A method of controlling an IPM machine having a salient rotor. Stator terminal signals are measured and rotated to obtain synchronous reference frame current signals. A rotor position is estimated based on an impedance generated using the rotor and included in the current signals. The estimated rotor position is used to control the machine. An alternator-starter system in which this method is used can provide high cranking torque and generation power over a wide speed range while providing operational efficiency.