| The phase-shifted full-bridge (PS FB) pulse-width-modulated (PWM) DC-DC converters with zero-voltage switching (ZVS) or zero-current switching (ZCS) have many advantages, such as low switching stresses, low switching losses and high frequency. So they are widely used in high input voltage and middle-to-high power DC-DC converters.The operating principle and circuit characteristics of the PS FB ZVS PWM DC-DC converter with blocking capacitor are analyzed in this paper, and the effect of blocking capacitor on the converter's performance is especially discussed. According to the different values of blocking capacitor, the several related processes, such as the free-wheeling period of the resonant inductor current, the switching transition of lagging leg and the current transfer process of diode rectifiers, can be divided into two modes. The critical value of the blocking capacitor is deduced based on the critical condition. The duty ratio loss in different modes are analyzed, and it is found that the duty ratio loss is much less in the case of C_b |
PDF Full Text Request