A method of power regulation applied to the high frequency inverter for the IH home appliances

This paper describes a power regulation concept; CFPDM (Commercial Frequency Pulse Density Modulation) of the high frequency inverter for induction heating home appliances. CFPDM is a new type of PDM and it is easy to put CFPDM into practical use for any circuit topologies without any additional switches and passive components. Conventional PDM (Pulse Density Modulation) enables the high frequency inverter to control the output power over a broad range and to realize high power conversion efficiency at the same time. However, the resonant frequency of non-smoothing filter is close to the duty frequency of PDM, which may cause other harmonic current problems. In CFPDM, the duty frequency is set to lower than the line frequency unlike PLL. Therefore CFPDM surpass the advantages of PDM and also avoids generating harmonic current. This paper shows the sample of CFPDM controller and the operation principle by using simulated results. A prototype soft switching SEPP high frequency inverter controlled by CFPDM has been tested. Some experimental results of it are shown finally.