Space-Vector PWM Technique for Five-Phase Open-End Winding PMSM Drive Operating in the Overmodulation Region

The five-phase open-end winding inverter topology has a low-impedance zero-sequence current path when a single dc supply is used. As a result of this, any source of common-mode voltage in the circuit can lead to an uncontrolled low-frequency zero-sequence current. This is an issue for permanent magnet machine systems as they can possess zero-sequence components in the back electromotive force, which will couple with the generated zero-sequence current to produce undesired torque pulsations. One possible solution for reducing these torque pulsations is to use a zero-sequence proportional-integral current controller to actively suppress the zero-sequence current to zero. This requires a modulation technique, which can independently control the common-mode voltage. However, there is currently no reported space-vector modulation technique, which can independently control common-mode voltage while operating in the overmodulation region. Consequently, this paper develops a novel space-vector modulation technique for the five-phase open-end winding topology to address this issue. Experimental open-loop results prove that the proposed technique can accurately control common-mode voltage at any operating point with the tradeoff of producing increased switching band harmonics. Experimental closed-loop results prove that this modulation technique can be combined with a zero-sequence proportional-integral controller to actively suppress low-frequency zero-sequence current to zero in the overmodulation region.