In order to solve the problems that LLC resonant converter has too large breaking loss,narrow gain range and unstable output under wide input,a wide gain resonant converter with changing mode was researched.The converter and its control strategy can freely switch between full bridge and half bridge ac-cording to the input voltage,effectively expanding the voltage gain range.Moreover,the gain range can be further widened by optimizing the resonator structure to reduce the energy cycle and switch loss.The third harmonic was introduced in the current transmission to reduce the loss.The fundamental harmonic approximation method was used to deduce the voltage gain,draw the gain curve,analyze the influence of resonance parameters on the voltage gain.The appropriate parameters were designed according to the de-mand.Variable frequency control was used to make the converter operate in different modes by regulating the input voltage to achieve stable voltage output.A 300 W experimental prototype was built with 55-220 V input and 30 V output.The experimental results show effectiveness of the converter topology and the proposed control strategy.
关键词
模态切换/三次谐波/宽增益/宽输入/基波近似法/开关损耗
Key words
mode switching/third harmonic/wide gain/wide input/fundamental harmonic approxima-tion/switch loss
维普
万方数据