The influence of the inverter switching frequency on rotor losses in high-speed permanent magnet machines: An experimental study

Harmonic content of the output voltage of pulse width modulated voltage source inverters (PWM VSI) is determined by the switching frequency. On the other hand, rotor losses in high-speed permanent magnet (PM) machines are caused, among other factors, by harmonics in stator currents. These harmonics are determined by the harmonics in the inverter output voltage, and therefore dependent on the switching frequency. In high-speed PM machines, due to the high fundamental frequency, harmonics in the stator currents caused by PWM are located at very high frequencies. Measurement of rotor losses caused by these harmonics in a structure with a conductive retaining sleeve on the rotor which is prone to eddy currents might be very challenging. This paper investigates issues related to this measurement and presents a measurement method which results are compared with results from a 2D analytical model that takes into account eddy currents in the rotor.

[1]  Thomas A. Lipo,et al.  Pulse Width Modulation for Power Converters: Principles and Practice , 2003 .

[2]  K. Yamazaki,et al.  Loss Investigation of Interior Permanent-Magnet Motors Considering Carrier Harmonics and Magnet Eddy Currents , 2009, IEEE Transactions on Industry Applications.

[3]  J. Pyrhonen,et al.  Analysis of rotor eddy current losses in slotless high-speed permanent magnet machines , 2014, 2014 16th European Conference on Power Electronics and Applications.

[4]  E. Lomonova,et al.  Modeling the influence of commutation in voltage source inverters on rotor losses of permanent magnet machines , 2014, 2014 16th European Conference on Power Electronics and Applications.

[5]  Gang Chen,et al.  Overview of power loss measurement techniques in power electronics systems , 2002, Conference Record of the 2002 IEEE Industry Applications Conference. 37th IAS Annual Meeting (Cat. No.02CH37344).

[6]  Nigel Schofield,et al.  Improved analytical modelling of rotor eddy current loss in brushless machines equipped with surface-mounted permanent magnets , 2004 .

[7]  S. R. Holm,et al.  Analytical Modeling of a Permanent-Magnet Synchronous Machine in a Flywheel , 2007, IEEE Transactions on Magnetics.

[8]  E. Furlani.  Permanent Magnet and Electromechanical Devices: Materials, Analysis, and Applications , 2001 .

[9]  E. A. Lomonova,et al.  Comparative analysis of rotor losses in high-speed permanent magnet machines with different winding configurations considering the influence of the inverter PWM , 2015, 2015 Tenth International Conference on Ecological Vehicles and Renewable Energies (EVER).

[10]  Johannes J. H. Paulides,et al.  General Formulation of the Electromagnetic Field Distribution in Machines and Devices Using Fourier Analysis , 2010, IEEE Transactions on Magnetics.

[11]  Holmes,et al.  Pulse width modulation for power converters , 2003 .