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Disk coreless PM synchronous motor achieves rapid development due to its excellent performance in recent years. It has many advantages of a short axial length, a compact structure, a small volume and weight, a low moment of inertia, no excitation losses, no core losses, a high efficiency, a fine cooling condition, a high power density, a high torque, a high ratio of torque to mass, smooth running at low speed, a ascendant dynamic performance and so on. Servomechanisms, in which disk coreless PM synchronous motors are involved as execution modules, have been widely utilized in systems of high precision such as numerical control machine tools, robots and radars.Disk coreless PM synchronous motors of average airgap structure, wedgy airgap structure and multi-airgap structure have been developed inland, and Halbach PM array has been applied in the design of these electric machines, effectively advancing their performance. A design process has so far been summarized as experience in designing disk coreless PM synchronous motors accumulates. Nevertheless, parameter calculation method that suits these electric machines still needs to be researched, since a disk coreless PM synchronous motor is entirely different from a cylinder machine in structure.As a part of the 863 national project“Technology integration and pivotal materials for high performance rare earth PM machines”, this paper focuses on the parameter calculation method of disk coreless PM synchronous motors. Parameter calculation based on FEM, by which the distribution of magnetic field and currents in an electric machine can be well and truly simulated and the results of which are more accurate, is proposed in this paper. FEM based calculation of synchronous reactance, calculation arc coefficient, electromagnetic torque and EMF is narrated in this paper.
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