Charging multiple batteries using the boost-flyback converter

A boost-flyback converter was investigated for its ability to charge separate battery stacks from a low-voltage high-current renewable energy source. A low voltage (12V) battery was connected in the boost configuration, and a high voltage (330V) battery stack was connected in the flyback configuration. This converter works extremely well for this application because it gives charging priority to the low voltage battery and dumps the reserve energy to the high voltage stack. As the low-voltage battery approaches full charge, more power is adaptively directed to the high-voltage stack, until finally the charging of the low voltage battery stops. A two-secondary flyback is also capable of this adaptive charging, but the boost-flyback does it with much higher conversion efficiency, and with a simpler (less expensive) transformer design.