# Fileset

[REPM2025_P1-39_Takeda.pdf](https://mdr.nims.go.jp/filesets/a4dc64b2-cff9-4201-bbff-e05b622f6652/download)

## Creator

Kenji Takeda, R. Fujiwara, T. Shinji, S. Miyazaki, T. Kajita, Y. Enokido, K. Akatsu

## Rights

[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[Dynamic evaluation in motors of variable magnetic flux magnets](https://mdr.nims.go.jp/datasets/50b395fa-e67b-4804-96b5-d85a27de8b4b)

## Fulltext

A0_ver1L2: Internal use onlyDynamic evaluation in motors of variable magnetic flux magnetsK. Takedaa*, R. Fujiwaraa, T. Shinjia, S. Miyazakia, T. Kajitaa, Y. Enokidoa, K. Akatsuba Technology and Intellectual Property HQ, TDK Corporationb Department of Faculty of Engineering, Yokohama National UniversityThe variable magnetic flux permanent magnet synchronous motor(VMF-PMSM) is expected to achieve high efficiency over a wideoperating range by switching the magnetization states of the VMF-magnet. To achieve the desired torque, the relationship betweenthe electrical control and the operating point of the VMF-magnetshould be grasped. This presentation will show the approach fordirectly measuring the operating point of the VMF-magnet.Background and Objective•VMF-PMSM system with real-time measurement was developed.•Since the experimental magnetic flux density do not necessarily explain the behavior of magnet torque,further investigation is needed to clarify the deviations.Conclusion[1] K. Takeda, S. Miyazaki, T. Kajita and Y. Enokido, IEEE Transaction on Magnetics, 59, 8203105 (2023).MethodsResultsThe rotor magnet consisted of a series lamination of the VMF-magnet [1] and the high coercive field magnets. Due to coil magnetic field limitations caused by inverter capacity, the VMF-magnet was used in a low magnetic saturation state.To operate the VMF-PMSM, a controller (PE-Expert3) and an inverter (MWINV-2022A) manufactured by Myway Plus Corp. were used.The sensor probe with a Hall element and an NTC thermistor was installed on the magnet surface opposite the gap to minimize the influence of the coil magnetic field. The sensor was electrically connected to a signal conditioner mounted on the rotor shaft, which includes a coin cell, a micro-controller, and a Bluetooth module for measurement and wireless communication.ResultsVMF-magnet is magnetized and demagnetized by d-axis current of ±60 A (β = ∓90 deg) during50 ms during a 600 rpm rotation at 26℃.Real-time flux density changes due to magnetization and demagnetization of a VMF-Magnet can be observed.The magnet torque at rated operation of 3 A in High J state at β = 0 deg decreased by 3.8% after a field weakening operation up to β = 90 deg, which corresponded to a 4.0% decrease in the magnet magnetic flux density,while the magnet torque in Low J state decreased by 0.12% after a field weakening operation, which deviated from 2.5% decrease in the magnet magnetic flux. スライド 1