Reducing Electromagnetic Leakage from WPT Systems

ワイヤレス給電における伝送電力の増大に伴い, 漏洩磁界の増加が大きな課題として認識されている. 送受電器近傍では人体防護, 送受電器遠方では電磁両立性といった観点から, 漏洩磁界を抑制しなければならない.
近傍の漏洩磁界抑制に向けては, 負荷インピーダンスの値が漏洩磁界の主要因であることを明らかにし, 高い伝送効率を維持しつつ漏洩電磁界強度を抑制できる負荷インピーダンスを解析的に導き, 送受電器近傍での磁界強度を20%以上削減できることを明らかにしている.
遠方の漏洩磁界抑制に向けては, 送電器アレイと受電器から発生する漏洩磁界が各コイルに流れる電流の線形和で定式化可能であることに着目し, 漏洩磁界を打ち消しながらも, 高い伝送効率を維持できる入力電流を理論的に導き, 送受電器から10m離れた遠方での磁界強度を90%以上削減できることを明らかにしている.


EM leakage from wireless power transfer (WPT) increases rapidly due to the demand for large transmission power. In this research, we are working on suppressing 1) EM leakage near resonators for body protection as well as 2) EM leakage far from resonators for EMC.
As the method for EM leakage near resonators, we first show that the load impedance significantly affects the EM leakage, and then formalize the load impedance which minimizes EM leakage while maintaining high transfer efficiency. The simulation results confirmed that the EM leakage can be reduced by about 20%.
On the other hand, for EM leakage far from resonators, we formulate the EM leakage from a transmitter array to a receiver and theoretically derived a method that maximizes the transmission efficiency while canceling the leakage about 90%.