基于占空比主动调节的钳位开关电容型DC/DC解耦控制策略

Decoupled control strategy based on duty-ratio active regulation forclamping switched capacitors-based DC/DC application

钳位开关电容型DC/DC(Clamping Switched Capacitors-based DC/DC,CSC)是构建具有直流故障自清除能力直流变压器的有效模块。由于传统控制策略下的CSC中直流电压与电容电压存在着耦合效应,直流电压的变化将直接引起电容电压与交流环节电压幅值的变化,使得CSC在两端直流电压不匹配时可能发生软开关丢失、电流应力增大、功率损耗增加等运行性能下降的现象。鉴于此,为改善CSC在直流电压不匹配时的开关及效率性能,提出了一种基于可变占空比的CSC电容电压解耦控制策略。该策略可以在CSC的整个运行范围内保证交流电压幅值的自动匹配,对于改善CSC的整体运行性能具有明显效果。基于试验样机,验证了所提控制策略的正确性与有效性。

The clamping switch capacitor-based DC/DC(CSC)is an effective module to construct the DC transformer with the capability of DC faults clearing.However,the voltage amplitude of capacitor and AC-link will be influenced directly by the change of DC voltages in the traditional control of CSC because of the coupling effect of DC voltage and capacitor voltage,thus the loss of soft-switching,the increase of current stress and power loss may occur when the DC voltages are unmatched.In view of this issue,a capacitor voltage decoupled control strategy based on the variable duty-ratio is presented for CSC to improve the switching and efficiency performance when the DC voltage is unmatched.The proposed control strategy can guarantee the amplitude of AC voltages is matched in the full-operating-range of CSC automatically,so the efficiency of CSC can be enhanced obviously.The correctness and effectiveness of the proposed control strategy are validated by the prototype.