无传感器混合式LLC电路同步整流数字控制策略

Digital synchronous rectification control of sensorless hybrid LLC circuit

详细分析了混合式LLC电路移相模式下的开关损耗,以损耗最小为依据确定了混合控制的最优转换点。根据混合式LLC电路整流电流为近似正弦断续的特点,提出一种与LLC谐振控制共享电压检测且无需额外传感器的同步整流控制策略。该策略采用最优梯度滞环比较算法,可较好实现混合式LLC电路同步整流的数字控制,具有良好的调节速度和精确度。以一个36~72 V输入、3.3V/20A输出的实验样机验证了所提理论的正确性和可行性。

The switching loss of hybrid LLC circuit in phase-shift mode is analyzed and the optimal converting point of hybrid control is determined according to the minimum loss. As the rectifying current of the LLC circuit is approximately sinusoidal and intermittent,a strategy of synchronous rectification control is proposed,which shares the voltage detection with the LLC resonant control and does not need additional sensors. It adopts the optimal gradient hysteresis comparison algorithm to realize the digital synchronous rectification control of LLC circuit,with better regulation speed and accuracy. An experiment with a prototype of 36 ~72 V input and 3.3 V/20 A output verifies the correctness and feasibility of the proposed theory.