This paper proposes the modified Space vector PWM for the modified topology of high efficient threephase voltage source inverter (HE-VSI3), which consists of traditional six switches voltage source inverter and three bidirectional free-wheeling switches for creating the ac decoupling circuit. This topology has the advantages such as the ability to improve the efficiency based on the principle of decoupling, the ability of applying to the conventional VSI scheme, the simplicity of the control algorithm and can widely applied to many applications. The HE-VSI3 topology and modified space vector PWM method are simulated by using Matlab/Simulink software and implemented in the experimental prototype. The high efficiency is obtained very promising in the proposed scheme with modified SVPWM.