Abstract: In a battery charger, the rectifier includes rectifying elements provided for respective three phases. The rectifier supplies, for the respective phases, currents for rectifying three-phase AC voltages so as to charge a battery. A voltage detector detects whether or not the battery is charged. Switching units are provided for the respective rectifying elements, and rectify the AC voltages to charge the battery in the off-state. Switch controllers output gate signals in accordance with a timing of zero-cross detection upon receiving a detection signal indicating that all the gate signals for turning on and off the respective switching units for the respective phases are supplied in the order of the phases.

Abstract: Provided is a battery charging technique by which high efficiency of the battery charging can be always controlled no matter how the power consumption of the battery is changed. In a battery charger, a charging control circuit holds a charge/non-charge state of a battery during an arbitrary period of time in order to prevent the unbalance of phase voltages due to occurrence of transition between the charge/non-charge states during a short period of time and the reduction of the efficiency of the battery charging. Further, zero-crossing erroneous detection in a phase voltage of the output of a three-phase alternating-current generator due to noises is prevented.

Abstract: There is provided a battery charging technique by which various battery charging control can be achieved even when power consumption of a battery is small. In a battery charger, in order not to turn OFF a power switch even when an ACG starting detection circuit recognizes that an output of a generator is not generated in a state in which the power consumption of the battery is small and the voltage of the battery is not dropping, a voltage of the battery in addition to phase terminal signals of a three-phase alternating-current generator is inputted to the ACG starting detection circuit, and the ACG starting detection circuit controls not to turn OFF the power switch when the output of the three-phase alternating-current generator is generated or when the voltage of the battery is equal to or higher than a predetermined voltage.

Abstract: In a battery charger, the rectifier includes rectifying elements provided for respective three phases. The rectifier supplies, for the respective phases, currents for rectifying three-phase AC voltages so as to charge a battery. A voltage detector detects whether or not the battery is charged. Switching units are provided for the respective rectifying elements, and rectify the AC voltages to charge the battery in the off-state. Switch controllers output gate signals in accordance with a timing of zero-cross detection upon receiving a detection signal indicating that all the gate signals for turning on and off the respective switching units for the respective phases are supplied in the order of the phases.