UPS, as an important peripheral of the computer, is very important in protecting computer data, ensuring the stability of the power grid voltage and frequency, improving the quality of the power grid, and preventing the harm caused by instantaneous power failure and accidental power failure to users.
    UPS has developed from the rotary generator of the 1960s to today's static fully electronic circuit with intelligence, and continues to develop. At present, UPS generally refers to static UPS, which can be divided into three categories according to its working mode: backup, online interactive and online.
    When the mains is normal, the backup UPS directly supplies power from the mains to the load. When the mains exceeds the working range or the power is cut off, the backup UPS switches to battery inverter power supply through the switch. Its characteristics are: simple structure, small size, low cost, but the input voltage range is narrow, the output voltage stability accuracy is poor, there is a switching time, and the output waveform is generally square wave.
    When the mains is normal, the online interactive UPS directly supplies power to the load from the mains. When the mains is low or high, the UPS supplies power through the voltage regulator line. When the mains is abnormal or there is a power outage, the UPS switches to battery inverter power supply through the switch. It is characterized by a wide input voltage range, low noise, small volume and so on, but there is also a switching time.
    When the mains is normal, the mains provides DC voltage for the inverter to work, and the inverter provides AC power for the load. When the mains is abnormal, the battery provides energy for the inverter. The inverter always works to ensure uninterrupted output. It is characterized by an extremely wide input voltage range, no switching time and high output voltage stability accuracy, which is especially suitable for occasions with high power requirements, but the cost is high. At present, almost all UPS with a power greater than 3KVA are online UPS.
    According to the output capacity, the UPS is divided into small capacity less than 3KVA, small and medium capacity 3KVA~10KVA, and large capacity more than 10KVA. The UPS can be divided into three types according to the input/output mode: single-phase input/single-phase output, three-phase input/single-phase output, and three-phase input/three-phase output. Single-phase power is a power supply system composed of a live wire, a neutral wire and a ground wire. Three-phase power is a power supply system composed of three live lines, one neutral line and one ground line, in which the voltage between the two live lines (that is, the line voltage) is 380V, and the voltage between the live line and the neutral line (that is, the phase voltage) is 220V. For users, the three-phase power supply of its mains power distribution and load distribution is easy, and each phase bears a part of the load current, so medium and high-power UPS use three-phase input/single-phase output or three-phase input/three-phase output power supply mode.
    Intelligent UPS is a major development trend of UPS today, with the application of UPS in the network system, the network manager emphasizes the whole network system as the protection object, hoping that the whole network system can continue to work without interruption when the power supply system fails. Therefore, the UPS internal configuration of microprocessor to make it intelligent is a new trend of UPS, UPS internal hardware and software combination, greatly improve the function of UPS, you can monitor the UPS operating status, such as: UPS output voltage frequency, grid voltage frequency, battery status and fault records. It can also detect the battery through software, automatically discharge and charge, and remotely switch the machine. The network manager can analyze the power supply quality according to the information and take corresponding measures according to the actual situation. When the UPS detects that the power grid is interrupted, it automatically switches to the battery power supply. When the battery power supply is insufficient, the UPS immediately notifies the server to prepare for shutdown and shuts down before the battery runs out. The intelligent UPS communicates with the computer through the interface, so that the network administrator can monitor the UPS, so the function of its management software is extremely important.