A high resolution pulse width modulation technique using concentric multilevel dodecagonal voltage space vector structures

In this paper, a new PWM technique for induction motor drives involving six concentric dodecagonal space vector structures is proposed. Apart from increasing the linear modulation range compared to a hexagonal space vector structure, the proposed configuration helps in total elimination of 5^th and 7^th order harmonics from the phase voltage throughout the modulation range. Thus, it is possible to operate the inverters at a reduced switching frequency without compromising on the quality of output sinusoidal voltage being fabricated. The space vector structure is realized by feeding an open-end induction motor drive from two three-level inverters having isolated asymmetric DC link voltages. Simulation and experimental results presented in this paper show the applicability and usefulness of the concept for high power drives.