Investigation of magnet arrangements in double layer interior permanent-magnet motors

In this paper, we investigate the best magnet arrangement and appropriate circuit parameters in double layer interior permanent-magnet motors for high speed applications using flux-weakening control. First, the characteristics of the several motors with the double layer magnet arrangements are compared by the finite element method, for example, straight type, V type, and their combination. Next, the appropriate magnet arrangement and the circuit parameters of the motors are discussed from the viewpoints of wide operating range and high efficiency. Finally, the characteristics of the proposed motor are verified by the measurement. It is clarified that the motor with the triangle magnet arrangement, which is the combination of the straight and V type, is suitable for high speed and high power applications.