An investigation of bifilar wound three-phase induction motor drives operating with only low side switches

In this paper, the stator and inverter losses that result from operating an induction motor with bifilar windings are investigated and compared with a conventional delta connection. The bifilar wound connection offers the benefit of requiring only low side power devices which simplifies the design of the inverter. The magnitude of diode recovery and shoot through currents are also limited and current protection for the power device can be achieved with simple circuits as level shifting of control signals is eliminated. However, AC currents at the switching frequency are introduced into the motor which leads to additional losses. Losses occur as a result of conditions specific to the bifilar operation as well as those present in other motor connections. The loss mechanisms are discussed and possible causes given, as well as the implications of the bifilar connection on copper losses and device utilisation.