Eddy current losses of high-speed permanent magnet synchronous motor
Permanent address of the item is
Suurnopeuksisen kestomagneettitahtimoottorin pyörrevirtahäviöt
In this thesis, an Ingersoll-Rand made high-speed permanent magnet synchronous motor is simulated by using the finite element method. The interest for Ingersoll-Rand in this work is to study how to use the open source software Elmer for electric machine simulations. This work is written at FS Dynamics’ office in Tampere. FS Dynamics is a co-partner in this thesis and their motivation is to learn more about electromagnetic simulations. The use of numerical simulations for the electric machines are increasing since these simulations give a good estimation of the machine properties. Simulations are especially effective in electric machine design since they reduce the number of prototypes required and thus the manufacturing costs of the machine. In addition, the variables at some points of the geometry cannot be measured in real life but the numerical method will give an estimation of the calculated variable at every point in the geometry. In electric machines, the interesting variables include the magnetic flux density and current density. This thesis explains how to create a workflow for simulating electric machines using Elmer as a solver. This workflow consists of creating the geometry model by SpaceClaim, mesh by Salome and post-processing is done by using Paraview and Python scripts. The motor is simulated in four different operation points. These simulations consist of nominal load and no-load operation of the motor. At both of these operation points, the stator windings are supplied with sinusoidal voltage or pulse width modulated voltage. The eddy current losses and copper losses are studied at these different simulation cases and compared to each other. From the results, it is clearly seen that the pulse width modulated voltage increases these losses in both operation points. The nominal load total losses are higher compared to the no-load total losses since the currents are lower without the load. The eddy current losses decrease when changing the motor operation from the nominal load to no-load with sinusoidal supply. However, with the pulse width modulated voltage the eddy current losses increase when changing the operation point. In addition, the start-up transients in the simulations can be reduced by the following three methods. The motor is started by the ramped sinusoidal signal. Electric conductivity is added after the motor has reached steady-state operation. At last, the sinusoidal voltage is changed to pulse width modulated voltage during one fundamental period. These methods were found working rather well in this thesis.