Inductance calculations for PM machines with concentrated windings

The usage of three phase permanent magnet (PM) machines with concentrated coil fractional pitch double layer windings, proofs to be very cost-effective for range extenders in the automotive sector. However, the number of possible slot pole combinations for these machine types is countless. This paper presents an analytical method for calculating the inductance components of these electrical machine types. This method can be used for calculations of all possible slot pole combinations. It does so by first deriving the machine optimal winding configuration. The machine winding configuration is then used to set up an armature reaction flux model. From the armature reaction flux the different inductance components, including the self-inductance with its main and leakage component and the mutual-inductance component can be determined. The analytical model is used for the inductance calculations of two prototype generators for the Peec-Power range extender. The results are compared to FEM calculations. An accurate analytical model is the result.