| 摘要 |
A control device ( 30 ) calculates an upper limit value of a duty ratio (DR_Ulim) according to a voltage (Vm) from a voltage sensor ( 13 ) and a threshold voltage (OVb) when an overvoltage is determined to have been applied to a battery (B), and determines a duty ratio (DR) for providing switching control to NPN transistors (Q 1 , Q 2 ) in a range lower than the calculated upper limit value of the duty ratio (DR_Ulim). The control device ( 30 ) uses the determined duty ratio (DR) to provide switching control to the NPN transistors (Q 1 , Q 2 ). Then, an up-convener ( 12 ) converts a direct current voltage (Vb) from the battery (B) into the output voltage (Vm) such that an overvoltage is not applied to the battery (B). |
