Variable speed ac drives are nowadays the work horse of industry. To obtain variable voltage and frequency supply, inverters are the most common choice. Various pulse width modulation (PWM) techniques have been developed for three phase voltage source inverters in the last decade. Space vector PWM technique is the most popular choice due to their easier digital implementation and better dc bus utilization when compared to the most commonly used carrier based PWM scheme. In discontinuous PWM mode one of the leg of inverter is tied to either positive or negative rail of DC bus. This paper is devoted to the development of Space vector PWM strategies in discontinuous mode for three-phase VSIs. Discontinuous Space vector PWM offer the advantage of lower switching losses which is important especially in high switching frequency applications. The paper analyses various existing discontinuous PWM techniques based on harmonic performance of the output phase voltages. The harmonic performance indices chosen are total harmonic distortion, weighted total harmonic distortion and harmonic distortion factor. The performance is evaluated based on low-order harmonic content in the output phase voltages. Further few novel Space vector PWM method in discontinuous mode is proposed and analyzed. Performance comparison of the existing techniques and proposed schemes are presented. The analysis is done using Matlab simulation.