Abstract: A battery charger includes a plurality of rectifier, a plurality of switches respectively for the plurality of rectifier elements, a zero-crossing detector, a switch controller, and a detection reference changer. The plurality of rectifier elements rectify AC voltages of three phases output from a power generator. The plurality of rectifier elements, in an off-state, causes the plurality of rectifier elements to rectify the AC voltages to charge a battery. The plurality of rectifier elements, in an on-state, causes the AC voltages to be short-circuited to a negative side of the battery. The zero-crossing detector detects zero-crossings of the AC voltages. The switch controller outputs, based on the zero crossings, a gate signal for turning on and off the plurality of switches. The detection reference changer changes a reference for the zero-crossing detector to detect the zero crossings.

Abstract: A battery charger includes a plurality of rectifier, a plurality of switches respectively for the plurality of rectifier elements, a zero-crossing detector, a switch controller, and a detection reference changer. The plurality of rectifier elements rectify AC voltages of three phases output from a power generator. The plurality of rectifier elements, in an off-state, causes the plurality of rectifier elements to rectify the AC voltages to charge a battery. The plurality of rectifier elements, in an on-state, causes the AC voltages to be short-circuited to a negative side of the battery. The zero-crossing detector detects zero-crossings of the AC voltages. The switch controller outputs, based on the zero crossings, a gate signal for turning on and off the plurality of switches. The detection reference changer changes a reference for the zero-crossing detector to detect the zero crossings.