In order to solve the problems of slow starting speed of IF control and weak starting torque ability, the high frequency pulse voltage injection method was used to complete zero low speed starting of the motor, and combined with the effective flux method in the middle and high speed area, the position sensorless composite control strategy was formed in the full speed range. In order to achieve smooth switching between the two control methods, a hysteresis switching strategy combined with a state machine based on the speed transition region was proposed. The entire speed range was divided by the proposed strategy into the zero-low speed area, the transition area, and the medium-high speed area. When the motor entered the transition area from the medium-high speed area, the high frequency pulse voltage injection method was started in advance to stabilize the position estimation process and prepare for the switch. In order to reduce the impact of the injected high frequency voltage on the position estimation process of the effective flux method, the input and exit of the high frequency pulse voltage injection method were realized by soft switching in the speed transition zone. In order to solve the coupling problem when two position estimation methods work simultaneously in the speed transition region, a double synchronous rotating coordinate system was set up to realize the decoupled control of rotor position estimation. The effectiveness of the proposed method was verified on a three-phase permanent magnet synchronous motor.