An Improved Single Switch Wide Range ZVS Forward Converter Controlled With Variable Magnetizing Inductance
Hesamodin Allahyari, Mohammad Ali Latifzadeh, Hamid Bahrami, Ehsan Adib, Hadi Faezi
Abstract
In this paper, a new self-driven synchronous rectification (SR) single switch forward (SSF) converter controlled with variable magnetizing inductance providing the wide range zero-voltage switching (ZVS) condition is proposed. The leakage inductance of the transformer functions as a virtual inductance in this converter, which transfers power to the secondary side. Remarkably, the suggested converter performs in discontinuous conduction mode (DCM). An auxiliary capacitor is utilized along with leakage and magnetizing inductances to obtain the ZVS condition for the main switch and reset the transformer core. Unlike typical forward converters, this converter does not consist of any freewheel diode, output inductor, reset diode, or extra reset winding, making the proposed converter topology simple and low-cost. In contrast to typical ZVS forward converters, this converter eliminates any auxiliary switch to reset the magnetic core and offers soft switching. The suggested converter operates by fixed pulse width modulation (PWM), fixed duty cycle, and fixed frequency. To regulate the output voltage versus the output power and input voltage variations, the magnetizing inductance is varied by the controller. To accomplish the variable magnetizing inductance, a direct current (DC) bias winding is employed. The suggested converter is theoretically investigated thoroughly, and the theoretical findings are validated with experimental results by building an implemented prototype.