Analysis of synchronous-reluctance machines for all-wheel-drive systems

  Geometry and characteristic diagram of SRM Copyright: © IEM

In this project, the use of synchronous reluctance machines (SynRM) as all-wheel drive modules in electrically driven vehicles is investigated. The investigations are divided into the rough design of the respective machine, the construction of the CAD geometry, the electromagnetic finite element analysis (FEA) and the post-processing to calculate the machine-specific maps. This procedure is performed for the three selected machine topologies, permanent magnet excited synchronous machine (PMSM), asynchronous machine (ASM) and synchronous-reluctance machine (SynRM), for a high speed and a high torque application.

The focus of the investigation is the comparison of the machines regarding their suitability as additional traction machine (all-wheel drive module). Besides the occasional traction operation, the no-load operation, which always occurs when the all-wheel module does not contribute to the traction and is dragged along, is to be examined. Here, the topologies show different suitability. The Cogging torque of the PMSM essentially leads to increased losses of the entire drive system, when the machine is only dragged along, while the topology-related, poor power factor of the SynRM is particularly noticeable in the field weakening area and requires over dimensioning of the power electronics. The aim is to determine the efficiency of the machines at the above-mentioned operating points and to derive from the overall efficiency a recommendation regarding the suitability of the respective topology as a traction machine for all-wheel drive modules.