Working principle of online interactive UPS

When the mains power is normal, the online interactive UPS directly supplies power to the load from the mains power. When the mains power is low or high, the output is stabilized by the UPS internal voltage stabilization circuit. When the mains power is abnormal or there is a power outage, it is switched to battery inverter power supply through the conversion switch. Its inverter and charger are combined into one, and the output is switched through the tap jump of the transformer to achieve segmented voltage stabilization.

Advantages of online UPS

High reliability: It combines the advantages of high efficiency of backup UPS and high power supply quality of online UPS.

High efficiency: When the mains power is normal, the electric energy is directly transmitted from the input end to the output end, and the inverter is only put into use when the mains power fails, which is highly efficient.

Reasonable voltage regulation: It has the function of automatic voltage regulation (AVR). When the mains voltage fluctuates, it can correct the abnormal voltage by adjusting the transformer tap to keep the output voltage within a certain range, reduce the frequency of battery use, and extend the battery life.

Reduce power consumption: The energy consumption is relatively low, which can effectively reduce the energy cost of the enterprise and save energy and reduce emissions.

Disadvantages

Power limit: It is usually not suitable for high-power occasions exceeding 5kVA.
Cannot prevent all forms of power violations: Some high-frequency noise, spikes and other interferences in the mains cannot be completely eliminated like online UPS.
No power factor correction and frequency regulation: It does not have power factor correction and frequency regulation functions.

Frequent use of batteries in extreme voltage distortion areas: If the mains voltage often fluctuates or distorts greatly, the online interactive UPS may need to frequently enable the battery to maintain the stability of the output voltage, which will accelerate the aging of the battery and shorten the battery life.

Online UPS (double conversion UPS)

Working principle

Using the "double conversion" method, the input AC power is first converted to DC by the rectifier to charge the battery, and then the DC power is converted back to AC by the inverter to supply the load. Regardless of whether the mains power is normal, the inverter is always in working condition.

Advantages

High power quality: It can provide high-quality and stable sine wave power with high voltage stabilization accuracy. The voltage stabilization accuracy is usually ±2%-3%. It can effectively eliminate interference such as harmonics, spikes, surges, etc. in the mains power. It is suitable for precision instruments, medical equipment, data centers and other places with extremely high requirements for power quality.

No switching time: There is no switching time problem. When the mains power is off, its automatic switching time is zero, which can ensure that the load equipment is not affected at the moment of the mains power outage, and achieve true seamless switching.

Disadvantages

High energy consumption: Since it is always in working state, it needs to charge the battery and maintain the operation of the inverter at the same time, so the energy consumption is relatively high, and the heat generation is also high. A good heat dissipation system is required to ensure the normal operation of the equipment, which also increases the operating cost to a certain extent.
High cost: The manufacturing cost of the equipment is relatively high. At the same time, due to the high energy consumption, the long-term operating cost is also relatively high.

Offline UPS (backup UPS)

Working principle

Usually, the mains power directly supplies power to the load. When the mains power is abnormal, it switches to battery power supply mode, and the inverter converts the DC power of the battery into AC power to supply the load.

Advantages

High efficiency: When the mains power is normal, it is directly powered by the mains power, with high efficiency.

Low cost: Simple structure, relatively low cost, suitable for ordinary office equipment, home computers, etc. that do not require high power quality and can withstand short power outages.

Disadvantages

Short switching time but interruption risk: There is a switching time, generally between 2 and 10 milliseconds, which may have a significant interruption effect on some equipment that is sensitive to power outages.

Low power quality guarantee: Only when the mains power is abnormal, it is powered by the inverter, the power quality is relatively poor, and the interference filtering effect on the mains power is limited. It is mainly used to protect the load from power outages.

Online interactive UPS vs online/offline UPS comparison summary

Online interactive UPS combines the advantages of backup UPS and online UPS, with high efficiency and good power supply quality. It is suitable for occasions that are more sensitive to cost and have certain requirements for power supply quality, such as ordinary corporate office environments, schools, small server rooms, etc.

Online UPS (double conversion UPS) provides the highest power quality guarantee and is suitable for critical places with extremely high requirements for power quality and no risk of power outages, such as large data centers, intensive care units in hospitals, and trading systems in financial institutions, but its energy consumption and cost are relatively high.

Offline UPS (backup UPS) has low cost and high efficiency, but has low power quality guarantee and switching time. It is suitable for ordinary office equipment and home computers that do not require high power quality and can withstand short power outages.