For full-speed position sensorless control of surface-mounted permanent magnet synchronous motor (SPMSM), this paper presents a hybrid position sensorless control scheme based on combination of I/F control and nonlinear flux observer. In low-speed region, the I/F control method is utilized for the stable startup and reliable operation. In medium-speed and high-speed region, a nonlinear flux observer and a phase locked loop (PLL) is introduced for position estimation. In response to the common switching oscillation problem in hybrid control methods, this paper proposes a current fusion switching method based on PI control; And combine the linear extended state observer (LESO) with the current fusion switching method to further form compound switching method. In addition, simulations and experiments are designed to verify the switching performance of the two methods. The results show that both proposed methods can achieve smooth switching of control strategies, and compound switching method has better performance during the transition process.