The voltage of 36-V battery (10) is dropped by the DCDC converter
(12) to charge the 12-V battery (14). The switching ON/OFF of the
DCDC converter (12) is feed forward controlled by the controlling
portion (20). This can cope with the voltage change at the 36-V battery
(10). The output voltage of the DCDC converter (12) is feed
back controlled by a differential amplifier (16) and PID (18) and
feed back by the controlling portion (20).
