Comparison of end effect in series and parallel hybrid permanent magnet variable flux memory machines

Hybrid permanent magnet (PM) variable flux memory (VFM) machines employ both the high coercive force PM, i.e. the constant PM (CPM), and the low coercive force PM, i.e. the variable PM (VPM), with which the PM magnetization state can be flexibly regulated to match various operation requirements. These two kinds of PMs can be magnetically connected with either parallel or series configuration so that different characteristics can be obtained. Based on two-dimensional (2-D) and three-dimensional (3-D) finite element (FE) analyses, the end effects of a pair of VFM machines with parallel and series connections, respectively, are investigated to identify their different features. The prototype machines are manufactured and tested to validate the predictions.