According to the characteristics of nonlinear and coupling of the mathematical model of current PWM inverter in dq synchronous rotating coordinate, the doublering decoupling additional PI control strategy was designed. Firstly, the composition and principle of the system was analyzed, and then the mathematical model of PWM inverter and the double-ring decoupling additional PI control strategy were detailedly introduced. Finally system speed, voltage and current, active power, reactive power and power factor were simulated in the MATIAB/Simulink software. The results proved that the control strategy not only could achieve smooth and stepless speed regulation, but also could achieve the purpose of improving power factor, eliminating harmonic and saving energy.