Research

WPT

Welcome to Electromagnetic Compatibility LAB

Wireless power transfer system for biomedical
  • Various of implantable medical device(IMD)

  • Concept of the IMD with wireless power transfer technology (a) pacemaker, (b) Deep brain stimulator

As the effectiveness of an implantable medical device such as an artificial pacemaker, neuro-stimulator, or cochlear implant has been proven, it is widely used to treat various diseases. However, such an implantable medical device has a number of problems. The biggest problem is the battery. The battery life of implantable medical devices ranges from two to five years, that is, they need to be replaced every two to five years. In addition, complex structures can damage internal parts of the human body or cause necrosis of surrounding tissues. In order to solve the limitations of the implantable medical device, we are studying the application of wireless power transfer technology to the implantable medical device.In our laboratory, we are focusing on miniaturization of coils, securing safety (heat and electromagnetic wave effects), and improving stimulus performance to apply wireless power transfer technology to pacemaker and neuro-stimulator. The convergence of wireless power transfer technology with biomedical technology, a key field of the fourth industry, can lead the technological development.

Wireless power transfer system in conductive medium

In recent years, the wireless power transfer technology is mainly focused on the inductive coupling method using time-varying magnetic field. Unlike in air, however, time-varying magnetic fields generate eddy current in conductive medium such as seawater. Therefore, new coil modeling method for eddy current loss analysis in conductive medium is being studied.
As WPT(wireless power transfer) technology is improved, attempts to apply it to various applications are increasing. Recently, WPT has been used for the purpose of supplying power to underwater robots that perform construction, resource exploration, and military operations.
Research of WPT mainly focused on the inductive coupling method using time-varying magnetic field. Unlike in air, however, time-varying magnetic fields generate eddy current in conductive medium such as seawater. Therefore, new coil modeling method for eddy current loss analysis in conductive medium is being studied.

Wireless power transfer system for UAVs (Unmanned Aerial Vehicles)
  • WPT for UAVs (200 W)

  • WPT for drone (400 W)

Recently, unmanned aerial vehicles (UAVs) have been used in various fields such as military, hobby, and industry. There are various types of UAVs such as drones and missiles. Among them, the use of drones becomes particularly important.
We are studying on applying a wireless power transfer system to replace the wired charging system previously adopted in conventional UAVs. The power capacity of the application ranges from tens of W to hundreds of kW, and we are designing power circuits as well. If wireless power transfer system is applied to UAVs, it is expected that UAVs will be actively used in various fields.

Wireless power transfer system for Electric Vehicles
  • WPT for Electric vehicles (15 kW)

  • WPT for AGVs(Automated Guided Vehicle) (4 kW)

Recently, unmanned aerial vehicles (UAVs) have been used in various fields such as military, hobby, and industry. There are various types of UAVs such as drones and missiles. Among them, the use of drones becomes particularly important.
We are studying on applying a wireless power transfer system to replace the wired charging system previously adopted in conventional UAVs. The power capacity of the application ranges from tens of W to hundreds of kW, and we are designing power circuits as well. If wireless power transfer system is applied to UAVs, it is expected that UAVs will be actively used in various fields.

Magnetic energy harvesting system
  • Concept of magnetic energy harvesting system

  • Design of magnetic core

  • Guideline of Soft Magnetic Material

  • Harvester connection

Power system requires constant inspection and preventive maintenance for proper fault-free operation. There are various devices to monitor and maintain the longevity of power system have been developed such as wireless sensors, brachiating robot, and so on. Most devices heavily rely on the battery which has a finite life span and is expensive to replace periodically. For this reason, magnetic energy harvesting is a promising technologies for self-sustainable operation of devices around power line. However, the magnetic energy harvester has a problem that magnetic core material is saturated at high current condition.
In our laboratory, we focus on the design of magnetic core with improved power density under the saturation condition. We verify the proposed modeling using Maxwell 3D EM simulation and measurement of the fabricated magnetic core using B-H Curve tracer. Furthermore, we actually implemented magnetic energy harvesting system to demonstrate in distribution system(22.9kV).

Optimal driving method with multiple TX Coils
  • Schematic of a multiple transmitters WPT system

  • Circuit model of a multiple transmitters WPT system

Wireless power transfer (WPT) technology has been used in various applications such as smart phones, drones, pacemakers, and electric vehicles. However, when misalignment occurs, the efficiency decreases drastically. In order to solve this problem, usually a larger diameter transmitter(TX) coil is used to cover wide area. However, this approach has several drawbacks such as centralization of magnetic field and increasing EMF(Electromagnetic Field) problem. Therefore, we propose multiple TXs system that can make wide magnetic field uniformly and select optimal TX(s) to decrease power loss and EMF problem.

In our laboratory, we propose an optimal transmitter selection method for maximum power transfer efficiency that is robust against misalignment. Furthermore, we have plans for researches about receiver detecting method, EMF, EMI reduction method in WPT system using multiple coil, and so on.