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## Graduate School of Science and Engineering

Electrical and Electronic Engineering

### Electrical Machinery & Apparatus Laboratory

#### Staff

Yasuhito TAKAHASHI

[Associate Professor]

Telephone : +81-774-65-6266

Office : YE-317

Database of Researchers

#### Research Topics

- Analysis and design of electric machines such as transformers, inductors, actuators, generators and motors
- Development of numerical methods for magnetic field analyses and modelling methods for magnetic hysteresis and anisotropy
- Measurement of magnetic properties of power magnetic materials under various excitation conditions
- Presumption of factor affecting output power deterioration in crystalline silicon PV modules
- Bidirectional battery-charging/discharging system
- High-efficiency wireless power transfer system based on resonant DC-DC converters

#### Research Contents

We investigate high-efficiency technologies of electric machines and electronic circuits, enhancement of their control methods, efficient use of renewable energy. The common concept of our research projects is “saving energy.”

1. Performance analysis and design optimization of electric machines

Magnetic field analysis

Nowadays, magnetic field analyses are widely used in designing electric machines thanks to performance improvement of computers and development of novel numerical methods. We develop numerical techniques based on finite element methods and practical modelling methods for magnetic properties, and carry out magnetic field analyses of various electric machines to achieve their optimal design.

Magnetic properties of soft magnetic materials

In order to make the best use of electrical steel sheets in designing high-performance electrical machines, it is indispensable to deeply understand their magnetic properties. We investigate magnetic measurement methods for soft magnetic materials under alternating/rotating, sinusoidal/non-sinusoidal magnetic flux conditions from low- to high-frequency region.

2. Photovoltaic power (PV) system

From the standpoint of efficient use of solar power, we investigate optimal design method/performance evaluation method for PV system, control algorithm of maximum power point tracking (MPPT), solar irradiation forecast, and estimation of factor affecting output power deterioration in PV modules.

3. Power electronics

Switching-mode power supply

Switching-mode power supply, which was developed for downsizing and efficiency improvement of power circuits, is based on switching semiconductor at higher frequencies to control electric power flow. We apply various soft switching techniques to DC-DC converters to achieve higher operating frequency and higher efficiency.

Various techniques related to electric vehicle (EV)

Recently, the interest in EVs is increasing drastically. We develop bidirectional battery-charging/discharging system for EVs, and investigate high-efficiency wireless power transfer system based on resonant DC-DC converters and control methods for driving motors and power electronics circuits with FPGA/DSP.

4. Electromagnetic environment

Recently, electromagnetic noise generated from various electronic devices and electric machines is one of the big issues. We investigate electromagnetic noise generating mechanism based on experiments and computer simulations, and develop novel power circuit system to suppress noise generation.

1. Performance analysis and design optimization of electric machines

Magnetic field analysis

Nowadays, magnetic field analyses are widely used in designing electric machines thanks to performance improvement of computers and development of novel numerical methods. We develop numerical techniques based on finite element methods and practical modelling methods for magnetic properties, and carry out magnetic field analyses of various electric machines to achieve their optimal design.

Magnetic properties of soft magnetic materials

In order to make the best use of electrical steel sheets in designing high-performance electrical machines, it is indispensable to deeply understand their magnetic properties. We investigate magnetic measurement methods for soft magnetic materials under alternating/rotating, sinusoidal/non-sinusoidal magnetic flux conditions from low- to high-frequency region.

2. Photovoltaic power (PV) system

From the standpoint of efficient use of solar power, we investigate optimal design method/performance evaluation method for PV system, control algorithm of maximum power point tracking (MPPT), solar irradiation forecast, and estimation of factor affecting output power deterioration in PV modules.

3. Power electronics

Switching-mode power supply

Switching-mode power supply, which was developed for downsizing and efficiency improvement of power circuits, is based on switching semiconductor at higher frequencies to control electric power flow. We apply various soft switching techniques to DC-DC converters to achieve higher operating frequency and higher efficiency.

Various techniques related to electric vehicle (EV)

Recently, the interest in EVs is increasing drastically. We develop bidirectional battery-charging/discharging system for EVs, and investigate high-efficiency wireless power transfer system based on resonant DC-DC converters and control methods for driving motors and power electronics circuits with FPGA/DSP.

4. Electromagnetic environment

Recently, electromagnetic noise generated from various electronic devices and electric machines is one of the big issues. We investigate electromagnetic noise generating mechanism based on experiments and computer simulations, and develop novel power circuit system to suppress noise generation.

#### Keywords

- Electric machine
- Magnetic field analysis
- Finite element method
- Material modeling
- Standard measurement method for magnetic property
- Single sheet tester
- Electrical steel sheet

- Magnetostriction
- PV system
- MPPT method
- Image diagnosis
- DC-DC converter
- Wireless power transfer system
- Electromagnetic noise