A three-level five-phase space-vector modulation algorithm based on the decomposition method

Open-end winding variable speed drives with dual-inverter supply have been extensively investigated for various applications, including series hybrid power-trains and propulsion motors. The topology is simple to realise while offering a higher number of switching states without the need for capacitor balancing algorithms, when compared to standard multi-level converters. The overwhelming majority of work is however restricted to the three-phase electric machinery. One of the reasons for this is that inclusion of a multi-phase machine leads to exponential increase in the number of possible switching states and so the design of a suitable space vector modulator (SVM) represents a considerable challenge. This paper considers a relatively simple SVM algorithm based on the decomposition of the three-level space vector decagon into a number of two-level decagons. The proposed modulation technique has the advantage of being relatively simple to implement. The method activates up to fifteen phase voltage levels and produces output voltages with minimum low order harmonic content. Despite the simplicity of the method, the THD of the output voltages is improved, compared to the previously proposed methods. The developed scheme is verified via simulation and the harmonic performance is analysed.