A Novel Space Vector PWM Technique With Duty Cycle Optimization Through Zero Vectors for Dual Three-Phase PMSM

In this paper, a novel space vector pulse width modulation (SVPWM) technique with duty cycle optimization through zero vectors for dual three-phase (3-ph) permanent magnet synchronous machines (PMSMs) is proposed. Dual 3-ph PMSMs can be optimally controlled in vector space decomposition, which allows controls of the fundamental component and main low-frequency harmonics separately in two orthogonal subspaces, i.e., αβ and xy subspaces. However, the space voltage vector modulations of voltage references in two subspaces are not independent, because each voltage vector possesses its unique and fixed spatial location in two subspaces. Therefore, many SVPWM techniques intend to extend the modulation capability by designing the voltage vector selection principle, but the duty cycle saturation determines the limit of phase voltage regardless of the voltage vector selection principle. Therefore, a simple SVPWM technique with duty cycle optimization by adjusting dwell times of zero vectors is developed to offer a reasonable modulation capability with reduced switching frequency and no complex voltage vector selection principle. The linear modulation range is explained as well. Finally, the experimental results validate the performance of the proposed SVPWM technique through voltage injection and closed-loop current control.