PWM modulation for a three-level inverter with neutral-point balancing for a permanent magnet synchronous machine

A neutral point (NP) balancing modulation for a three-level inverter with cosφ > 0.9 is presented. In the low modulation range, standard space vector modulation (SVM) is applied using the redundancy of the small space vectors (SV) for the NP balancing. In the high modulation range, the switching sequence is adapted so that the neutral-point voltage can be also balanced. The proposed method is compared with the modulation concept of the virtual SV concept. Experimental validation of the modulation scheme is presented.