Research On Active-clamping ZVS Interleaved Forward Three-level Converter

With increasingly high demand in energy efficiency today, developed a green, high efficiency, high power level switching power becomes particularly important. Using multi-level technology not only reduce the harmonic pollution, but also reduce the voltage stress of the switching device, thus multi-level technology is more suitable for high-voltage, high power density applications. This paper will study for the shortcoming of three-level DC-DC converter, propose appropriate measures for improvement, in order to improve the overall performance of the converter.This paper combined forward converter and three-level inverter, not only isolate the electrical input and output, but also reduce voltage stress on the switch; On this basis, introduced by interleaved structure, reducing the input and output voltage ripple; introduced the active clamp means to ensure the completion of an effective magnetic transformer reset; use on the load side of the filter inductor with a center tap, softened diode turn-off process. Using the chopper control strategy and within a half cycle of the circuit is divided into 10 working modes. Determined by theoretical calculations and model parameters of each device to ensure the device reliably circuit requirements; the combination results in chaos analysis to ensure that the inverter can be stably run, and will not appear very different phenomenon and design expectations. By Pspice software simulation results verify the feasibility of the converter.Based on TMS320F2812 control system for the control of the DSP core, completed the six-way PWM signal converter required software protection and PI closed-loop control; and on this basis the corresponding drive circuit design, protection and the protection of the detection circuit implementation of the circuit. Combined software and hardware to ensure the converter is capable of safe, reliable operation.To further verify the realization of the measures to improve the converter, designed a prototype system 48V/4A,80 k Hz’s. As it can be seen from the results of experimental prototype system debugging, significantly reducing harmonic content of the output; inverter switching ZVS tube has an ideal environment; switch tube voltage stress decreased; the input and output voltage ripple has been significantly improved; filter inductor with a center-tapped softened diode during turn-off, reducing the voltage transformer primary and secondary overshoot and shock. According to the results of the experimental prototype verified this design feasibility and correctness of the proposed converter.