Analysis of the passive transient damping branch for suppressing the current spike and oscillation

To achieve higher output PWM frequency with limited switching frequency of devices, a topology named parallel frequency-multiplication is employed in this paper, which, however, leads to more serious current spike and oscillation in the turn-on transient because of the parallel of devices. Aiming at this issue, the theoretical analysis of transient process is presented to explain how the current spike and oscillation occur, and on this basis a passive transient damping method is proposed. By use of the different equivalent frequency band between steady and transient states, the damping effect only acts in switching transient process, so that the current spike and oscillation can be suppressed significantly but without additional steady losses. Moreover, the turn-on losses of power devices can be reduced remarkably as well. The experimental results show good agreement with the simulation, and both of them verify the validity of this method.