A general space vector PWM control algorithm for multilevel inverters

To solve the problem of computational complexity in multilevel inverters due to the large number of space vectors and redundant switching states, a simple and general space vector PWM algorithm is proposed. Based on this algorithm, the location of the reference voltage vector can be easily determined and the calculation of dwell times becomes very simple. More importantly, the proposed algorithm is general and can be directly applied to the cascaded H-bridge inverter of any voltage levels. In addition, a new switching sequence, large-small alternation (LSA), is proposed for the minimization of total harmonic distortion. To verify the algorithms, a 7-level cascaded H-bridge inverter drive system was constructed and experimental results are provided.