Analysis of the Influence of NdFeB Permanent Magnet’s Type and Volume on the Characteristics of a PM Claw-pole Alternator

This paper proposes an analytical method to calculate the magnetic flux in the air gap of a claw-pole alternator, created by a NdFeB permanent magnet in the rotor. The proposed method can also be used to calculate the dimensions and the volume of a permanent magnet that will create a desired voltage in the machine. The possibility to obtain a certain value of the machine voltage with lower volume of rare earth material will lead to a decrease in the cost of the final product. The need for such a method is grounded on the complex geometry of this type of electrical machines, which would require a time consuming 3D modelling with FEM analysis software. Knowing the air-gap magnetic flux of the machine permits the right choice of permanent magnet type and volume, which facilitates the designing phase of the alternator. The influence of the permanent magnet's cross section and length on the magnetic flux in the air-gap of the alternator is analyzed. A comparison between the electromotive forces created by a permanent magnets with different grades is made and presented.