This paper presents an investigation on the influences of number of phases of Transverse Flux Permanent Magnet (TFPM) machines on the characteristics of developed electromagnetic torque. Electromagnetic torque is expressed in terms of the Fourier series of phase currents and internal voltages. After some algebraic and trigonometric calculations, a general equation is obtained that establishes a relationship between the electromagnetic torque ripples, number of phases and harmonic contents of both internal voltages and phase currents. This result is significant when it is required to design a few specific number of identical single-phase TFPM machines which finally they will be assembled such that to build a multi-phase machine with a minimum torque ripple. The design parameters of a case study Claw Pole TFPM machine are introduced with some details and a few FE based simulation results are given as the validations of the analytical approach of the present paper. The simulation results show clearly the impact of each harmonic of the internal voltages and phase currents on the torque ripple for various numbers of phases leading the designer to find out which number of single-phase machine combinations is the optimum one regarding the torque ripple.

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This paper presents the influence of several structural factors and parameters involved in the design of Claw Pole Transvers Flux Permanent Magnet Machines (TFPMs) on their internal voltage. Knowing the influence of each factor is very important for an effective process of design and optimization for these machines. In this paper by using the complete design algorithm of Claw Pole TFPM, only one parameter is changed at a time and its influence on the internal voltage is analyzed. Output torque is also studied, because the internal voltage has effect on both the average and the ripple of output torque. The most important factors and parameters which are considered are: 1) number of poles; 2) length of air gap; 3) ratio of magnet arc to flux concentrator arc in each pole of rotor; 4) shape of pole shoe of stator and 5) area of rotor pole covered by stator pole. Due to geometrical complexities of TFPMs, analytical methods fail to describe the behavior of these machines. For this reason, in this paper finite element analysis is used both in the design and analysis of TFPMs.