混合式LLC电路谐振与同步整流数字式控制

Hybrid LLC Circuit Resonant and Synchronous Rectifier Digital Control

针对LLC电路混合式控制的特点,对频率控制和移相控制进行了数字控制的分析与建模。根据混合式LLC电路整流电流总处于断续状态的特点,分析得出输出电压与同步整流驱动占空比呈单峰值的关系,并以一种无需传感器的方法实现电路的同步整流控制,应用最优梯度滞环比较搜索法,能快速准确的搜索到同步整流最优驱动点。最后为减小谐振与同步整流间的控制干扰,利用数字式控制能储存谐振控制频率和相位的优点,对同步整流控制进行解耦,很好地提升了系统的动态性能。以一个输出20A/3.3V实验样机验证论文控制策略的正确性。

According to the characteristics of the hybrid LLC control circuit, frequency control and phase shift control of digital control was analyzed and modeled. Based on the characteristic, that the hybrid LLC circuit rectifier current is always on-off state, and the conclusion that the output voltage is single peak with the synchronous rectifier drive duty ratio, the synchronous rectifier control could be realized by a method without sensors. The control strategy could fast and accurately search the optimal point, by combination of hysteresis comparison with optimal gradient. Finally, in order to reduce the interference of harmonic and synchronous rectifier control, using the advantages of digital control can store frequency and phase of resonant control, decouple the control of synchronous rectifier control and improve greatly the dynamic performance of the system. The result verifies the control strategy by a 20 A/3.3 V output experiment prototype.