Lab 5 - Introduction

Uninterruptible Power Supply (UPS) systems are critical in providing reliable power in applications where uninterrupted power is essential, such as data centers, medical facilities, and industrial processes. A UPS system ensures continuous power supply during utility power interruptions by switching seamlessly to battery power. As shown in Figure 1, a typical UPS system consists of a rectifier, battery, inverter, and static switch, which work together to maintain power delivery to the load. The rectifier converts AC power to DC, charging the battery and supplying the inverter. The inverter then converts the DC back to AC to power the load.

Figure 1: Single line diagram of a UPS system.

UPS systems utilize various power electronic converters and control strategies to achieve high efficiency and reliability. Pulse-width modulation (PWM) is used in the rectifier and inverter stages to control the power flow and maintain a stable output voltage and frequency. In Lab 3, students studied the operation of two-quadrant DC-DC converters for battery charging and discharging, gaining insight into the control and simulation of these converters using HYPERSIM and Dashboards. Lab 4 introduced the modeling and simulation of an IGBT rectifier-inverter system, focusing on its steady-state operation as a PWM rectifier and output inverter in a UPS.

Building on this knowledge, Lab 5 will delve into the comprehensive study of a UPS system. Students will model, simulate, and analyze the performance of the UPS, exploring its ability to provide continuous power during interruptions. Through hands-on experience with HYPERSIM and Dashboards, students will gain a deeper understanding of the UPS's seamless transition between battery modes and the steady-state operation of the voltage source converter.