New Control Method, with the Aim of Optimizing the Efficiency of Half Bridge Converter under the load variations

In this paper, a new multi-mode control method is proposed to optimize the efficiency of the half bridge converter under the load variations. Efficiency optimization is performed by only changing the control mode and without adding elements to the main converter structure. The control method uses the prominent control modes including asymmetrical, duty phase shift, pulse width modulation (PWM) and burst control. For the first time, three transition points between control modes, being the specific values of the load current, are analytically calculated based on full bridge converter power losses. Transition points are used as the criteria for allocating the control mode and are functions of the half-bridge converter parameters. The proposed method continuously compares the load current with the transition points and puts the converter in the control mode with the highest efficiency. Thus, the half-bridge converter efficiency is optimized in terms of control modes and over the load variations. The accuracy of the analytically determined transition points and superiority of the proposed control method to the previous ones is determined by illustrating the performance of the converter.