Enhancement of electric field uniformity using 3-phase circular electrodes in RF heating applications

This paper introduces a novel electrode structure designed to enhance electric field uniformity in radio frequency heating applications, such as food processing. The proposed 3-phase circular electrode structure, the top electrode, consists of innermost, middle, and outermost electrodes, with each electrode supplied with a voltage of a different phase. By utilizing relative phase differences between the top electrodes, the electric field distribution between the top and bottom electrodes can be effectively modified to apply a uniform electric field on the food sample. A 3D computational simulation model was used to analyze the electric field uniformity at an operating frequency of 13.56 MHz and compared it with conventional single-phase rectangular electrodes. Both simulations and experimental measurements were conducted at 16 points on a plane 1 mm above a ham sample to evaluate the electric field strength. The results showed that the 3-phase circular electrodes effectively concentrated the electric field at the sample's center while mitigating electric field strengths at the edges and corners. Consequently, electric field uniformity was significantly improved from 75.31% with conventional single-phase rectangular electrodes to 91.89% with the proposed 3-phase circular electrodes. This 3-phase circular electrode structure demonstrates promising potential for enhancing electric field uniformity in RF heating systems.