Overview of analytical models of permanent magnet electrical machines for analysis and design purposes

Generally, accurate modelling of electrical machines requires the use of finite-element method. However, FE analysis is too time consuming, especially at firsts design stages, from the point of view of engineers working in R&D departments in the electrical machine industry. To reduce pre-design stages duration, analytical models are often preferred. Two types of analytical models are often used: magnetic equivalent circuits (MEC) and analytical models based on the formal solution of Maxwell's equations in constant permeability regions. However, MEC method is not as generic as the finite element method. In fact, even in the case of a given structure geometry, MEC method has to be adapted if the geometric parameters vary in a large scale. Analytical models based on the formal solution of Maxwell's equations help overcome aforementioned problem. This paper is intended as a tutorial overview based on a review of the state of the art, describing recent developments in the field of analytical modelling of permanent magnet machines.