高反向增益的双向LLC变换器变模式控制策略

Variable Mode Control Strategy of Bidirectional LLC Converter with High Reverse Gain

针对传统双向半桥LLC谐振变换器反向工作增益范围较窄的问题,提出了通过移相控制和变频控制相结合的变模式控制策略。反向输入电压较低时,采用移相控制提升电压增益;反向输入电压较高时,采用变频控制实现一次侧开关管零电压开通和二次侧整流二极管零电流关断,降低开关损耗。首先对升压模式进行了数学建模,推导了其增益公式,并通过MATLAB仿真验证该策略的科学性。该控制策略在不增加辅助元件的情况下,增大了LLC变换器的增益控制范围,提升了工作适应性。

To solve the problem of narrow reverse working gain range of traditional bidirectional half-bridge LLC resonant converter,a variable mode control strategy combining phase shift control and frequency conversion control is proposed.When the reverse input voltage is low,the maximum voltage gain is obtained by phase shift control.When the reverse input voltage is high,the frequency conversion control is adopted to realize the zero voltage on of the primary side switch and the zero current off of the secondary side rectifier diode,so as to reduce the switching loss.The boost mode is mathematically modeled,its gain formula is deduced,and the strategy is verified by MATLAB simulation.The control strategy increases the gain control range of LLC converter and improves the working adaptability without adding auxiliary components.