An Innovative Design of In-Tire Energy Harvester for the Power Supply of Tire Sensors 2018-01-1115
With the development of intelligent vehicle and active vehicle safety systems, the demand of sensors is increasing, especially in-tire sensors. Tire parameters are essential for vehicle dynamic control, including tire pressure, tire temperature, slip angle, longitudinal force, etc.. The diversification and growth of in-tire sensors require adequate power supply. Traditionally, embedded batteries are used to power sensors in tire, however, they must be replaced periodically because of the limited energy storage. The power limitation of the batteries would reduce the real-time data transmission frequency and deteriorate the vehicle safety. Heightened interest focuses on generating power through energy harvesting systems in replace of the batteries. Current in-tire energy harvesting devices include piezoelectric, electromagnetic, electrostatic and electromechanical mechanism, whose energy sources include tire deformations, vibrations and rotations. Through comparison, in-tire energy harvesting systems on basis of the electromagnetic induction principle have the advantage of relatively high energy density. Based on electromagnetic induction, this paper designs a novel design of in-tire energy harvester, taking use of the tire deformation when the tire contacts the ground. This paper describes the innovative design and builds the simulation model of magnetic field, integrated circuit, interaction between magnet and coils with Simulink. This work optimizes the parameters of the design according to the simulation, including the size of magnet, coils, materials, etc.. The induced voltage and power output have been discussed under different driving conditions, taking account of various vehicle speeds and loads. Eventually, this work sets up the test bench and conducts the experiment to verify the simulation result. The simulation result shows maximum induced voltage of 7 V, load power of 6.8 mW. The experimental equivalent induced voltage is 2 V under motor speed of 160 r/min, which is consistent to the simulation result.