Four-Leg Converter for Reluctance Machine With DC-Biased Sinusoidal Winding Current

This paper proposes a novel four-leg converter topology and the corresponding SVPWM strategy for a reluctance machine with DC-biased sinusoidal winding current. Compared with the traditional open-winding inverter topology, the number of the power devices and gate driver required for the four-leg converter topology are reduced by one-third, and the power loss is reduced. With the proposed four-leg converter, the cost of the motor drive is reduced and the power density is improved. The vector control and modulation models of the proposed four-leg converter are presented to control the winding current with both AC and DC components. With the proposed four-leg SVPWM strategy, the four-leg converter can achieve the same DC voltage utilization as an open-winding inverter. In addition to the ability to generate αβ -axis voltages, as same with conventional SVPWM, the proposed SVPWM can also generate γ -axis voltages without generating additional zero-sequence alternating voltages on the stator windings. The validity of the proposed converter and the corresponding modulation strategy has been demonstrated by simulation and experiment. The power loss and performance of the four-leg converter are compared with the traditional converter. Contrasting experiments show that the proposed topology can reduce power loss by about 15% at rated operation and achieve the same performance as open-winding inverters.