This paper proposes an inductance-based estimation method for sensorless interior permanent magnet synchronous machine drives. Rotor position estimation is based on magnetic saliency and employs high-frequency components of voltage and current excited by a multiphase space vector pulse width modulation pattern. Unique to this method is that not only the rotor position but also the inductance parameter values can be estimated instantaneously during a period of modulation. Since inductance is an essential parameter for magnet polarity identification and maximum torque per ampere control, this paper presents the principles and performance results of the proposed inductance estimation method. Experimental results confirm that the proposed method is reliable, real-time, accurate, and convenient.