Series Load Resonant High Frequency Research Articles

A Novel Type of Series Load Resonant High Frequency Soft Switching Inverter with Phase Shift Control Scheme

The voltage source full bridge series load resonant high frequency soft switching inverter using pulse phaseshift modulation (PSM) strategy is proposed, which can operate ZVS in the left hand side bridge leg and ZCS in the right side bridge leg. This inverter using IGBTs employs two passive components and does not need any additional auxiliary circuit for the active power switch to achieve soft switching commutation, and it has wide soft switching operation region from full power to 3% light power. Furthermore, constant frequency power regulation that is required for induction-heating power applications is introduced on the basis of PSM. In this paper, steady state switching modes of the inverter treated here and its power regulation scheme by PSM are described under a soft switching scheme. Because the proposed inverter can operate at series resonant frequency of series resonant circuit under soft switching condition, it is easy to design the value of series resonant capacitor. The design methods of loss-less snubbing circuit components for soft switching are described to reduce switching losses effectively. The feasible experiment of the proposed inverter is implemented to demonstrate the power regulation performance of proposed high frequency inverter, high efficiency 97.6% at full power condition is obtained.

Quasi-series-resonant-type soft-switching phase shift modulated inverter

A prototype of a series-load resonant and quasi-resonant hybrid-type soft-switching high frequency inverter is proposed for induction heating applications, together with its operating principle. The bridge legs of the inverter treated here have the salient feature of a power regulation function under a constant switching frequency which is based on pulse phase shift modulation due to the current leading leg and the current lagging leg. Because quasi-resonant current flowing through each active power switch becomes a trapezoidal waveform or quasi-square waveform due to the quasi-series resonant operation, it is expected that the conduction loss increase by the peak current through each power semiconductor switching device in the full bridge arm be basically suppressed as compared with that of the conventional series load resonant high frequency inverter. The design procedure of circuit components to achieve a soft-switching of this high frequency inverter, the reduction effect of switch peak voltage stress and its power regulation performance are described and discussed in detail. The effectiveness of the 5 kW–21 kHz soft-switching pulse phase shift modulated high frequency inverter using the IGBT power modules is proved on the basis of the power regulation performance and power conversion efficiency.