, when working at a wide switching frequency, the low switching frequency corresponds to the volume and weight of the large transformer, which violates the miniaturization design of the converter and hinders the development of switching power supplies in the direction of high power density.

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