UPS power supplies can be divided into three types according to their working principles: backup type, online type, and online interactive type. UPS is generally divided into two categories in terms of structure: DC UPS (DC-UPS) and AC UPS (AC-UPS). In terms of backup time, UPS is divided into two types: standard type and long-term type without battery.
According to their working principles : UPS power supplies can be divided into three types: backup type, online type and online interactive type.
(1) Backup UPS
Normally, the battery is in the charging state. When the power is off, the inverter switches to the working state urgently, converting 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 is not required. 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 cannot be interrupted. However, in fact, this switching time is very short, generally between 2 and 10 milliseconds, and the computer’s own switching power supply should be able to maintain about 10 milliseconds when the power is off, so personal computer systems generally do 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, and its price is also relatively low. For computer applications that are not too critical, such as individual home users, a low-power backup UPS can be equipped.
(2) Online UPS
This type of UPS keeps its inverter in working state all the time. 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 the online UPS under power supply conditions is to stabilize voltage and prevent radio interference; when there is a power outage, the backup DC power supply (battery pack) is used to power the inverter. Since the inverter is always working, there is no problem of switching time, which is suitable for occasions with strict requirements on power supply. A major advantage of the online UPS is that the power supply lasts for a long time, generally for several hours, and sometimes 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 obviously much 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 mains power is normal, the UPS inverter is in reverse working (i.e., rectification working state) to charge the battery pack; when the mains power is abnormal, the inverter immediately switches to the inverter working state to convert the battery pack power into AC output, so the online interactive UPS also has conversion time. Compared with the backup UPS, the online interactive UPS has stronger protection function, the inverter output voltage waveform is better, generally a sine wave, and its biggest advantage is that it has strong software functions, which can easily access the Internet for remote control and intelligent management of UPS. It can automatically detect whether the external input voltage is within the normal range. If there is a deviation, the voltage can be stepped up or down by the voltage stabilizing circuit to provide a relatively stable sine wave output voltage. Moreover, it can communicate with the computer through a data interface (such as RS-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 supply quality of online UPS, but its frequency stabilization characteristics are not very ideal and is not suitable for long-delay UPS power supply.
According to its structure: UPS is generally divided into two categories: DC UPS (DC-UPS) and AC UPS (AC-UPS).
(1) DC UPS
The DC uninterruptible power supply consists of two basic units: rectifier and battery.
Its working process is: when the mains is normal, the current supplies power to the load through the rectifier, and the rectifier charges the battery at the same time. The current path is 1st mains-rectifier-load, 2nd mains-rectifier-battery. When the mains or rectifier fails, the control circuit automatically switches to make the battery supply power to the load, and the current flows from battery to load.
(2) AC UPS
The AC UPS power supply consists of three basic units: rectifier, battery and inverter.
Its working process is: when the mains is normal, the current supplies power to the load through the rectifier and inverter, and the rectifier charges the battery at the same time. The current path is 1: mains – rectifier – inverter – load, 2: mains – rectifier – battery. When the mains fails or the rectifier fails, the control circuit automatically switches to allow the battery to supply power to the load, and the current flows from battery – inverter – load.
According to the backup time: UPS is divided into standard type and long-term type
Generally speaking, standard machines have built-in battery packs that can maintain power supply for a short period of time (usually no more than 25 minutes) after a power outage. Long-lasting machines do not have built-in batteries, but have added chargers. Users can connect multiple battery packs according to their needs to extend the power supply time. Manufacturers will increase the charger capacity or install parallel chargers when designing.
Other categories
In addition, there are some other simple classifications of UPS, such as rotary UPS and static UPS based on the composition principle; commercial UPS and industrial UPS based on the application field; single-phase UPS and three-phase UPS based on the number of phases of the output voltage; large-capacity UPS (greater than 100KVA), medium-capacity UPS (10-100 KVA) and small-capacity UPS (less than 10 KVA) based on capacity.