| Induction heating power supply is a kind of equipment that heats the work piece by eddy current and is applied widely in industry because of its many virtues. The emergence of fast power semiconductor switching devices such as MOSFETS has made it possible to implement high-frequency inverters for induction heating. This paper analyzes the high-frequency (MHZ) multi-devices parallel inverter, and presents some useful results of simulation and experiment.Firstly, Series resonant inverter is selected by comparing two inverter circuits. In this part, the high-frequency series inverter with resonant pole capacitor is introduced mainly. The current-exchanging processes of the inverter in different working modes are analyzed, how to reduce the switching loss is discussed, and the calculating methods of snubber capacitor C, factor angle switching frequency and pulse width PW are given in optimum switching process. And results of simulation and experiment verify the validity of theoretic analysis.For the inverter control circuit, the simulation model of 74HC4046 is established. Two pulse signals can be obtained by forming dead time, which are used to drive the switching devices. Through the combination of inverter circuit and PLL circuit, the process of frequency-tracking is described, and the experimental waves can be reflected perfectly. This provides someexperience for the designing and debugging of electrical source.In addition, it is analyzed and simulated in detail that parallel MOSFETs maybe make currents unbalanced because of the unequal parameters of component under MHZ conditions. Lots of experiments are preformed and some available measures are taken to make the currents balanced.At last, the simulation model of PLL is used in inverter circuit, the dynamical performance of the whole system is simulated, and the switching loss is analyzed under different conditions. The method of evaluating the stress ability of power MOSFET is given, which is benefit for the system designing.
|
PDF Full Text Request