Research On Main Circuit Topological Structure Of High Frequency High Power Inverter Based On MOSFET

At present, in studying and developing heavy capacities and parallel resonant inverter, it is expected to solve the problems of researching on simple structure and easy to start frequently series resonant inverter in the fields of domestic high frequency induction heating installation. Therefore, researching of the subject is to design and study a high frequency (more than 1 MHz) and high power topological structures of full solid-state induction heating power supply. Through analyzing and comparing several typical high frequency inverter circuits, an available high power topological structure is selected. All of these offer and plan good preparation of earlier stage for power source designing and device debugging, and reducing device cost and raising working efficiency.With a view to improving operating frequency, MOSFET' HF characteristic is discussed in detail. It is considered that HF loss is one of the key factors for influencing operating frequency of inverter. Therefore, under the circumstances, several requirements and measures are proposed for high-speed MOSFET driver circuit and reducing MOSFET HF loss. For raising and improving the output powers of inverter, method of multi-devices connected in parallel is utilized for increasing equipment capacity. Theprinciple and characteristics of balancing parallel MOSFETs in static and dynamic mode are analyzed detailed in this paper. For the limitations of traditional PWM hard switching circuit, a kind of zero of pair soft switching technology is introduced and the switching loss can be cut down by it and the reliability of inverter in case of high frequency can be improved also. ZVS soft switching resonant circuit is selected after analyzing and comparing ZVS and ZCS soft switching resonant circuit. Grounding on above theory, the ZVS resonant of soft switch full-bridges circuit, and class-E amplifier, and push-pull class-E amplifier are analyzed respectively in theory. Push-pull class-E amplifier is available by comparing results of simulation and low power experiment. The experiment verified the validity that push-pull class-E amplifier is more suitable for high frequency high-power inverter. It can achieve relatively high power in high frequency. Experiment result proved, relative to complicated structure and high request for laying wiring of ZVS series resonant full-bridges, push-pull class-E amplifier is expected more suited for high frequency high-power output ability relatively, which is suitable for popularizing.