A power supply unit operation is switched depending on a load requirement. Namely, when the load requirement is smaller than a predetermined value, operation of a fuel cell system is stopped and electric power is obtained from a secondary battery during an intermittent operation mode. Alternatively,...http://www.google.com.tw/patents/US7575825?utm_source=gb-gplus-share專利 US7575825 - Power supply system and control method of the same
