A controller estimates a motor position. The controller includes a driver and an injector. The driver generates a fundamental control signal. The injector generates a position carrier voltage that superimposed on the fundamental control signal. The injector alters the magnitude of the carrier voltage signal in response to the corresponding amplitude of the fundamental control signal. In a disclosed example, the injector increases the carrier voltage signal magnitude as the fundamental control current signal approaches a zero crossing. The injector then gradually decreases the carrier voltage signal magnitude as the fundamental control current signal magnitude increases from zero.