Patent ID: 7541758

Claim:
A metal-oxide semiconductor (MOS) rectifying device that is connected between a 3-phase alternating current (AC) generator and a direct current (DC) power source, the DC power source being charged by electric power supplied from said 3-phase AC generator, comprising: a bridge circuit, connected between said 3-phase AC generator and said DC power source, having 3-phase upper- and lower-arms, each of the upper- and lower-arms comprising a plurality of metal-oxide semiconductor field-effect transistors (MOSFETs); a first comparator that compares a first phase voltage of the 3-phase AC generator with a positive electrode potential of said DC power source; a lower-arm driver that, based on an output of said first comparator, starts the drive of a MOSFET of the lower-arm associated with a phase voltage before the first phase voltage; a second comparator that compares the first phase voltage of the 3-phase AC generator with a negative electrode potential of said DC power source; and an upper-arm driver that, based on an output of said second comparator, starts the drive of a MOSFET of the upper-arm associated with a phase voltage before the first phase voltage; and an error detector that detects an output voltage error of said 3-phase AC generator based on the output of said first and second comparators, wherein said lower-arm driver and said upper-arm driver turn off all of said plurality of MOSFETs based on an output of said error detector.