Comparison Between Different Modelling Methods to Study the Dynamical Behaviour of Line Start Permanent Magnet Synchronous Motors

To reach energy efficiency goals the demand to high efficient motors, e.g. Permanent Magnet Motors, is increasing. It is hard to start permanent magnet synchronous motors direct on line. Including power electronics is expensive and power consuming. Therefore, a rotor cage offers a solution in systems without need of control. Although the problem of starting can be solved using the rotor cage, these machines still fail to synchronize in some situations. These failures can have a negative influence on the performance of the machine, due to heating. To investigate the performance of the motor in many situations, simulation techniques have to be used. The choice among these techniques depends on the requirements of the design. Three common techniques can be found: Finite Element Analysis (FEA), Magnetic Equivalent Circuits (MEC) and the 2-phase modelling in a rotor reference frame (dq). techniques. In this paper not only their benefits and drawbacks, but also their complementarity is discussed. The discussion is illustrated with case examples.