How Does An Uninterruptible Power Supply Work?

System composition
The block diagram of a typical UPS system is shown in Figure 1. Its basic structure is a set of rectifiers and chargers that convert AC power into DC power, and an inverter that converts DC power into AC power. The battery stores energy and maintains a normal charging voltage when the AC power is normally supplied. Once the AC power supply is interrupted, the battery immediately supplies power to the inverter to ensure the AC output voltage of the UPS power supply. The following diagrams illustrate various working conditions of the UPS (taking the online UPS power supply as an example).
(1) When the AC power is normally supplied within the range allowed by the UPS, as shown in Figure 2, the thick line depicts the flow of power energy.
(2) When the main power supply fails, that is, the AC power is cut off, the power supply will instantly switch to the inverter to provide energy, as shown in Figure 3.
(3) When the load is too large or the inverter in the power supply fails, the UPS will open the bypass and supply power directly from the main power supply, as shown in Figure 4.
Connection method
(1) A single UPS power supply can supply all loads. The connection diagram is as shown in the system schematic diagram. The connection method is relatively simple.
(2) The total load power needs to be supplied by two or more UPS power supplies, as shown in Figure 5. This connection method is called parallel without backup.
(3) The total capacity of two or more UPS power supplies is greater than the total load capacity, but the system must have one more UPS power supply capacity than the total load capacity. When any UPS power supply fails, the remaining ones can still supply all loads, as shown in Figure 6. This connection method is called parallel with backup.
(4) After the entire UPS power system fails, the mains disconnects the UPS power supply and directly connects the load without affecting the maintenance of the UPS power system.
When Uninterruptible Power Supply(UPS) is fault-free, the maintenance switch is opened, and the input switch and output switch are closed; when the UPS power system fails, the maintenance switch is closed, and the input switch and output switch are opened. In this way, the normal operation of the power load is guaranteed without affecting the online maintenance of the UPS power system failure.