Variable turn pitch coils design for heating performance enhancement of commercial induction cooker

This study aims to enhance heating performance of an induction cooker with convex bottom Chinese wok for commercial applications. Traditional single coil solution is first designed according to the wok shape. The theoretical closed-form expressions of the eddy currents in the wok are derived, and further verified by finite-element method (FEM) analysis. The results reveal the localised and uneven eddy currents distribution for the induction cooker with an evenly distributed single coil. Variable turn pitch (VTP) coils are then proposed to address the eddy currents distribution problem. Corresponding analytical equations are given to present the design process of the VTP coils. The resulting eddy currents distribution on the wok is validated to be improved by applying the VTP coils. The inductance characteristics of the proposed VTP coils are also studied by conducting FEM and physical measurements. Finally, a prototype of the proposed system is developed and has undergone comprehensive experiments. The experimental results validate the theoretical analysis, indicating that the heating performance of the induction cooker system would be remarkably enhanced by implementing the VTP coils.