Patent ID: 7199538
Filing Date: 2007-04-03
Classification: B62D,H02P

Abstract:
1. A motor driving system for an electric motor having a plurality of phase windings, said motor driving system comprising: a power source having a DC power source voltage (Vp); a pulse width modulating circuit which provides driving pulse signals for driving said phase windings, each of said driving pulse signals having pulses whose pulse width is modulated to have a prescribed duty ratio (Rd); an inverter having first switch elements respectively disposed between said phase windings and said power source and second switch elements respectively disposed between said phase windings and a ground, said flint and second switch elements being controlled according to the driving signals of said pulse width modulating circuit; a voltage calculating circuit for calculating level, of input voltage (Vi) to be respectively applied between said power source and said phase windings of said electric motor; a reference current calculating circuit for calculating reference values of current of said inverter from levels of the voltage applied between said power source and said phase windings of said electric motor, resistances disposed between said power source and said phase windings of said electric motor and the prescribed duty ratio; a current detecting circuit for detecting actual values of current of said inverter; and means for judging abnormality of phase current if one of the actual value of current of said inverter is a preset value different from corresponding one of the reference values.