Three-level LLC converter and control method thereof

Abstract

The invention discloses a three-level LLC converter and a control method thereof. The three-level LLC converter comprises four direct-current input filter capacitors, four switching devices, a clamping capacitor, two filters, two transformers, two diodes and an output voltage stabilizing capacitor. The control method comprises the steps of output voltage fractional order control adjustment and driving signal generation. The three-level LLC converter has the advantages that the topological switch stress is small,; the voltage is half of the direct-current bus voltage; the three-level LLC converter is simple in structure, low in , the switching loss is low and capable of improvingthe system efficiency is improved, and, finally, the three-level LLC converter can achieve circuit input capacitor voltage self-balance, a large number of voltage sensors and a complex voltage balance control algorithm do not need to be added, and the three-level LLC converter is simple in system control structure and, has excellent anti-interference performance, steady state performance and dynamic performance and has engineering application value.

Description

technical field [0001] The invention relates to the technical field of converters, in particular to a three-level LLC converter and a control method thereof. Background technique [0002] With the rapid development of the power electronics industry, LLC converters are widely used, such as military power supplies, electric vehicle charging piles, new energy power generation systems, uninterruptible power supplies and smart grids. The LLC converter can implement soft switching technology, thereby eliminating switching loss, reducing electromagnetic interference, improving the conversion efficiency of electric energy, and realizing high system efficiency and high power density. However, the voltage regulation of the traditional LLC converter and its control method has a great dependence on the load conditions, which leads to the limitation of the output voltage range of the traditional LLC converter. In order to solve this problem, Wang Haoyu et al. published in IEEE Transactio...

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Problems solved by technology

[0003] In order to solve the above-mentioned problems in the prior art, the present invention provides a three-level LLC converter and its control method, which has the advantages of small switching stress, small switching loss, high system efficiency, and no need to increase a large amount of voltage In the case of sensors and complex voltage equalization control algorithms, the circuit capacitance can be self-balanced, and it has excellent immunity, steady-state and dynamic performance

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