Simulation studies of flyback DC/DC converter with active clamp circuit

To yield energy from the low-voltage power source such as a photovoltaic panel or a fuel cell it is necessary to connect it with step-up DC/DC converter. Among many step-up topologies there are two basic types of converters: ones with and ones without galvanic isolation. Although both types provide voltage gain thanks to the turns ratio of transformer or coupled inductor, electrical isolation in some applications is essential. This paper presents an isolated DC/DC flyback converter using an active clamp and dual series resonance circuits. The converter operates as an isolated voltage amplifier with a voltage gain B dependent on duty cycle D and input voltage V_in. Through the use of transistors with low drain to source resistance R_DS(on) conduction losses of main transistor switch can be reduced. The reverse recovery current of output rectifier can be omitted thanks to resonant tank consisted of transformer leakage inductance and voltage doubler capacitors. Active clamp circuit allows the energy transfer to the load in the two stages as in the forward converter. The 2-kW flyback converter simulation model was developed. Input voltage V_in varied from 12V to 48V and output voltage above 330V needed for 1-phase DC to AC conversion was achieved. Maximum converter efficiency was 92.3%.