A Smart Primary Pad with Integrated TMR Sensors for Wirelessly Charged EVs

Technology: Smart Primary Pad with Integrated TMR Sensors;

Industry & Application: Electric Vehicle (EVs);

Market: The global TMR sensor market is projected to grow at a CAGR of 3.5% during 2024-2029.

In prior art literature survey, it is noted that Wireless power transfer(WPT) using an inductive power transfer (IPT) technique has been finding its application in the EV.
One of the main challenges faced in the lumped Inductive power transfer (IPT), highway design is the detection of EVs as they travel over the IPT highway.
Only that primary coil with sufficient coupling with the secondary coil on the EV needs to be energized. To mitigate the above challenge, a suitable sensing mechanism is required. Hence, there is a need to address said issues effectively in efficiently.

Present invention describes a simple method and a IPT system to detect EVs’ secondary coil on IPT highways, & further said IPT system enables charging the vehicle while moving on the road.
The IPT system includes one or more primary coil; secondary coil, installed on a body part of the vehicle; the IPT highway path, one or more sensor are placed over the trailing edge of the primary coil, & the leading edge of the primary coil to measure a magnetic field generated by the detection coil.
The method comprises a few steps shown in the smart chart herein:

In this instant, a tunneling magnetoresistance (TMR) sensor based EV detection method on an IPT highway is proposed where in a detection coil is wound around an outer boundary of the secondary coil.
TMR sensors sense the magnetic field generated by the detection coil.
The TMR sensors are placed over the leading & trailing edges (in the direction of EV travel) of the primary coil, & from the leading edge TMR sensor outputs, the energization point of that primary coil to begin IPT, is decided.
Similarly, from the trailing edge TMR sensor outputs, the de-energization point to stop IPT from that primary coil, is decided.

Technical Perspective:

The detection coil is wound around an outer boundary of the secondary coil & the detection coil is excited at 400 kHz.
The duration of the energizing the primary coil is determined from the TMR sensor outputs, & the duration for which there is an area of overlap between the primary & secondary coils of at least 50%.
Claimed system enables the driver of the EV in correcting the lateral misalignment so that efficient charging is possible from the subsequent primary pads.
There was negligible error introduced in the final output due to angular misalignment between the charging lane & the vehicle.
The sensor system could detect the presence of metallic plates lying on the road in such a way that some of the sensors on the sensor pad are covered.
The response time was found out to be around 7.5µs & with this response time, the system works for the usual vehicle speeds encountered.
The proposed system is based on magnetic sensing, its performance is not affected due to dust, snow, oil and humidity.

Industry Perspective:

Applicable in the area of Electric vehicles, usage in commercial vehicle, Public vehicle & etc.

Prof. Boby George

Department of Electrical Engineering

TRL-4

Proof of Concept ready, tested in lab.

Technology Transfer