A new space vector PWM techniques control for nine-leg inverters: analysis and FPGA implementation

Nine-leg voltage source inverters (VSIs) are highly effective topologies for high-power industrial applications. In this paper, a novel space vector with pulse-width modulation (SVPWM) approach for a nine-leg VSI fed three-star induction machines (TSIMs) is proposed. In fact, for nine-leg VSI fed TSIM, large stator harmonic currents are observed in the case of a 30 degrees electrical shift between stator stars. The main objective of this paper is to minimize the circulation of these harmonics on (x-y) and (z-w) planes by developing a new SVPWM strategy for the nine-leg VSI. The effectiveness of the proposed strategy in terms of reducing the stator harmonic currents and electromagnetic torque ripple on the topology is, firstly, verified by computer simulations at different levels of the modulation index. The obtained results show that a compromise between the proposed technique and the proper choice of the modulation index provides high performance of the topology. On the other hand, an experimental test on a laboratory prototype of the nine-leg VSI fed TSIM shifted by 30 degrees is carried out using a Virtex 5 LX50T FPGA. The experimental results prove the accuracy of the numerical results and therefore the efficacy of the proposed technique.