Research On A Novel Hybrid DC/DC Converter With Four Switches

With the development of Power Electronics, the technology of Switching Mode Power Supply (SMPS) is gradually being perfect. The trend of SMPS towards high power efficiency high power density low electro-magnetic interference perfect electric performance small and portable performance. In the interest of the demand , soft-switching is proposed. In the medium and high power SMPS, phase shifting controlled ZVS PWM full-bridge converter is favour topology. But in this converter, ZVS is difficult to be achieved for the lagging leg at light load. In order to achieve ZVS for the leading leg and the lagging leg, there are usually two measures to be taken: connecting saturable inductor in series with transformer primary side; adding a auxiliary resonant circuit. But the former measure will deteriorate reduction of the effective duty cycle, and the latter will increase complexity of the converter.This paper proposes a novel converter, which bases on a principle of Phase-shifting (PS) Zero-Voltage-Switching (ZVS) PWM Full-Bridge (FB) DC / DC converter and soft-switching Half-Bridge, aim at avoiding faults of the PS ZVS PWM FB converter. The proposed converter, which features high efficiency, high power-density and lower EMI, can achieve Zero-Voltage-Switching for all the switches from no-load to full load and better dynamic characteristics.For explaining the principle of this proposed converter, all the switching modes in a switching period is analyzed in detail. The analysis results show that ZVS is achieved for each switch under full-load-range. Therefore, the proposed converter can operate at higher frequency, reduce the output filter's volume, improve power-density and produce lower EMI. The proposed converter has lower conduction loss than the conventional PS ZVS PWM FB converter during clamping free-wheeling interval. The filter requirement is reduced due to near-ideal filter waveforms and so that the proposed converter can achieve better dynamic characteristics. Finally,the simulation results simulated in Saber and the experimental results have verified the all the characteristics above.