Active EMF cancellation method for I-type pickup of On-Line Electric Vehicles

Abstract

In the Inductive Power Transfer System (IPTS) for the On-Line Electric Vehicle (OLEV), the Electro Magnetic Field (EMF) should be lower than 62.5 mG at 20 kHz for the safety of pedestrians. To meet the EMF requirement a new active EMF cancel method for the recently developed I-type IPTS is proposed in this paper. The I-type IPTS has a narrow rail width structure with alternating magnetic polarity along with a roadway. The EMF canceling is applied to only pick-up where large EMF is generated due to large ampere-turns. An optimum spacing for cancel coils from main coils is found, and an optimum canceling architecture is also proposed. Experiments for various conditions such as cancel coil turns, size, configuration, and rectifier connection verify that the canceling strategy on the IPTS for OLEV proposed in this paper is quite practical. The EMF at 1 m distance from the center of pick-up is always under 50 mG for maximum power condition.