The line-interactive UPS inverter does not output power to the load under normal conditions of the main AC mains and is in a hot backup state, which is the fundamental difference between it and the backup UPS. The inverter can transmit power in both directions, so the inverter can charge the battery at the same time, which increases the charging power capacity of the UPS when the mains power is normal and reduces the conversion time when the mains power fails.
Input switch: When the mains power is normal, the switch is turned on; when the mains power fails, the switch is automatically turned off to prevent the inverter from feeding back to the grid.
pure sine wave line-interactive UPS
Automatic voltage stabilization: When there is a mains power supply, it can roughly stabilize the voltage and absorb some grid interference. The voltage stabilization method is roughly the same as the backup type. Relays are often used to change the transformer tapping method. When the input voltage is high, the transformer will step down, and when the input voltage is low, the transformer will step up, and the output voltage regulation accuracy is 5%~10%.
Inverter: This inverter has a two-way conversion function. When there is the mains power supply, it is an AC/DC rectifier to charge the battery; when the mains power fails, it is converted to a DC/AC inverter, powered by the battery, and UOS continues to supply power to the load. The output voltage waveform can also be a quasi-sine wave, but due to the large output power, the load may have equipment that requires the input voltage to be a sine wave, so the inverter output voltage of line-interactive UPS is mostly sine wave.
When the electricity is normal, the work efficiency is extremely high, reaching 98 or more. The input power factor and input current harmonic components depend on the nature of the load, and it does not add harmonic interference to the power grid.
The output capacity is strong when the mains power is normal, and it is suitable for various impedance loads. There are no strict restrictions on the load current crest factor, surge factor, output power factor, and overload capacity.
The output voltage accuracy and stability are poor, but it can meet the power supply requirements of general loads. The inverter is directly connected to the UPS output terminal and is in a hot backup state, which has a certain inhibitory effect on the spike fluctuation of the input voltage. The circuit is simple, low cost, and high reliability. The converter also has a charging function, and its charging ability is stronger than that of the backup type.
uninterruptible power supply manufacturers: industrial computer power supply
Because the input switch has an off time, the UPS output still has a conversion time, but it is shorter than the backup type, generally 4~6ms. If an inductance is connected in series between the input switch and the automatic voltage regulator, when the mains power fails, the inverter can supply power to the load immediately, which can avoid the short circuit caused by the inverter feedback to the grid when the input switch is disconnected. Danger (inverter reverse protection function), while reducing the line-interactive conversion time to zero, and increasing the anti-interference ability, but this will reduce the input power factor.
Backup and line-interactive UPS do not have the problem of setting up a static bypass switch separately. For double conversion (online) UPS, because the output capacity of the inverter is limited, when the load current is overloaded or the inverter fails, the UPS will switch from the mains inverter state to the static bypass and the mains directly supply power to the load. Back-up and line-interactive UPS, when the mains power is normal, the inverter will not work or work without load, and will not damage the inverter when the mains power is normal. The voltage stabilization link of these two UPSs is simpler and more reliable than double conversion ( The static bypass of the online) UPS has high reliability and strong resistance to overload and impact, which is equivalent to an online bypass structure.