Proposing a Multimode Switching Control Method for a Half-Bridge Converter to Improve Its Efficiency Over the Entire Load Variations.

The aim of this paper is to propose a novel switching control method to improve the efficiency of the basic half-bridge converter for the whole range of the load current. Using multimode control for this purpose, instead of modifying the structure of the converter, is proposed for the first time. Efficiency improvement is achieved by using a digital controller to select and change the control mode to the most efficient one, for each of the load sub-ranges. Control modes are prominent ones, including asymmetric, duty phase shift, pulsewidth modulation, and burst control, and are selected in turn, while the load current varies in its entire range from the full down to the no-load. The three transition points between control modes, being specific values of the load current, are analytically determined based on comparing the half-bridge converter power losses for different control modes. The digital controller compares the load current with the transition points and puts the converter in the control mode with the highest efficiency. The accuracy of the analytically determined transition points and the efficiency improvement of the proposed control method over the previous ones are investigated and approved by the experimental results. [ABSTRACT FROM AUTHOR]