In this thesis, to improve the performance of senorless control for interior permanent magnet synchronous machine (IPMSM), four topics containing online compensation of inverter voltage error, IPMSM parameters measurement, wide-speed range sensorless control and initial rotor polarity detection are studied in detail. For the online compensation of inverter voltage error, an adaptive sigmoidal function (S-function) model is firstly proposed to estimate and compensate the voltage distortion. For the IPMSM parameters measurement, an identification method of resistance and inductance is proposed, which only using VSI at standstill, and the effects of inverter voltage error and current measurement error are analyzed and compensated. For wide-speed-range sensorless control, this thesis combines the high-frequency injection (HFI) method and sliding mode observer (SMO) to accomplish the sensorless control in both low-speed range and high-speed range. Furthermore, a speed-dependent weight function is designed as a transition between these two methods. For initial rotor polarity detection, this thesis proposes a novel rotor polarity detection method based on torque-pulse injection. This method can also be applied to the IPMSM with low saturation effect, for which the conventional rotor polarity detection method is invalid. All the methods proposed in this thesis are validated by plenty of experiments.