Influence of MTPA Trajectory Evaluation on Synchronous Machines Performance

Interior permanent magnet machines are characterized by high efficiency over a wide speed range. The optimal performance of these motors can be achieved by implementing the appropriate control strategies: Maximum Torque per Ampere (MTPA), Flux Weakening (FW) and Maximum Torque per Volt (MTPV). The optimal MTPA control trajectories can be found with different methods employing an inductance based model or a flux based model. In principle, the two methods are the equivalent, however, the different numerical method for the evaluation of the control trajectory can lead to slightly different results. Four motors are chosen for the analysis: an IPM machine, a pure reluctance machine, a SPM machine and a reluctance assisted machine. The results obtained from the two the models are compared with 2D-FEA simultion results.