Abstract: In order to cut the cost of servocontrol system of permanent-magnet synchronous motor, the paper used three low-resolution Hall sensors as position detecting device to estimate high-resolution rotor position information. The sensors reduced error of traditional low-resolution control technology at start-up and low-speed stage by using current compensation to estimate acceleration. The simulation results demonstrate that the method effectively improves stability of the motor at the low-speed stage, decreases estimation error of rotor position and gains favorable control performance in all-speed range.