The advantages such as better fault-tolerant capability, less space harmonic content, and requirement of power semiconductor devices with reduced voltage ratings etc., made the multi-phase induction machines drives (IMD) best desirable for the high power applications. However, as the number of phase increases, the improvement in the LMR of the multi-phase IMDs is not significant using the conventional SVPWM techniques provided in the literature. To address the above-mentioned limitation, 18-sided polygon (octadecagon) based voltage space vector generation for a nine-phase IMD is proposed in this article without compromising in the torque harmonic profile. Using the proposed octadecagonal voltage space vector generation technique, the LMR of nine-phase IMD is significantly improved by 26.03%, 24.28%, and 9.15% in comparison to the nine-phase sinusoidal pulse width modulation, nine-phase SVPWM and individual hexagonal SVPWM techniques, respectively. Efficacy of the proposed control technique is substantiated using the results obtained from ANSYS Maxwell simulation and experimentation on 5-hp nine-phase IMD prototype in the laboratory. © 2021 John Wiley & Sons Ltd.