University students using JMAG in their research will present their achievements in posters.

Come and see what they are working on and how JMAG is used in their research.

Stop by to hear the presentations and hold discussion with the students.

Order of application received

**A Study of large-scale electromagnetic field analysis of large-scale magnetic gears for offshore wind power generation**

Nakamura laboratory, Department of Management Science and Technology, Graduate School of Engineering, Tohoku university

Mr. Akira Kudo

**Fringing Loss Analysis of Large Capacity Inductors**

Kosaka-Matsumori Laboratory, Nagoya Institute of Technology

Mr. Norifumi Kobayashi

**Parametric optimization of Magnetic Worm-Geared Motor with half skew structure to improve torque density**

Tsutsui Endo Laboratory, Department of Electrical and Electronic Engineering, School of Engineering, Institute of Science Tokyo

Mr. Haruki Yamanaka

**Variable Magnetomotive Force Memory Motor Drive System with Resonant Magnetization Windings to Reduce the Current Load on Power Semiconductor Devices**

Power Electronics Laboratory, Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University

Mr. Manari Mizuno

**A Study of an Axial-Flux PM Motor using SMC for Drones**

Nakamura laboratory, Department of Management Science and Technology, Graduate School of Engineering, Tohoku University

Mr. Shogo Suzuki

**The Identification of Shape Functions in Play Models Using Rational Polynomial Approximation**

Electromagnetics Application Lab, Electronic Engineering, Graduate school of Science and Engineering, Kindai University

Mr. Naoto Tanimoto

**Wireless Power Transmission Technology in Electrically Excited Synchronous Motor**

Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

Mr. Yuta Toyoda

**Optimized Designs of Multi-phase Multi-mode Reluctance Motors considering Current Vector Control**

Chiba Kiyota Laboratory, Department of Electrical and Electronic Engineering, School of Engineering, Institute of Science Tokyo

Mr. Ryo Kokubu

**Design of a Wound Field Flux Switching Motor that can be switched to a Synchronous Reluctance Motor using coupled analysis**

Chiba Kiyota Laboratory, Department of Electrical and Electronic Engineering, School of Engineering, Institute of Science Tokyo

Mr. Iori Kokubo

**Investigation of dq-axes Inductance and High-frequency Current Response considering to Cross-coupling Term in Sensorless Control for SynRM with Large Magnetic Saturation**

Power Electronics Laboratory, Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University

Mr. Sota Takizawa

**A Study of large-scale electromagnetic field analysis of large-scale magnetic gears for offshore wind power generation**

In recent years, growing interest in natural energy has promoted the use of offshore wind power generation. However, mechanical gears face maintenance problems due to friction and heat generation. In contrast, non-contact magnetic gears are expected to be the next generation of gears because they inherently generate less vibration, noise, and dust, making them easier to maintain.

Among various types of magnetic gears, flux-modulated magnetic gears are the most promising for practical applications due to their high torque density and efficiency, as all magnets in the inner and outer rotors constantly contribute to torque transmission. On the other hand, since permanent magnets are used in both the inner and outer rotors, reducing the amount of magnets while maintaining performance is crucial.

The diameter of magnetic gears used in offshore wind turbines can reach approximately 10 meters, making it challenging to optimize the magnet geometry using 3D electromagnetic field analysis by FEM due to the model size.

Therefore, this study investigates the optimization of magnet geometry using large-scale parallel computation with a supercomputer, aiming to improve torque characteristics and reduce the amount of magnets in large magnetic gears for offshore wind turbines.

**Fringing Loss Analysis of Large Capacity Inductors**

The proliferation of electric vehicles (BEVs) and hybrid vehicles (PHEVs) has led to an expectation that the inductors utilized in these vehicles will be subjected to increasingly elevated power levels. In inductors that are operated at high power, it is standard practice to insert an air gap in order to prevent magnetic saturation of the magnetic core. However, the introduction of an air gap results in a complex alteration of magnetic resistance, with magnetic flux escaping from the gap and extending to the exterior of the core, thus generating fringing magnetic flux. The Joule loss (fringing loss) caused by this fringing flux complicates the loss characteristics of the inductor and makes the evaluation of losses in large-capacity inductors challenging. This study aims to explore a system for more accurate evaluation of inductor losses that takes fringing losses into account, using JMAG-Designer.

**Parametric optimization of Magnetic Worm-Geared Motor with half skew structure to improve torque density**

Weight reduction of actuator is required for Cobot which operates without fence, because it leads to increase in speed and easiness of changing the layout of Cobot.

Therefore, aiming at developing higher torque density motor, this research proposed Magnetic Worm-geared Motor (MWGM) imitating worm gear. Previously, its torque density was improved by introducing claw pole and half skew structure, but the torque density needs to be improved more.

In this presentation, parametric optimization is applied to MWGM with half skew structure. To reduce the calculation cost, objective function is set to maximize no-load flux density which enables use of static analysis. To reduce partial saturation, slope is introduced to claw yoke by making use of “boolean” function of JMAG-Designer. Comparison of analysis result shows that optimization improves torque density.

**Variable Magnetomotive Force Memory Motor Drive System with Resonant Magnetization Windings to Reduce the Current Load on Power Semiconductor Devices**

Permanent Magnet Synchronous Motors (PMSM) require flux weakening control during high-speed rotation, and the resulting copper loss and resulting efficiency drop is a problem. To solve this problem, Variable Magnetomotive Force Motors are being researched. The VMFM has the problem of increasing the rated power of the power semiconductor device and the margin of the drive voltage for direct current voltage, because a large magnetisation current is momentarily passed when the magnetisation state of the variable magnetomotive force magnet is changed. In response to the above issues, this report proposes a variable magnetic force memory motor drive system with a magnetisation-dedicated coil that uses a resonant circuit, and reports on the results of the verification by simulation.

**A Study of an Axial-Flux PM Motor using SMC for Drones**

Drones are expected to be used in a wide range of fields, including agriculture, inspection and maintenance, and logistics. Therefore, the market size is expected to expand in the future. Accordingly, the motors used in the drones are required to be light, thin, and small, and to provide the desired torque. Although the axial flux motor is known as a motor structure that is suitable for flat motors, its manufacture has challenges due to the complexity of its stator core. This complexity makes it difficult to use conventional electrical steel sheets. Therefore, in this study, an axial flux PM motor for drones was analyzed and designed by applying a soft magnetic composite (SMC), which can be made into complex shapes, to the stator core. In designing the motor, the motor’s electromagnetic analysis was done using the finite element method (FEM). Furthermore, parts of the motor were optimized by using a genetic algorithm (GA) with the aim of maximizing the torque-to-weight ratio. The 2D linear models were adopted since the optimization time for 3D models would be long. The result revealed that the torque-to-weight ratio of the designed motor was approximately 25% higher than that of a radial flux PM motor of the same volume.

**The Identification of Shape Functions in Play Models Using Rational Polynomial Approximation**

For the high efficiency of electrical machines, accurate iron loss estimation is essential. To achieve this, magnetic field analysis considering the hysteresis properties of magnetic materials is effective. The play model, which represents arbitrary hysteresis loops by combining multiple play hysterons with shape functions, is widely used as a model to realize hysteresis characteristics. The shape functions used in play models require the magnetic flux density to be evenly distributed. However, precisely controlling this in measured data while capturing many loops is not easy and requires an extended period of time.

In this poster, we propose a method to obtain shape functions by performing parametric rational polynomial approximation on the measured hysteresis properties, allowing for the interpolation of minor loops. This method enables the creation of evenly distributed play models from unevenly spaced measured data, allowing for the construction of play models based on relatively few measured data points.

**Wireless Power Transmission Technology in Electrically Excited Synchronous Motor**

High efficiency characteristics in all operation ranges are required for traction motors of EVs. In order to satisfy this requirement, an electrically excited synchronous motor (EESM) is focused. It may be possible that the EESM satisfies high efficiency characteristics in all operation ranges. Nowadays, EESMs using a slip ring is in mass production. However, the size increases in the axial direction due to the slip ring. In my study, I focus on an EESM that a wireless power transmission is applied. In this presentation, the wireless power transmission is mathematically described, and the design technique is investigated using JMAG-Designer.

**Optimized Designs of Multi-phase Multi-mode Reluctance Motors considering Current Vector Control**

A multimode reluctance motor (MRM) can switch its driving mode between Synchronous Reluctance Motor and Switched Reluctance Motor with a minimum of control freedom in a single housing. In particular, a five-phase MRM with 12-pole 20-slot for a traction motor of a hybrid electric vehicle (HEV) was designed in terms of both mechanical geometry and current waveform. This was conducted using a single-objective genetic algorithm with the maximization of maximum torque as the target function.

Furthermore, seven-phase MRMs with 6-pole 14-slot and 10-pole 14-slot were also considered as the candidates. This presentation outlines the methodology and outcomes of each case for the optimized designs of multiphase MRMs considering current vector control.

**Design of a Wound Field Flux Switching Motor that can be switched to a Synchronous Reluctance Motor using coupled analysis**

This study aims to improve the performance of a Wound Field Flux Switching Motor (WFFSM) that can be switched to a Synchronous Reluctance Motor (SynRM). Therefore, it is necessary to consider not only the WFFSM operation but also its characteristics when driven as a SynRM. However, in previous designs, the approach is based solely on maximizing the torque of WFFSM operation at the base rotational speed. So, there are problems with areas of extreme efficiency deterioration in the high speed range of WFFSM operation and sudden torque reduction in the high speed range when SynRM operation is used. Therefore, we report that by using the coupled analysis function, it is possible to design the motor while considering the performance of both WFFSM and SynRM operations.

**Investigation of dq-axes Inductance and High-frequency Current Response considering to Cross-coupling Term in Sensorless Control for SynRM with Large Magnetic Saturation**

In recent years, the use of synchronous reluctance motors (SynRM), which are capable of high efficiency and do not use permanent magnets in the rotor, has been expanding due to the growing momentum for energy and resource conservation. When vector control is performed using sensorless control with this SynRM, the effect of inductance changes on the error in estimating the magnetic pole position is significant due to the characteristic of large magnetic saturation, making it difficult to perform high-precision magnetic pole position estimation. To solve this problem, sensorless control methods that can handle the nonlinear characteristics and harmonic components caused by magnetic saturation are being researched. In this report, we compare and verify the results of using the magnetic flux analysis of the JMAG-RT model and the results of actual machine verification for the characteristics of the high-frequency current response when there is an effect of magnetic saturation, considering the saturation characteristics and the effect of axial interference.