| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electric power steering system in which estimation accuracy of an electric angle is improved when sensorless control is performed. <P>SOLUTION: A state determination unit 115 determines to be in a steering retaining state when the absolute value of differential values eu', ev', ew' of induced voltage even in only one phase is not more than a determination value A close to zero. When it is determined to be in the steering retaining state, a wire-wound resistance calculation unit 116 sets the arithmetical value of induced voltages eu, ev, ew generated in an electric motor 20 to zero, and calculates wire-wound resistances Ru, Rv, Rw from motor terminal voltages Vu, Vv, Vw and motor currents Iu, Iv, Iw. A wire-wound resistance correction unit 117 updates the wire-wound resistances Ru, Rv, Rw in an arithmetic expression stored in each phase induced voltage calculation unit 111 to the value calculated by the wire resistance calculation unit 116. <P>COPYRIGHT: (C)2011,JPO&INPIT |
