Optimization of a Line-Start Motor for Centrifugal Loads within Premium Efficiency According to IEC Standard

Line-start motors are gaining more attention in recent years as they can achieve very high efficiency while retaining the ability to self-start when connected directly to the grid. However, motor design is not a trivial matter, particularly when a certain compromise has to be found between performance at steady-state and the ability to synchronise even with large inertial loads. In this study the design of a line-start motor for centrifugal loads is presented, with particular attention to the rotor geometry, adopting a multi-objective optimisation including finite element analysis. Thanks to a proper selection of the objective function, both efficiency at steady state and starting capability are included in the optimization process.