Design Considerations for PDM Ac/ac Converter Implementation

Pulse Density Modulation (PDM) control of rectifier - series resonant inverter sets makes it possible to design ac/ac converters with good performance. However, implementation issues must be addressed to draw full advantage of the structure, namely low losses, small size and low EMI noise. Indeed some problems with synchronization, frequency adaptation and transformer design emerge. In this paper, a control circuit is proposed to solve the synchronization and frequency adaptation problems, and an optimized transformer design procedure, which considers the PDM operation features, is defined. Experimental results of a 1,2kW@110kHz prototype are presented.