Integrated Four-leg Inverter Structure For PMSM Drives with Open-phase Fault-tolerance and Internal Boost Operation
Résumé
An innovative four-leg inverter structure is proposed for three-phase permanent magnet synchronous machine (PMSM) drives in electric vehicles, which integrates the open-phase fault-tolerance and a boost function in the absence of a real boost stage. In this structure, the DC-source is connected between the neutral point of the motor and the fourth leg. The zero-sequence path of the whole structure can be simultaneously used in fault-tolerant and boost operations. To guarantee the stable torque output in post-fault conditions, the q-axis current should be maintained while the d-axis and 0-axis currents are reshaped by injecting different harmonic components. To track the post-fault current trajectories, a differential flatness-based controller is further proposed. Finally, experiments are carried out on a 1.2 kW PMSM to verify the effectiveness.