Eliminating scheme of zero-sequence currents in open-end winding induction motor drive with a single DC power supply

Open-end winding induction motor can be powered by double inverters at both ends. Comparing with conventional single-ended inverter induction motor drive, this new configuration produces some advantages, such as high error tolerance capability, high flexibility, and low DC voltage rating, and so on. Under single DC power supply however, the zero-sequence currents may be produced by the common mode voltage and circulate through the DC bus. The resulted additional loss not only degrades the operation efficiency and loading capacity, but also accelerates aging of the drive system. Non-ideality of inverter itself and the zero-sequence electromotive force in motor are the two main sources contributing to the zero-sequence currents. To eliminate the currents in the open-end winding induction motor, a space-vector PWM scheme with the capability of zero-sequence voltage control is proposed in this paper, and by active control to the zero-sequence voltage, elimination of the zero-sequence currents is achieved. Moreover, with the proposed PWM scheme, the total common-mode voltage with respect to the ground is reduced to a great extent, and the bearing and leakage currents are also feasible to be suppressed. On the test rig built in laboratory, the zero-sequence current eliminating scheme is tested and its validity and effectiveness are confirmed.