Magnetic circuit analysis of permanent-magnet-assisted salient-pole synchronous machines under steady states

Permanent-magnet-assisted salient-pole synchronous machines (PMa-SMs) are a new type of salient-pole synchronous machines that has permanent magnets (PMs) between the adjacent pole shoes. The PMs have ability to improve the output power and the terminal voltage. In this paper, a simple magnetic circuit of PMa-SMs is presented. Using the magnetic circuit, the electric and magnetic basic characteristics of PMa-SMs are calculated. The results are compared with the results by measurements and finite element analysis (FEA). They have shown that the magnetic circuit calculates the characteristics of PMa-SMs with satisfactory accuracy and that the computational time of the magnetic circuit is much smaller than that of FEA. Causes of small differences between the results of the magnetic circuit and the measurements are also discussed and some guidelines to improve accuracy of the magnetic circuit have been presented.