Phase shift compensation interleaved three-level LLC resonant converter

Abstract

The invention discloses a phase shift compensation interleaved three-level LLC resonant converter, and belongs to the technical field of power electronic converters. The converter includes an input power supply, two three-level LLC resonant circuits, two center-tapped transformers, two rectifier circuits, and an output circuit; and each three-level LLC resonant circuit comprises an input voltage dividing capacitor, a switch bridge arm and a resonant cavity which are connected in sequence. The converter provided by the invention can achieve a wide range of inputs, and also can compensate for the unsynchronized switching frequencies of the two circuits due to parameter errors by adjusting the duty cycle via the phase shift adjustment module. The two circuits are enabled to work at the same switching frequency without adding any auxiliary circuit through the interleaved structure, the output ripple is reduced, the converter efficiency is improved, and the service life of the power supply is prolonged.

Description

【Technical Field】 [0001] The invention belongs to the technical field of power electronic converters, and in particular relates to a phase shift compensation interleaved parallel three-level LLC resonant converter. 【Background technique】 [0002] In recent years, with the increasingly serious problems of energy crisis and environmental pollution, more and more scholars have begun to pay attention to new energy technology. In particular, how to use electric energy efficiently has become one of the current research hotspots. However, new energy power generation units are affected by climate change. The influence of conditions and weather is great, the output electric energy is unstable and discontinuous, and the output voltage has a wide variation range. Therefore, in order to adapt to a wide range of inputs, the three-level LLC resonant converter has become a research focus in the industry. [0003] When inputting in a wide range, the output current ripple of the single-channel thr...

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Problems solved by technology

[0003] When inputting in a wide range, the output current ripple of the single-channel three-level LLC resonant converter is large, and when it works in discontinuous mode, the secondary side cannot achieve zero-current shutdown, which will also cause large output current ripple

[0004] In order to meet the output current ripple, the capacitor ripple current can be reduced by increasing the operating frequency, but this will affect the efficiency of the converter; a lot of large capacitors can be connected in parallel for filtering on the secondary side, otherwise the output capacitor will be damaged Severe heat generation will affect the life of the power supply, but this will increase the size of the converter; an inductor filter can be used to reduce the current ripple at the output terminal, but the secondary side of the transformer will lose the ability of ZCS

Therefore, the interleaved parallel technology can be used, but the parameter error of the resonant components makes it difficult to share the current when the three-level LLC resonant converter is interleaved and paralleled. An additional control loop can be added to control the two-way current sharing, which will make the circuit design more complicated; The output current can also be regulated by frequency control, but the optimum operating point of the converter is determined by the designed parameters, and this method cannot strictly regulate the output voltage to achieve a wide range of input

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