Ricerc@Sapienza

A novel design of active coil shielding is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for charging the batteries of an electric vehicle (EV). The main idea is to divide the traditional active loop used to shield a source in two separate shielding coils so as not to adversely affect the WPT performance.

An innovative shielding configuration of active coils is proposed to mitigate the magnetic field around an electric vehicle (EV) with a wireless power transfer (WPT) system during battery charging. The active coil is designed to reduce the risk for patients with pacemakers or similar devices produced by the time varying magnetic field generated by the 85 kHz WPT coil currents. A numerical analysis of the magnetic field levels is carried out solving the magneto-quasi-static (MQS) equations by a FEM-based commercial tool.

A novel design of active coils is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for recharging the batteries of an electric vehicle (EV). The main idea is to split the traditional active loop, in two separate shielding coils. They have semi-annular shape and are placed on the ground pad around the WPT primary coil. The geometry and excitation of the active coils are varied to minimize the magnetic field beside the active coils without degrading the WPT electrical performance.

The shielding technique by active coils is proposed to mitigate the magnetic field produced by a wireless power transfer (WPT) system based on near field coupling. General guidelines are provided for the active shielding design to shield the source for emission reduction or to shield the victim for immunity enhancement. Then, a method is proposed to identify the suitable excitation of the active coils. The proposed method permits the mitigation of the magnetic field in a specific point or of the induced effects in a loop area.

A numerical investigation is carried out to assess the EMC and EMF safety compliance of a wireless power transfer (WPT) system used to recharge the battery of an electric vehicle (EV). The assessment is numerically performed considering a WPT system working at the frequency of 85 kHz with output power of 7.7 kW. The prediction of the electromagnetic field is carried out by using a finite element method (FEM) code to model the WPT coils and the chassis of the car.