A novel over-modulation strategy for dual three-phase induction motor drive system

In this article, a novel strategy for dual three-phase converter operating in the over-modulation region is proposed. The strategy enables the magnitude of inverter output voltage a linear output with modulation index varying in both fundamental and harmonic components. In the proposed algorithm, the functional relationship between modulation index and the fundamental or harmonic voltage magnitude can be described by equations. It is a single-mode over-modulation strategy avoiding storing massive correlation data between modulation index and hold angle, which indicates the proposed algorithm is suitable for digital implementation. Furthermore, this strategy extends the range of operation of the power converter from linear-modulation range to 12-step operation with a smooth and linear transition characteristic, while stator harmonic current is suppressed based on a vector decomposition technique.