Analytical Calculation of Magnetic Field in 2-Pole Parallel Magnetized Permanent Magnet Machines

Abstract

To obtain some performances of 2-pole parallel magnetized permanent magnet (PM) machines quickly, a subdomain method to calculating the open-circuit magnetic field in such machines is proposed. According to material and structural characteristics, we can divide the solution region into three parts having regular shapes. The permanent magnet is the first subdomain and the air-gap is the second subdomain and the stator slots is the third subdomain. Each subdomain is expressed by corresponding governing function in polar coordinate system. The governing functions in those subdomains are solved by variable separation method to obtain the expressions of vector potential distribution and then the field solutions are obtained using interface conditions between the subdomains. Taking a 2-pole/12-slot parallel magnetized prototype permanent magnet machine as example, the flux density in each subdomain is solved via the proposed subdomain method and the predictions are validated through corresponding finite element (FE) method. The verification results illustrate that the subdomain method can solve the open-circuit magnetic field precisely in slotted 2-pole parallel magnetized PM machines.