Tadashi Sonobe, Research and Development Center, MAYEKAWA MFG.CO.,LTD., Kinya Fujita, Electrical Products Mfg. Div., MAYEKAWA MFG.CO.,LTD.
It has been an important subject as ever for some IPMSM to draw out its generated torque in a small quantities of the rare earth magnet due to save its resources although its cost pulling back to the former one. In spite of the same outer dimensions, IPMSM, exposed in a special refrigerant, will be required to comparable performance such as a generated torque, torque ripple and efficiency to original ones with reducing the used magnet amount. It will be realized, for example, by changing 12s8p (12slots8poles) to 9s6p of rotor structure, reducing the amount of magnet pieces 8 to 6.The distance between the magnets are enlargen to 0.5～1 of magnet length. With the void space between the magnets expanding, reluctance torque will be added to magnet torque. A pair of T-butterfly void is proposed, which had T bridge-stay structure that cut the gradually curved shape consisting of the continuous and differentiable curves that avoid angle direction component of stress working on the bridge pieces due to centrifugal force with a rotor silicon steel sheet surrounding the cavity, besides SUS plates added. Typical optimal design of structure is shown and confirmed its effectiveness by JMAG finite element methods. Centrifugal force-resistant analyses are also done and confirmed the effectiveness of its structure by DS module.