| Abstract |
This paper describes a simplified analytical approach to compute iron losses of switched reluctance machines (SRM). The method is based on the combination between Lavers method and analytical calculations of stator and rotor pole flux linkage. The advantages of this method is that no SRM static flux characteristic is needed. It allows to assess qualitatively iron loss generated by the harmonics and also to study the influence of each parameter (current, advanced angle, tooth, ...). The first part of this work describes the analytical model of the stator and rotor pole flux densities, then these quantities are compared with those ones obtained using the finite elements method for a 8/6 SRM. A non linear extrapolation is used with the least squares method for the sinusoidal static iron losses characteristic to exploit the Lavers method. Then the influence of the current climbing on SRM iron loss is discussed. Both The influence of current commutations and regulation on these losses are verified experimentally. It is shown that these two parameters generate a lot of supplementary iron losses usually not considered in the previous theoretical models of iron loss prediction. The theoretical and the experimental results obtained for a 8/6, 2kW, SRM show that the commutation and the current regulation generate a local extreme in the stator pole flux waveforms. The last waveforms are obtained thanks to an auxiliary coil which has been wound around the machine stator pole. The local extreme generate supplementary iron losses reported to that estimated by the proposed procedure. |
