Balancing Peak-torque and Drive-cycle Efficiency with Magnet Dimensioning of Permanent Magnet Synchronous Machines

There is an increasing trend in reducing rare-earth materials due to environmental and cost concerns. It affects design and manufacturing of Permanent Magnet Synchronous Machines (PMSM). Changes in parameters such as size and shape of the magnets will affect requirements as operating efficiency and maximum torque. In this paper, the design of a 250 kW PMSM for a commercial heavy-duty vehicle application is considered in order to evaluate effects of magnets thickness variation on performance and driving cycle efficiency. With this aim, an electromagnetic model is built using Finite Element Method (FEM) and efficiency map computations are carried out to investigate the effects of the magnet variation. System simulations are then implemented in MATLAB/PLECS to evaluate the driving cycle efficiency. Simulation results shown that the reduction of magnet thickness leads to significantly improved operating efficiency with reduction of maximum torque.