Classification Of Ups Uninterruptible Power Supply

According to its working principle, Uninterruptible Power Supply(UPS) can be divided into three types: backup type, online type and online interactive type.

(1) Backup UPS

The battery is normally charged. When a power outage occurs, the inverter switches to the working state to convert the DC power provided by the battery into a stable AC output. Therefore, the backup UPS is also called an offline UPS. The advantages of the backup UPS power supply are: high operating efficiency, low noise, and relatively cheap price. It is mainly suitable for occasions where the mains power fluctuation is not large and the power supply quality requirements are not high. It is more suitable for home use. However, this UPS has a switching time problem, so it is not suitable for use in critical places where power supply is not always interrupted. However, in fact, this switching time is very short, generally between 2 and 10 seconds, and the computer's own switching power supply should be able to maintain about 10 seconds when the power is off, so the personal computer system generally does not have problems due to this switching time. The backup UPS can generally only provide power for a few minutes to tens of minutes, mainly to give you time to back up data and finish the work at hand as soon as possible. Its price is also relatively low. For computer applications that are not too critical, such as personal home users, a low-power backup UPS can be used.

(2) Online UPS

This type of UPS keeps its inverter in working condition. It first converts external AC power into DC power through the circuit, and then converts DC power into high-quality sinusoidal AC power through a high-quality inverter to output to the computer. The main function of an online UPS under power supply conditions is to stabilize voltage and prevent radio interference: in the event of a power outage, a backup DC power supply (battery pack) is used to power the inverter. Since the inverter is always working, there is no switching time problem, and it is suitable for occasions with strict requirements on power supply. A major advantage of an online UPS over a backup UPS is that it provides long-lasting power, generally several hours, but also up to more than ten hours. Its main function is to allow you to work as usual in the event of a power outage. Obviously, due to its special function, the price is also significantly more expensive. This type of online UPS is more suitable for industries such as computers, transportation, banking, securities, communications, medical care, and industrial control, because computers in these fields generally do not allow power outages.

(3) Online interactive UPS

This is an intelligent UPS. The so-called online interactive UPS means that when the input power is normal, the UPS inverter is in reverse operation (i.e., rectification working state) to charge the battery pack; when the input power is abnormal, the inverter immediately switches to the inverter working state to convert the battery pack power into AC output. Therefore, the online interactive UPS also has conversion time. Compared with the backup UPS, the online interactive UPS has stronger protection function and the inverter output voltage waveform is better, generally a sine wave. Its biggest advantage is that it has strong software functions and can easily access the Internet for remote control and intelligent management of the UPS. It can automatically detect whether the external input voltage is within the normal range. If there is a deviation, the voltage can be increased or decreased by the voltage stabilization circuit to provide a relatively stable sine wave output voltage. Moreover, it can communicate with the computer through a data interface (such as the S-232 serial port). Through the monitoring software, users can directly monitor the power supply and UPS status from the computer screen, simplifying and facilitating management work, and improving the reliability of the computer system. This type of UPS combines the advantages of high efficiency of backup UPS and high power quality of online UPS, but its frequency stability performance is not very ideal and is not suitable for long-delay UPS power supply.