Reduction of Inrush Current in a Shockwave Non-Thermal Food Processing System Using an Exponential Clock Pulse Generator

Abstract

Recently, shockwave food processing is drawing much attention as a low-cost non-thermal food process technique. In shockwave non-thermal food processing, underwater shockwaves are generated by a high voltage generator. Therefore, high inrush currents and high voltage stress on circuit components significantly reduce the reliability and life expectancy of the circuit. However, to the best of our knowledge, stress reduction techniques and their experimental verification have not been studied yet in the shockwave non-thermal food processing system. In this paper, we propose a stress reduction technique for the shockwave non-thermal food processing system and investigate the effectiveness of the proposed technique experimentally. To achieve high reliability and life expectancy, a new high voltage multiplier with an exponential clock pulse generator is proposed for the shockwave non-thermal food processing system. By slowing down the rate at which the capacitors charge in the high voltage multiplier, the exponential clock pulse generator significantly reduces the inrush current. Furthermore, to perform shockwave non-thermal food processing continuously at a lower voltage level, we present a new electrode with a reset mechanism for wire electric discharge (WED), where a square-shaped metal wire swings on a hinge in the proposed electrode. The proposed electrode enables not only shockwave generation at a lower voltage level but also continuous non-thermal food processing, because the square-shaped metal wire is not melted in the WED process. To confirm the validity of the proposed techniques, some experiments are performed regarding the laboratory prototype of the shockwave non-thermal food processing system. In the performed experiments, reduction of inrush currents and effective food processing are confirmed.