Nonlinear Optimal Control for 2.5-kW LLC Converts With Pulse Loads

Abstract

In the case of pulse load, the power supply is constantly switched from no-load to full-load, which would cause the output voltage to fluctuate. In order to reduce the voltage fluctuation and improve the dynamic performance, a nonlinear control method is proposed in this paper. When the voltage change is detected, the control strategy is changed to switch between burst control and PFM control. The proposed control strategy is verified on a 2.5kW LLC prototype. The experimental results demonstrated that the output voltage drops, overshoots and settling time are reduced over the SOTC control method. It shows that the control strategy has a good effect in the pulse load application.