The UPS power system consists of four parts: rectification, energy storage, conversion, and switch control. The voltage stabilization function of its system is usually completed by rectifiers, which use controllable silicon or high-frequency switch rectifiers. They have the function of controlling the output amplitude according to changes in external power, so that when the external power changes (which should meet the system requirements), the output amplitude of the rectified voltage remains basically unchanged. The purification function is completed by the energy storage battery. Due to the inability of the rectifier to eliminate instantaneous pulse interference, there are still interference pulses in the rectified voltage. In addition to the function of storing DC energy, energy storage batteries are like connecting a large capacitor to a rectifier, and the equivalent capacitance of the energy storage battery is directly proportional to its capacity. Due to the fact that the voltage across the capacitor cannot suddenly change, the smoothing characteristics of the capacitor for pulses are utilized to eliminate pulse interference, which serves as a purification function, also known as shielding against interference. The frequency stability is achieved by the transformer, and the frequency stability depends on the stability of the oscillation frequency of the transformer. For the convenience of daily operation and maintenance of the UPS power system, system operation switches, automatic bypass switches after host self check faults, and maintenance bypass switches have been designed for switch control.
When the grid voltage is working normally, supply power to the load as shown, and at the same time, charge the energy storage battery; When there is a sudden power outage, the UPS power supply starts working, and the energy storage battery worker provides the required power to the load to maintain normal production (as shown in bold black →); When the load is severely overloaded due to production needs, the grid voltage is rectified to directly supply power to the load (as shown in the dashed line).
The UPS power system is mainly divided into two parts, the host and the energy storage battery. The rated output power depends on the host part and is related to the nature of the load, as UPS power supplies have different driving capabilities for loads of different performance. Usually, the load power should meet 70% of the rated power of the UPS power supply. The selection of energy storage battery capacity mainly depends on the length of its backup time after the load power is determined. This time varies depending on the situation of each enterprise and is mainly determined by the connection time of the backup power source, usually ranging from a few minutes to several hours. Due to production needs, the small and medium-sized bar production line of Laigang does not allow power outages. Therefore, the UPS power supply system can start supplying power on its own after detecting a voltage interruption in the power grid. As the energy storage battery slowly discharges, the capacity of the energy storage battery will gradually decrease over time. Considering that the capacity of the energy storage battery will decrease to 50% at the end of its life and leave a certain margin, the working time of our UPS power supply system is 2 hours when the energy storage battery is at full capacity and 1 hour at half capacity.