Abstract:

Proposed in this paper is a novel fast three-dimension space-vector pulse-width modulation （3D-SVPWM） algorithm for controlling the four-leg voltage source inverter. In this algorithm, the tetrahedron and action duration of the vector are directly determined by using three-phase reference voltages with simple calculation, thus remedying the shortcomings of complex calculation and large time cost of the conventional algorithm with coordinate transformation. The relationships between the proposed algorithm and three other modulation methods, including the time-domain control equation solution, the sinusoidal pulse-width modulation and the 2D-SVPWM of four-leg inverter, are analyzed, with an uniform action duration model of vector being also found. Moreover, the voltage utilization ratio of the inverter with 3D-SVPWM is analyzed, and the simulated results of the four-leg inverter with the four above-mentioned methods are compared. It is found that the proposed algorithm is correct and effective, and that the four above-mentioned methods are equivalent.

Key words: four-leg inverter, 3D space-vector pulse-width modulation, sinusoidal pulse-width modulation, fast al-gorithm