General arbitrary injection approach for synchronous machines

Abstract

In this paper, an approach is presented to calculate the rotor position of an permanent magnet synchronous machine from arbitrary current ripples. It makes no difference if the current ripple is generated by an injection or only by the pulse width modulation (PWM). For low speeds, where the current ripple of the PWM is not sufficient, the PWM pulses are shifted in order to increase the current ripple. In the medium and high speed region, this modification of the PWM is not required. Together with a standard field oriented control structure, this verified by experimental results.