On-Vehicle Charging Generator and Rectifier Unit Thereof

In a rectifier unit having a MOSFET, there is provided a stable MOSFET rectifying operation which is not influenced by a power generation condition from a start of an engine. An output VS obtained by adding phase voltages VU, VV, and VW and a power generation voltage VBR are compared by COM1. During a period of VBR>VS, a timing signal VT having a cycle of an electrical angle of 120 degrees is obtained. In synchronism with rising of logical products AND1 and AND2 based on a comparison result VH-ON of a phase voltage VU and a power generation voltage VB and a comparison result VL-ON of a phase voltage VU and a GND potential, flip-flops FF1 and FF2 are operated. Then, a gate signal VHGD of an upper-stream side MOSFET and a gate signal VLGD of a lower-stream side MOSFET are outputted to execute a MOSFET rectifying operation.