Star-Shaped Coils in the Transmitter Array for Receiver Rotation Tolerance in Free-Moving Wireless Power Transfer Applications

Abstract

Wireless power is one of the new promising technologies for IoT applications. The use of arrays for power transfer to free-moving objects has revolutionized wireless power transmission (WPT) applications. Herein, we present an extendable platform for transmitting power to a moving object receiving power from an array. The transmitter (TX) consists of two overlapping layers of square planar coils rotated 45 degrees to each other to provide the best electromagnetic flux coverage. Each layer consists of four coils to further control the power supply to the small receiver (RX) coil. This overlapping star-shaped array is stimulated automatically by a power amplifier. This smart stimulation can deliver uniform power to the receiver regardless of rotation and misalignment inconsistencies by using the geometry of the transmitter array. Moreover, by changing the direction of the current of each small square component in each array using the flower-shaped current, a receiver coil perpendicular to the transmitter’s plate can obtain power comparable with conventional structures. We use ADS-HFSS simulation to verify the fabrication and measurement results. The proposed transmitter achieves an average of 18.2% power transfer efficiency (PTE) to RX and at 90° angular misalignment, 11.5% PTE, while the conventional structure transfers no power to the perpendicular RX coil. A future application of the transmitter can be the investigation of the neurobehavioral of free-moving animals and brain–machine interface studies in medicine.