Cell voltage balancing of a series-connected multiphase BLDC motor drive

Brushless DC operation with a trapezoidal waveform of permanent magnet machines provides a simple, robust and cost effective method to drive the motor. In this paper, the proven technology is applied to a motor drive system with series-connected multiphase windings and converter cells. The proposed topology provides a modular approach and enables MOSFET, which is more cost-effective and efficient, to replace the IGBT which is typically used in 3-phase motor drives. Cell voltage balancing in this topology is also studied and the result shows that the cell voltages have a potential to self balance. A 2 kW prototype has been built and tested to validate the conclusion.