Modeling and simulation of sensorless control of four-leg inverter PMSM drives in the case of a single-phase open circuit fault

This paper introduces a new method to track the saliency of a permanent magnet synchronous motor (PMSM) motor fed by a 4-leg inverter in the case of a single-phase open circuit fault through measuring the dynamic current response of the motor line currents due to the insulated-gate bipolar transistor (IGBT) switching actions. In the case of a single-phase open circuit fault, a fault-tolerant control strategy that includes taking appropriate actions to control the 2 remaining healthy currents results in minor system performance degradation. The new strategy introduced in this paper includes software modifications only to the saliency tracking algorithm used in healthy mode in order to make it applicable to the reconfigured converter in the presence of a fault. The new method uses only the fundamental pulse width modulation (PWM) waveform (i.e. there is no modification to the operation of the 4-leg inverter), similar to the fundamental PWM method proposed for a 3-leg inverter. Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by fault-tolerant 4-phase inverter over a wide range of speeds under the case of a single-phase open circuit fault.