Patent ID: 8159180

Claim:
A battery charging device that is connected between an alternating current generator and a battery, and converts alternating current power output from the alternating current generator into direct current power and supplies the direct current power to the battery, the device comprising: a rectifier circuit that has a bridge configuration formed by switching elements, and that performs advance angle/delay angle control by either advancing or delaying energization timing to the switching elements relative to a phase of an alternating current output voltage of the alternating current generator; a power generation amount calculation circuit that detects an output voltage and an output current of the alternating current generator, and calculates a power generation amount of the alternating current generator; an advance angle/delay angle calculation circuit that generates a differential voltage between a voltage of the battery and a predetermined target voltage, and determines an advance angle/delay angle amount of the energization timing to the switching elements based on the differential voltage; an advance angle/delay angle control circuit that performs advance angle/delay angle control of the switching elements using the advance angle/delay angle amount determined by the advance angle/delay angle calculation circuit, and that, when a delay angle amount exceeds a delay angle limit value in case where delay angle control is performed, performs delay angle control of the switching elements using the delay angle limit value; and a delay angle limit value setting circuit configured to dynamically store the delay angle amount and the power generation amount, and dynamically compare a previous delay angle amount and a previous power generation amount with a current delay angle amount and a current power generation amount, and when the current delay angle amount is larger than the previous delay angle amount and the previous power generation amount is larger than the current power generation amount, set the previous delay angle amount as the delay angle limit value.