In-Vehicle Sensing System to Sense the Ground Pad Configuration in the V2G Mode of EV

Abstract

This paper presents a sensing system in the vehicle pad that detects the ground pad type and helps to enable the vehicle-to-grid (V2G) operation of an electric vehicle (EV). In this work, two commonly used vehicle pad types, i.e. circular pad (CP) and double-D pad (DDP) are considered together with bipolar pad (BPP) ground pad. BPP has to be correctly configured to magnetically couple to CP or DDP type pads in the EV. Otherwise, the efficiency of V2G wireless power transfer will be very low. It will be highly beneficial if a simple scheme is available that can independently sense the ground pad configuration from the vehicle side. The proposed system senses the change in the magnitude and spatial pattern of the magnetic field directly below the vehicle pad and reliably detects the ground pad and senses the configuration of it. During sensing, the vehicle pad is excited at a very low current at the resonance frequency of the pad, and the magnetic field is observed using magnetoresistance (MR) sensors integrated in the vehicle pad. The magnitude of the field changes, mainly, due to the frequency bifurcation effect (FBE) while the field pattern gets modified due to the induced current in the ground pad. A prototype of the proposed system was built in the laboratory and tested and its performance was evaluated. The results showed that the BPP ground pad configuration can be reliably sensed from the vehicle side, for both CP and DDP types of vehicle pads, thus validating the functionality and practicality of the proposed approach and the sensing system.