Vector control has improved the performance and energy efficiency in SPIM drives. However, high current and torque pulsations are produced by winding asymmetry of SPIM. This paper proposes a decoupling scheme to reduce the current and torque pulsations and improve the performance of vector control. A stator current observer is used to estimate the coupling signals, which are compensated by control law. This method is an alternative to improve the performance of single-phase induction motor used in hermetic refrigeration systems. The thermal efficiency of refrigeration system can be improved by the variable speed operation and the advantages of robustness and low-cost of single-phase induction motor can be maintained.