Technical Development of Electro Magnetic Compatibility for Plug-in Hybrid Vehicle / Electric Vehicle Using Wireless Power Transfer System 2016-01-1161
In 2007, researchers at the Massachusetts Institute of Technology successfully completed a Wireless Power Transfer (WPT) experiment. Ever since, interest in WPT has been growing. At Toyota, we have been developing the underlying technology of a WPT system. Simultaneously we have been working with regulatory committees to create a standard for WPT. In particular, there are concerns that WPT’s radiated emissions could cause harm to humans and the neighboring electronic equipment. There are many challenges that need to be overcome, but a key concern is understanding WPT’s electromagnetic compatibility (EMI: Electro-Magnetic Interference and EMF: Electro-Magnetic Field). In this paper, we show the technical issues, the evaluation method, and the development status of EMI and EMF on PHVs/EVs when using WPT.
For Electromagnetic interference (EMI) performance, we investigated both an open area test site and an electromagnetic anechoic chamber as evaluation environments. Through these tests, we found that we could evaluate the fundamental frequency of WPT’s radiated emissions at an open area test site. In addition, we found that we could evaluate the harmonics of WPT in an electromagnetic anechoic chamber.
We developed some countermeasure materials made of different magnetized materials to reduce the fundamental frequency’s radiated emissions. As a result, we confirmed that higher magnetic permeability materials have larger effects to reduce the fundamental frequency’s radiated emissions.
To address EMF concerns, we investigated the possibility that the human body and active implantable medical devices were affected by the radiated emissions of WPT. We introduced an evaluation method to investigate these claims using a torso phantom. Our results found no adverse effects to the human body or active implantable medical devices (AIMD) and that users can use WPT safely.