A PEBB-based direct-link drive for open-ended AC machines

A PEBB-based direct-link converter arrangement for the control of an open-ended three-phase machine is analyzed in this paper. The converter arrangement requires only 18 unidirectional switches as compared to 36 in the original two matrix converter based topology [1]. In this arrangement, a 6-switch converter is connected to the grid followed by two inverters that are connected to the stator windings of an open-end machine. The two inverters operate in phase opposition and they are controlled such that the common-mode voltage across each machine phase is zero. Also, the common-mode voltage switching at the machine terminals is eliminated. The input phase currents have 120-degree-conduction and thus have low order harmonics with unity displacement-power-factor (DPF). A low input current THD scheme is proposed for applications where multiple electric drives are connected to the grid.