A Zero Current Switching Half-Bridge Power Supply for High Speed Drilling Electrical Discharge Machining

High speed drilling electrical discharge machining (HSDEDM) uses controlled electric sparks to erode the metal in a work-piece. Through the years, HSDEDM process has widely been used in high speed drilling and in manufacturing large aspect ratio holes for hard-to-machine material. The power supplies of HSDEDM providing high power applications can have different topologies. In this paper, a HSDEDM power supply prototype has been developed, utilizing the Zero Current Switching (ZCS) Pulsed Width Modulated (PWM) half-bridge topology with a minimal component count and inherent protection under short circuit conditions. This topology has an energy conservation feature and removes the need for output bulk capacitors and resistances. Energy used in the erosion process will be controlled by the switched IGBTs in the half- bridge network and be transferred to the gap between the tool and work-piece. The relative tool wear and machining speed of our proposed topology have been compared with that of a normal power supply with current limiting resistances.