Design and Electro-Thermal Optimization of Power Distribution Units for High-Temperature Industrial Fast Hole Drilling Systems

An important consideration in fast-hole drilling electrical discharge machining (FHD-EDM) systems is the reliable power delivery under high current and high temperature operating conditions. The developed mathematical model considers the electrical conductivity, the temperature-dependent electrical resistivity, the contact resistance, the Joule heating, the convection, the radiation and the transient heat transfer to analyze the coupled electrical and thermal behavior of the system. The model predicts voltage drop, current density, electrical resistance, power loss, temperature rise, heat flux and thermal hotspot development under various operating conditions. The results show that increasing current and contact resistance lead to higher electrical losses and maximum temperature, while improved cooling decreases both electrical losses and maximum temperature. These results emphasize the influence of electrical loading, contact resistance and cooling conditions on the electro-thermal response of the FHD-EDM power distribution unit. Low contact resistance, moderate conductor thickness and improved cooling was determined as design conditions based on Taguchi analysis. A surrogate-assisted multi-objective optimisation framework based on Gaussian Process Regression (GPR) and the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) is also employed to investigate the trade-offs between maximum temperature, power loss, and voltage drop. The proposed framework provides a systematic approach for analysing the coupled electro-thermal behaviour of the PDU and evaluating design trade-offs within the investigated operating conditions. In conclusion, the proposed scheme can be considered as an efficient solution for optimizing the PDU efficiency, thermal stability, operational reliability, and component lifespan, for high power EDM systems.