Toshiba develops new magnetic material to improve motor energy conversion efficiency

Toshiba has developed a new magnetic material that significantly improves motor efficiency at minimal cost and has the potential to significantly reduce power consumption. The company said the material is suitable for train drive systems, automobiles, robots and other high-reliability applications.

The new material can be used as slot wedges in motors, particularly in medium and large induction motors, and can significantly improve the motor's energy conversion efficiency. Toshiba says the material can be installed at very low cost and without requiring design changes.

In an induction motor, the rotating magnetic field of the stator generates an induced current in the rotor, and the electromagnetic force generated by this causes the rotor to rotate. This system is simple to configure, low cost, and easy to maintain. In contrast, a permanent magnet synchronous motor rotates through the magnetic attraction between the rotating magnetic field of the stator and the permanent magnets of the rotor. It is usually more expensive than an induction motor, but has higher controllability and efficiency.

The company tested it on an induction motor for a railway vehicle drive system and confirmed that its efficiency was improved by 0.9%, approaching that of a permanent magnet synchronous motor. Toshiba said the material can also be installed on permanent magnet synchronous motors to achieve higher efficiency. The material also has excellent heat resistance and is suitable for applications such as railway vehicles, automobiles and robots.

(Image source: Toshiba Corporation)

The motor slot wedge is a component that tightly fixes the coil in the slot and is usually made of non-magnetic material. It has been found that the use of magnetic materials can improve the magnetic conductivity of the slot wedge, thereby improving the energy conversion efficiency. However, the conventional magnetic material used for the slot wedge, which is composed of spherical magnetic metal particles, has insufficient control over the magnetic flux and is prone to unnecessary leakage. At the same time, the magnetic slot wedge material itself has high magnetic loss and poor heat resistance, which is not suitable for railway vehicles and other applications with high heat resistance requirements.

Toshiba's new magnetic material has unique properties that enable excellent control of magnetic flux and provide high heat resistance. The material consists of flaky magnetic metal particles whose magnetic properties vary depending on the direction and have extremely low magnetic losses.

This magnetic slot wedge can effectively guide the magnetic flux to a specific direction, thereby reducing energy consumption and significantly improving energy conversion efficiency.

Toshiba also discovered that compacting flaky magnetic particles with a heat-resistant binder can improve thermal stability. Even in a high-temperature environment of 220°C, it can remain stable for a long time with almost no weight loss, paving the way for the widespread application of magnetic slot wedges.

Without changing the motor design, Toshiba significantly improved its energy conversion efficiency while minimizing costs simply by replacing the slot wedge material.