On the analysis and reduction of the cogging torque of a claw pole transverse flux permanent magnet machine

The transverse flux permanent magnet machine (TFPM) is currently given an increasing attention, especially in electric and hybrid propulsion applications. Although significant improvements have been carried out on the earlier topologies, much work is still required before the TFPM can be regarded as a mature concept. Of particular interest is the cogging torque reduction which is a vital requirement in propulsion applications, as far as passenger comfort is concerned. The present paper deals with, in a first step, a three-dimensional (3D) finite element analysis (FEA)-based investigation of the cogging torque of a claw pole TFPM. Then, an approach to the cogging torque reduction based on skewing is proposed. This is done considering a single-phase TFPM concept. Then, the study is extended to the three-phase claw pole TFPM, considering different combinations of the axially-arranged phases. Copyright (c) 2005 John Wiley & Sons, Ltd.