LAUSR

This article proposes a high step-up quasi-resonant converter that minimizes switching loss over a wide range of input voltages. By employing a bidirectional switch and corresponding switching modulation, the proposed converter achieves the main switch with almost zero voltage, and therefore incurs very little switching loss at all active switches. Moreover, no instantaneous reactive current flows through the circuit under wide variations of input voltages and loads. The duty cycle of primary-side switches is fixed to 0.5; then, the input and clamp capacitor voltages become identical, and thereby the following resonant capacitor voltages remain in balance. As a consequence, the proposed converter becomes compact and achieves high boost-ratio and high efficiency over a wide range of input voltages. The operating principle of the converter is presented along with its design procedure. 400-W/380-V prototype of the proposed converter has been implemented and tested at 40–60 V to verify its effectiveness.