Performance of Adaptive MTPA Torque Per Amp Control at Multiple Operating Points for Induction Motor Drives

Maximum Torque Per Amp (MTPA) control offers highly efficient operation in induction motor drives since it achieves desired torque with minimal stator current. However, it was shown that the rotor resistance variation degraded performance of MTPA control significantly, thus leading to its failure to satisfy maximum torque per amp condition. To overcome the degradation caused by rotor resistance variation, adaptive MTPA control was proposed to take rotor resistance variation into consideration to achieve a desired torque with minimum stator current. In this work, performance of adaptive MTPA control strategy is investigated at multiple operating points. Experimental study shows that (i) accurate achievement of the desired torque (tracking performance), and (ii) consistent satisfaction of minimum stator current for the desired torque (maximum torque per amp condition) at multiple operating points, as rotor temperature increases.