Improvement in Torque Density by Ferrofluid Injection into Magnet Tolerance of Interior Permanent Magnet Synchronous Motor †

In an interior permanent magnet synchronous motor, an adhesive such as bond is generally injected into the magnet tolerance to prevent vibration of the permanent magnet within the insertion space. In this case, a disadvantage is that the magnet tolerance does not contribute to the performance. In this paper, ferrofluid is inserted to improve the torque density, utilizing the magnet tolerance. When inserting ferrofluid into the magnet tolerance, it is important to fix the magnet because conventional adhesives are not used, and it is important that the ferrofluid does not act as a leakage path within the insertion space. In this study, a new rotor configuration using a plastic barrier that satisfies these considerations was introduced. The analysis was conducted through finite element analysis (FEA), and this technique was verified by comparing the simulation results and the experimental results through a dynamo test. It was confirmed that the no-load back electromotive force in the final model increased through ferrofluid injection.

Automated summary

This study introduces a new rotor configuration in an interior permanent magnet synchronous motor using a plastic barrier to fix the magnet and prevent ferrofluid leakage, aiming to enhance torque density through ferrofluid injection into the magnet tolerance. The analysis, conducted using finite element analysis (FEA), confirms that the no-load back electromotive force increases in the final model after ferrofluid injection, which is verified by comparing simulation and experimental results.