Optimal Design and Verification of Stacking-Hole in Transformer Core Based on Analysis of Magnetic-Fluid-Thermal Coupling

The loss and local temperature of the transformer core increases due to the stacking hole. To minimize the impact of the hole, a novel shape of the hole is designed and proposed in this paper. The finite element method and the experimental method are used to verify the optimization effect of the proposed novel hole. Based on the finite element method, the model of the core with the hole is established to simulate and calculate the core loss of the transformer under no-load condition. Subsequently, the loss as heat source maps into the thermal field to establish the magnetic-thermal-fluid coupling model. Considering the dependence of temperature on material properties, the convective heat transfer process is simulated and the temperature rise is calculated. The impacts of the traditional hole and novel hole on the transformer performance are compared and analyzed. Based on the experimental method, the loss and local temperature rise caused by the traditional hole and novel hole are quantitatively measured and compared. The simulation and experimental results show that, compared to the core without the holes, the loss is increased by 10-15% due to the traditional holes, the loss caused by the novel holes increases by 3-6% and the maximum optimization of the loss is up to 11%. The core with novel holes achieves an excellent performance which is superior to the core with current holes.