Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
A thermal-analysis guided redesigning of uninterruptible power supply for energy storage applications
Submission Author:
Rafael Guariza , SP , Brazil
Co-Authors:
Rafael Guariza, Michele Rodrigues Hempel Lima, Wellington Cássio Pinheiro, Felipe Ramos Braidotti
Presenter: Rafael Guariza
doi://10.26678/ABCM.COBEM2023.COB2023-1429
Abstract
In recent years, there has been a growing demand for decarbonizing the power system by incorporating renewable energy sources such as wind and solar power. However, these green energy sources are characterized by intermittent generation, which has brought energy storage to the forefront of attention. Uninterruptible power supply (UPS) systems, which rely heavily on power electronics and magnetic elements, have emerged as a key solution to address this issue. To ensure the reliability of these critical components and extend their lifespan, a design based on an effective and reliable thermal analysis is essential. Therefore, this study proposes a redesign of a commercial line-interactive sinusoidal UPS of 1400VA with an output RMS voltage of 115 V (60 Hz) based on a thermal analysis. The focus of the analysis is on key components such as the transformer, power transistors affixed to heat sinks, and a cooling unit. The first round of thermal analysis was conducted using Ansys Fluent simulation calibrated with experimental data obtained from a temperature analyzer and Type K thermocouples. The simulation results suggested internal layout changes such as rotating the transformer by 90°, replacing the core windings with aluminum, and increasing fan intake velocity, among others. A second round of simulations was performed, taking the layout changes into account. The results showed a marked decrease in temperature, as the novel configuration optimized airflow by enabling smoother, uninterrupted flow and increased turbulence while minimizing energy losses. Although this approach improved heat transfer between components and air by promoting turbulence and forced convection, at higher velocities, a sudden airflow deviation near the intake caused a temperature increase due to disrupted forced convection in the transistor region. Nonetheless, this study demonstrates how engineering design based on modeling and simulations increases product maturity, diminishes rework, and engineering hours. By improving UPS reliability, this work contributes to the development of a sustainable and decarbonized power system.
Keywords
uninterruptible power supply (UPS), Power Electronics, Thermal Analysis, Computational fluid dynamics (CFD), Simulation
