Analytical modelling for surface-inset permanent-magnet machines accounting demagnetization effects

This papers proposes a modelling technique for the demagnetization effect in surface-inset permanent-magnet synchronous machines. The geometry of the machine is divided into subdomains and in each subdomain Laplace's and Poisson's equation is solved. By expressing the magnetization functions into a difference of Heaviside functions, the demagnetization effect is accounted by the consideration of the trailing edge of a magnet having a lower value of remanent magnetic flux density. Later on, the function is being inserted on Poisson's equations and the solution is extracted in analytical form. To validate the proposed modelling technique a Two-Dimensional Finite-Element Analysis model was used. Apart from the magnetic flux density distribution the Back-EMF, cogging-torque and the unbalanced magnetic pull (UMP) were also calculated. The proposed analytical model can be used as a tool to offer quick and accurate performance calculations for the impact of demagnetization effects on surface-inset permanent-magnet machines.