A novel isolated DC DC converter with improved efficiency for fuel cell based DC power supply systems

For fuel cells based power supplies, necessity for operation for a wide input range presents a problem for realizing synchronous rectification for achieving higher converter efficiency. A novel design scheme that allows synchronous rectification with isolated interleaved active clamp converter is introduced in this paper. It involves a pre-regulating buck converter for part of the fuel cell output range. Interleaving helps achieve higher efficiency due to reduced rms current per phase; allows higher power transfer and reduces the input ripple current. Input current is accurately limited to protect fuel cell stacks from damage during overload. The converter PWM strategy is analyzed and verified experimentally on a 500 W prototype.