Mingze Wang

In the open-winding permanent magnet synchronous motor (OW-PMSM) system fed by dual-inverter with common DC bus, suitable control strategy should be adopted to suppress the torque ripple generated by the third harmonic flux and 0-axis current. However, the mathematical model will change when the motor is under open-phase fault so that the coordinate transformations and control strategy should be redesigned accordingly in order to suppress the torque ripple. In this paper, the post-fault OW-PMSM system is remodeled considering the third harmonic flux. Based on the post-fault model, new coordinate transformations are designed to obtain a concise torque and decoupling voltage expressions for the simple and accurate control of torque. Moreover, the torque ripple is suppressed by modifying the current reference. In addition, a simple decoupling modulation is designed to directly obtain the switching signals for the dual-inverter. Experimental results confirm the effectiveness of the proposed fault-tolerant control strategy.

For open winding permanent magnet synchronous motor (OW-PMSM) system with two isolated DC voltage sources, the distribution of voltage vectors (VVs) is different under different DC-link voltage ratios. In this Letter, a universal lookup table (LUT) based direct torque control (DTC) strategy is proposed for OW-PMSM drives under different conditions of DC-link voltage ratio. The distribution criterion of VVs under various DC-link voltage ratios is analyzed and the VVs are assigned to different regions by designing a generalized region division scheme. A universal LUT is established to realize the selection of required VV in DTC strategy. Experiment results validate the effectiveness of the proposed universal LUT based DTC strategy for OW-PMSM system with different voltage ratios.

This paper proposes a dual two-vector based model predictive flux control (DTV-MPFC) strategy for open winding permanent magnet synchronous motor (OW-PMSM) drives with two isolated voltage source inverters (VSIs). In MPFC strategy, the reference stator flux vector can be compensated to realize field weakening (FW) operation by controlling the value of the cost function. However, the accuracy of the cost function based FW strategy is limited when the tracking error of stator flux vector exists. In this paper, a DTV-MPFC strategy is proposed to synthesize the reference flux increment vector precisely and the FW operation boundary is kept within the linear modulation region to enhance the FW operation performance. Each inverter applies two vectors during the control period and the switching frequency of the VSIs is minimized with the proposed strategy. When the DC-link voltages of the VSIs are unequal, the number of candidate flux increment vectors and the distribution of the space vector plane are different. A generalized vector selection and duration calculation scheme is proposed to realize DTV-MPFC strategy in this case. Experimental studies are carried out to verify the validity and effectiveness of the proposed strategy.