A self-driven synchronous rectification wide-range ZVS single-switch forward converter controlled using the variable inductance

A new single switch ZVS forward converter with a wide soft-switching range is proposed here. Compared to the conventional forward converter, the proposed converter uses fewer components and operates under ZVS soft switching. A capacitor, along with both the leakage and magnetizing inductances, provides ZVS soft switching and transformer core reset. To regulate the output voltage against the input voltage and the load variations, an inductor is added to the converter. The inductance of the additional inductor varies with the direct current (DC) of the DC bias winding to regulate the output voltage. Therefore, the duty cycle and the switching frequency are constant in the proposed converter. With the constant duty cycle and the constant switching frequency, the wide ZVS soft switching is achieved. The proposed converter is completely analysed theoretically. The finite element analysis is used to design the additional inductor. By designing an experimental prototype, the theoretical analysis is justified using the experimental results.