Zero-sequence current suppression for open-end winding induction motor drive with resonant controller

Open-end winding topology with a common DC source has path for zero-sequence current. Zero-sequence current needs to be suppressed because it does not contribute to the drive torque but has harmful effects such as loss and torque ripple. Both inverter and motor have sources of the zero-sequence component. The zero-sequence source on the inverter side is the voltage error due to dead time in switching. The zero-sequence source on the motor side is the zero-sequence component of the back EMF which consists of the third harmonic. In this paper, the two zero-sequence sources are investigated both theoretically and experimentally for an open-end winding induction motor drive system, and a method to suppress the zero-sequence current suppression is proposed. The voltage error is compensated by feedforward to the reference voltage. The zero-sequence component of the back EMF is compensated by a proportional and resonant controller because its frequency is known while its amplitude and phase offset are unknown.