A Saturation-Adaptive Field-Weakening Strategy for Wide-Speed-Range SynRM Drives With Complex-Vector Flux-Linkage Control

The performance of synchronous reluctance motors (SynRMs) degrades substantially when magnetic saturation is neglected in the control strategy. This omission leads to a distorted field-weakening (FW) trajectory, which deteriorates both steady-state and dynamic performance at high speeds. To address this issue, this article proposes a saturation-adaptive FW strategy integrated with flux-linkage control. An accurate flux-linkage model incorporating saturation effects is first established. Using this model, the FW strategy employs polar-coordinate lookup tables for precise maximum-torque-per-ampere and maximum-torque-per-voltage tracking across a wide speed range. Furthermore, a complex-vector flux-linkage controller is designed directly in the discrete domain. This controller achieves dynamic decoupling and provides inherent compensation for the time delay. Experimental results on a 7.5 kW SynRM drive validate the effectiveness of the integrated scheme. The proposed scheme extends the stable load range by more than 30 percentage points of the rated torque at 0.2 per-unit (p.u.) speed. It also reduces the acceleration time from standstill to 3 p.u. speed by 9.4%. Therefore, the proposed scheme offers a high-performance solution for industrial drives requiring wide-speed-range operation.