An improved space vector PWM method for a three-level inverter with reduced THD

Among the multilevel inverters, the three-phase threelevel neutral point clamped (NPC) inverter is widely used for high power, medium voltage applications due to its superior performance compared to a two-level inverter. Proper control of such inverters is realized using modulation techniques, such as space vector pulse width modulation (SVPWM) which is having many advantages with reference to its implementation and harmonic reduction. This paper refers to a three phase three-level neutral point clamped inverter using space vector modulation technique. The algorithm to find the duty cycles of the inverter switches are based on the two-level inverter on-time calculations. An improved switching sequence is proposed in this paper to reduce the Total Harmonic Distortion (THD) in the line voltage and line current. The three-level inverter is simulated using the simplified algorithm and modified switching sequence. Harmonics analysis is carried out and compared with conventional SVPWM method.