Research On ZVZCS Three-Level Converter With Passive Clamp Circuit

Environment and energy problems issues power electronics discipline for the efficient power generation, conversion and control requirements. In such a high-efficiency, high-performance power conversion request, soft-switching multi-level conversion technology has been attracting more and more attentions. Three-level converter has the advantage that the switch voltage stress is only half of the input voltage. Associated with soft-switching technology, it is very suitable for high input voltage, middle or large power applications. In view of the situation, for reducing switching loss, improving current trails of IGBT and improving the converter efficiency, a novel ZVZCS three-level DC-DC converter using passive clamp circuit is proposed. The operation principle of the converter is analyzed as well as parameter design and control characteristics.Based on the analysis of small-signal model of the Buck converter, the small-signal model of the ZVZCS three-level DC-DC converter is built according to operating characteristics and the resonant mechanism by using the method of PWM switch equivalent model. Transfer function and frequency characteristics of the system are analyzed. The design of compensator enhances the system with good dynamic and static performance.PSpice is used to simulate the operation of the three-level converter. By adjusting the parameters of simulation, the performance of circuit is optimized. The correctness of the proposed three-level converter is proved.To verify the feasibility of the design, combining DSP digital control, a 144 W, 60 kHz ZVZCS three-level experimental prototype is built. The power circuit, driving and protection circuit of the converter are designed. TMS320F2812 is used to constitute control circuit.Experiments of the prototype are carried out. From the experiment result, it can be indicated that the ZVZCS three-level converter using passive clamp circuit has wider soft-switching load range, lower voltage stress on switch, lower overshoot voltage on the rectifier diode and high efficiency. The performance requirements of the converter are achieved, and the correctness of the theoretical analysis is verified.