In the inductive power transfer systems (IPTS) of wireless electric vehicles (WEV), the electromagnetic field (EMF) should be lowered for the safety of pedestrians. In general, the EMF should be canceled for every space, time, and load condition of interest. Three generalized design methods for canceling the EMF of WEV are explained in this chapter.
By adding active EMF cancel coils to each primary main coil and secondary main coil, respectively, the EMF generated from each main coil can be independently canceled by their corresponding cancel coils. Moreover, the EMF can be successfully mitigated if a dominant EMF source only is canceled with a 3 dB margin, which can be applied to any resonant‐type wireless power transfer system. Furthermore, no significant power drop may occur if the cancel coils are placed away from the magnetic coupling path.
Design examples are shown for U‐type and W‐type IPTS as well as a wireless stationary EV charger. Experimental verifications are shown for a recently developed I‐type IPTS, which has a narrow rail width structure with alternating magnetic polarity along with a roadway. The proposed design methods have been demonstrated, without a loss of generality, to only the secondary coil, where a relatively large EMF is generated due to high ampere‐turns. An optimum spacing for cancel coils from the main coils and an optimum number of turns are determined. Through experiments, additional EMF mitigation techniques such as the magnetic mirror method, separating pick‐up rectifiers, and passive Al plate are provided. Thus, the EMF at 1 m distance from the center of a pick‐up becomes under 4.4 µT even for the maximum power of 12 kW.
This chapter is based on the paper by S.Y. Choi, B.W. Gu, S.W. Lee, W.Y. Lee, J. Huh, and C.T. Rim, “Generalized active EMF cancel methods for wireless electric vehicles,” IEEE Trans. on Power Electronics, vol. 29, no. 11, pp. 5770–5783, November 2014.
Electromagnetic Field (EMF) Cancel
2017-07-11
23 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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