In order to improve the start performance of electrical vehicles, a new method used to track the initial rotor position is proposed. ....is method is based on the high-frequency (HF) voltage model and the software phase locked loop (PLL).. After HF voltage signal is injected into motor, the initial rotor position signal is modulated by high-frequency carrier wave, and then a PLL is adopted to track the initial rotor position after the HF current signal was treated with heterodyning. The HF injection method and PLL are introduced in the paper, then the experiments on the rotor position self-sensing during start process are carried out. The performance of this method is demonstrated by a real-time implementation using a digital signal processor (DSP) chip on a permanentmagnet synchronous motor with sinusoidal flux distribution. Theoretic analysis and experiments verify the validity and feasibility of this approach.