3D Printed Coils For Wireless Power Transfer

Wireless power transfer(WPT)technology has been gaining increasing popularity in recent,but most of the coils for the wireless power transfer(WPT)system are planar(2D)coils,2D coils limit the application of the WPT system in many electrical products with 3D freeform shapes.The recent development of 3D printed electronics offers a new way of designing and fabricating WPT systems,especially for the transmitter and receiver coils.3D printed electronics technology provides an extra dimension in designing and prototyping coils.It is possible to change the 2D coils to 3D coils,using 3D coils,a large area can be utilized for WPT,and a shorter distance between the transmitter and the receiver coils can be achieved,both contribute to a more effective and efficiently WPT system.In this dissertation,the author proposed a new method to design the 3D coils for the freeform surface;a mathematical model to calculate the parameters of/between the 3D coils;a new way to control the printing quality of the conductive traces and an optimization approach for the 3D printed coils.The main work of the dissertation can be concluded as:(1)An exploration of the 3D printed coils for wireless power transfer and a new design method based on the Non-uniform rational B-spline(NURBS)theory to design the 3D coils for the products with arbitrary 3D freeform shapes is proposed in this program as well.Based on the circular spiral and rectangular spiral patterns,3D receiver and transmitter coils can be generated on an arbitrarily selected region of a product and its offset by mapping,respectively.(2)Based on NURBS theory and Maxwell equations,a new mathematical model is derived to calculate the self-inductance and quality factor of the 3D coils,mutualinductance and coupling factor between the 3D coils in WPT system,compared with the simulation results from ANSYS? Maxwell? software and experiments,the mean absolute errors of our calculation results is lower than 4.5%,but the calculation speed is 30 times faster.(3)This dissertation proposed a new method to control the printing quality of the 3D printed silver traces in arbitrary shapes.By introducing a rotary platform on the base of the printer,we rebuild a “3+1” printer with four-axis,the 3D printing model was divided into several subparts according to the maximum printing angle,and the printing direction of every subpart can be adjusted to minimize the errors introduced by large inclination angles regarding different segments of the conductive trace.In our experiments,the average width of the conductive traces decreased from 1.7mm to 0.7mm,and the designed width of the conductive traces is 0.6mm.(4)Proposed an optimization approach for 3D printed coils using the genetic algorithm(GA).By the optimal strategy,the 3D transmitter and receiver coils meeting the objective function were generated on the transmitter and receiver mesh,in the next step,the receiver/transmitter coils were further optimized according to the fixed transmitter/receiver coils from the previous step.The experiments verify the optimization approach,the average resistance of the 3D coils decreased by 31.8%,the inductance power increased from 2W to 5W,and the power transfer efficiency of the system increased by 127%.(5)This program successful verified the possibility of using 3D printed coils for WPT in product design,the author redesigned,optimized and fabricated the electric toothbrush with 3D WPT system and printed a prototype using the Voxel8 printer,the receiver coil is embedded in the shell of the toothbrush,and the transmitter coil is embedded in the shell of the charger.It can be concluded that the proposed design,optimization,and fabrication approaches are feasible and promising for the 3D coils in the WPT system.