Design of resonant converter for high power factor operation and optimum losses in magnetic components

This work presents a systematic design procedure of resonant converter for its operation in high input line power factor. Selection of quality factor of the resonant tank circuit influences instantaneous gain and power factor of the converter. The design calculations are done for AC to DC modified series-parallel resonant converter (MSPRC) delivering a peak power of 2P_o (P_o is output power), by choosing quality factor Q at the peak of AC line cycle for minimum AC input voltage. For high power factor operation the value of Q at peak of AC input should be chosen such that the instantaneous available gain of the converter is greater than the required gain. Design of magnetic components under cost and loss constraints is outlined. The optimal number and the diameter of the strands to minimize loss in magnetic components are given for particular design example. The sub-optimal stranding is also considered to arrive at best cost-loss compromised designs. A MATLAB program is used to arrive at cost-loss compromised design. To validate the design procedures simulation results of a typical MSPRC are presented. Finally results of an experimental prototype built in the laboratory are given to substantiate the outlined design procedure.