A typical UPS system block diagram is shown in Figure 1. Its basic structure is a set of rectifier and charger that converts AC mains power into DC power, and an inverter that converts DC power back to ac. the battery stores energy and maintains at a normal charging voltage when the AC power supply is normal. Once the mains power supply is interrupted, the battery supplies power to the inverter immediately to ensure the UPS power supply ACDischarge voltage.The following several diagrams show various working conditions of UPS (taking online UPS power supply as an example).
(1) As shown in Figure 2, the thick line depicts the direction of power supply energy when the utility power supply is within the scope allowed by UPS.
(2) When the main power supply fails, i.e. the mains power is cut off, the power supply will be supplied by the inverter instantaneously, as shown in Fig. 3.
(3) When the main power supply is turned on directly, as shown in Fig.
(1) A single UPS power supply can supply all loads. The connection diagram is shown in the schematic diagram of the system, and the connection method is relatively simple.
(2) In this way, two or more ups are connected in parallel, as shown in the figure.
(3) The total capacity of two or more UPS power supplies is more than the total load capacity, but the capacity of the system must be more than the total load capacity. When any one UPS power supply fails, the rest can still supply all loads, as shown in Figure 6.This connection is called parallel connection with backup.
(4) When the whole UPS power supply system fails, the utility will disconnect the UPS power supply and connect the load directly without affecting the maintenance of the UPS power supply system. The circuit design is shown in Fig. 7.
When there is no fault in the UPS power system, the maintenance switch is opened, and the input switch and output switch are closed; when the UPS power supply system fails, the maintenance switch is closed, and the input switch and output switch are opened.In this way, the normal operation of power load is ensured, and the on-line maintenance of UPS power system failure is not affected.