アルミコイルを適用したSRモータに関する基礎検討

抄録

  In recent years, the development of air mobility and drones has been active. For these applications, permanent magnet (PM) motors are widely used due to their high power and efficiency. However, their cooling systems are limited to a simple air-cooling type because of size and weight limitations. Since air mobility and drones require an ultra-high power density, such insufficient cooling systems may cause irreversible demagnetization in magnets. Switched reluctance (SR) motors have no permanent magnets, consisting of only iron cores and windings, they are attracting attention as a simple, robust, and inexpensive variable-speed motor. The torque density of conventional SR motors is generally lower than those of PM motors. Hence, this paper focuses on aluminum coils, which have a higher degree of freedom of shape and are lighter than conventional copper coils. The basic characteristics of the proposed SR motor were calculated by using a three-dimensional finite element method (3D-FEM). The calculation results show that the aluminum coils are superior to the conventional copper ones in terms of torque and efficiency when the winding space factor of the aluminum coils exceeds 70%. Furthermore, the power density, which is a key indicator for air mobility, was over 1 kW/kg.