具有输出耦合电感的高压增益双管正激组合变换器

为了克服双管正激变换器电压增益低、不适合应用于高输出电压场合的弱点,本文提出了一种具有输出耦合电感的高电压增益双管正激组合变换器。该组合变换器既具有双管正激变换器高可靠性的优点,同时电压增益是双管正激变换器的4倍。因此,在相同输入和输出电压条件下,该组合变换器的高频变压器副边输出续流二极管电压应力,为双管正激变换器对应二极管电压应力的1/4,从而在高输出电压应用场合,副边输出续流二极管可以采用低压快恢复二极管,极大地改善了续流二极管的反向恢复问题,提高了变换器的可靠性。

Combined Two-Transistor Forward Converter with Output Coupled-Inductor and High Voltage Gain

To overcome drawbacks of the low duty cycle and the low voltage gain of two-transistor forward converter(TTFC) and only in low output voltage,a novel combined two-transistor forward converter(CTTFC) with a output filter coupled-inductor is proposed.The converter is connected in parallel on the input side for the higher input current and in series by the coupled-inductor on the output side for the higher output voltage.The CTTFC has high reliability and the valid duty cycle.Its voltage gain is four times than that of the TTFC.So under the condition of the same input and output voltages,the voltage stress of secondary side freewheeling diodes of CTTFC is 1/4 of the corresponding diodes of the TTFC.As a result,the CTTFC is suited to the high output voltage application,and its secondary side freewheeling diodes can be replaced by low voltage fast recovery ones,thus improving the reverse-recovery problem of diodes and enhancing the reliability of the converter.