Dynamic response improvement in a buck type converter using capacitor current feed-forward control

The dynamic performance of dc-dc power electronic converters is mainly determined by the output filtering capacitor and inductor, control loop(s) compensator(s), and the voltage conversion ratio. Normally, a larger capacitance and/or a smaller inductance are not recommended because of the extra cost and size of the capacitor and/or the increment of the inductor current ripple. The capacitor current feedforward method has gained popularity due its fast dynamic response, simpler structure, and less sensing losses. In applications where a large voltage conversion ratio is needed, dynamic response for a load step-down scenario is worse than that of a load step-up condition. In order to alleviate this situation, a buck derived dc-dc converter is chosen. By combing the capacitor current feed-forward control and the buck derived converter topology, a novel control scheme is proposed in this paper. Simulation results containing the voltage overshoot and settling time are presented. The proposed approach is a high performance, simple structure, and low cost/volume strategy for load step-down dynamic improvements.