基于移相补偿的全桥LLC谐振变换器交错并联技术

An Interleaved Full-Bridge LLC Resonant Converter with Phase Shift Compensation

LLC谐振变换器具有高频化、高效率和高功率密度的优点,近年来已被广泛应用。但由于电路本身的特点,输出电流纹波较大,需要多个输出滤波电容并联,这给系统的体积和应用场所带来了一定的限制。为解决这个问题,可采用交错并联技术,但是谐振元件参数存在的偏差,使得LLC谐振变换器并联时输出电流无法均分。为此提出一种适用于全桥LLC谐振变换器交错并联的均流控制方案,输出电压由脉冲频率调制(PFM)控制,因谐振元件参数偏差引起的负载不均流,由移相调制(PSM)补偿,并根据移相角的大小,动态调节两路LLC谐振变换器之间的交错角,进一步减小输出电流的纹波。在理论分析的基础上,设计并制作一台实验样机,实验结果验证了提出方法的可行性和有效性。

LLC resonant converter with the advantages of high frequency, high efficiency and high power density, has been widely used in recent years. However, due to the characteristics of the circuit, the output current ripple is larger, requiring multiple output filter capacitors in parallel, which limits the volume and application of the system. In order to solve this problem, interleaving parallel technology can be used, but the parameter deviations of resonant circuits make the current balance hard for LLC resonant converter. Therefore, a current-sharing control strategy is proposed applying the interleaved full-bridge LLC resonant converter. In this method, the output voltage is controlled by the pulse frequency modulation（PFM）, the current unbalance caused by the parameters deviation is compensated by the phase shift modulation（PSM）, and the interleaved angle between two LLC resonant converters is dynamically adjusted according to the phase shift angle to further reduce the output current ripple. On the basis of theoretical analysis, an experimental prototype was designed and built, and the results verified the proposed method.