In order to achieve carbon neutrality, it is expected that electrification of various forms of mobility (mobility capabilities, means of transportation) will accelerate in the future. In this context, eVTOLs are gaining interest as the next-generation of mobility. Development of motors for eVTOLs that are smaller and of higher torque is progressing, and a motor core material that fulfills these properties is required.

Permendur YEP-2V, produced and sold by Proterial, is based on an alloy containing 50% each of iron (Fe) and cobalt (Co), with 2% vanadium (V) added to improve workability. Its composition is described as Fe-49Co-2V, and is a representative composition of Permendur. Compared to high-performance electromagnetic steel sheets (high-performance non-oriented electromagnetic steel sheets), which have attracted attention as a motor core material, Permendur YEP-2V has a higher saturation magnetic flux density and has the advantage of being able to reduce the current (applied current) required to produce the same torque. This makes it possible to reduce the size and weight of motor cores and improve energy efficiency (to address heat generation) compared to motor cores made from high-performance electromagnetic steel sheets, particularly for high-torque motor applications. In addition to the above, it has the added benefit of lower iron loss compared to general non-oriented electromagnetic steel sheets, which are the mainstream material for motor cores, allowing for higher energy efficiency.

Proterial focused on eVTOL motors, which are gaining increasing interest, and decided to evaluate Permendur YEP-2V, which has excellent properties as a core material. A motor core using the material Permendur YEP-2V was designed and prototyped^* at Proterial and installed in a motor (eVTOL mock-up motor) intended for use in eVTOLs as a demonstration test. The test demonstrated that the motor had a 14% higher torque at the same current value, and a 14% lower current at the same torque value, than a motor equipped with a motor core made from a high-performance electromagnetic steel sheet. The test also verified that the current became lower at the same torque value, so the motor generated less heat and reduced the rise in its temperature, improving energy efficiency (See 3. Evaluation motor specifications and results).

Proterial was able to confirm the excellent properties of Permendur YEP-2V as a material for eVTOL motor cores in the demonstration tests, and has therefore decided to begin full-scale proposals for its use in eVTOL motor cores. Furthermore, in addition to eVTOL motors, the company will proactively propose Permendur YEP-2V for other motors that are required to be smaller, lighter, and higher in torque, and will work towards mass production through collaborative creation with customers.

In the motor-related field, Proterial provides optimal materials and solutions, including Permendur YEP-2V as well as amorphous alloy Metglas™, neodymium magnets NEOMAX^®, ferrite magnets NMF^®, magnetic wedges, and enameled wire, to meet the needs for high performance motors, and will contribute to achieve a decarbonized society. Permendur YEP-2V and other motor-related technologies and products will be exhibited at our booth (booth number 1-T03) at Techno Frontier 2025 to be held (at Tokyo Big Sight) from July 23rd to 25th, 2025.

Yasugi Works, Specialty Steel Business Unit (Yasugi city, Shimane Prefecture, Japan)