Space Vector based Hybrid PWM Schemes for Three-level Inverters to reduce Current Ripple

This paper proposes three space-vector-based hybrid switching schemes for a three phase three-level neutral point clamped inverter fed load. The three new hybrid PWM schemes are compared with centered space vector PWM (CSVPWM), bus clamping PWM (BCPWM), advanced bus clamping PWM (ABCPWM) and existing five zone hybrid PWM schemes in terms of line current ripple. It is found that the proposed seven-zone hybrid scheme reduces ripple in line current by about 39 % when compared with CSVPWM scheme at full modulation index and results in least distortion throughout linear modulation range.