General Theory of Space Vector Modulation for Five-Phase Inverters

Multiphase motor drives are a very promising technology, especially for medium and high power ranges. As known, a multiphase motor drive cannot be analyzed using the space vector representation in a single d-q plane, but it is necessary to introduce multiple d-q planes. So far a general space vector modulation for multiphase inverters is not available due to the inherent difficulty of synthesizing more than one independent space vector simultaneously in different d-q planes. In this paper the problem of the space vector modulation of five-phase inverters is completely solved extending the theory of space vector modulation used for traditional three-phase voltage source inverters and introducing the concept of reciprocal vector. This approach leads to the definition of a very flexible modulation strategy that allows the full exploitation of the dc input voltage and the simultaneous modulation of voltage space vectors in different d-q planes. The validity of the proposed modulation theory is confirmed by experimental tests.