Fixed angle control frequency tracking in series connected high-frequency inverter

For series connected inverter and using power MOSFETs as power switches, a new automatic tracking method for the inverter´s frequency using PLL and fixed angle control was introduced in this paper after analyzing the normal working state of the inverter. The experiment results verify that the tracking rate is quick and exact and the inverter is always working at a little-inductive state that makes the inverter work under the quasiresonance state, that is, the power factor is close to 1. Experiments also showed that the method could make the power MOSFETs work at a soft-switch state.