A driver unit for an interior permanent magnet motor (IPM) is presented. The driver unit includes sensor electronics configured to sense a phase voltage corresponding to one or more phase terminals of the IPM motor to generate a corresponding phase voltage signal. The driver unit further includes a controller electrically coupled to the sensor electronics and configured to extract one or more triplen harmonics of an order of a ninth harmonic and higher than the ninth harmonic of a fundamental frequency of the phase voltage signal corresponding to the one or more phase terminals. The controller is further configured to determine an angular position of a rotor of the IPM motor based on the extracted one or more triplen harmonics. Related motor assembly and method for controlling the IPM motor are also presented.