AC‑DC‑AC architecture of power frequency on-line UPS, through two thorough power form conversion+power frequency isolation+precise control, realizes the deep purification of commercial power, so that the load is powered by pure sine wave output by inverter in the whole process, and is completely isolated from power grid interference.
I. Core Architecture and Workflow
When the mains supply is normal (double conversion mode)
Commercial power → power frequency input transformer → rectifier (AC→DC) → DC bus → inverter (DC→AC) → output isolation transformer → load.
At the same time, the rectifier floats the battery pack and keeps it fully charged for standby.
The load is 100% powered by inverter, which is physically isolated from the mains.
When the mains supply is abnormal/interrupted (battery mode)
Battery pack → DC bus → inverter → output isolation transformer → load
0ms seamless switching, no load perception.
Second, the four key mechanisms of power deep purification
1. The first purification: rectification (AC → DC)-completely eliminate the interference of the commercial power.
Voltage stability: wide input range (e.g. 160–275 V/304–456 V), stable DC bus voltage after PWM rectification, completely smoothing the fluctuation, drop and surge of commercial power.
Harmonic and interference filtering: Convert AC containing harmonics, spikes and noises into smooth DC, where all AC interferences are completely removed.
Power factor correction (PFC): input PF≥0.99 and THDI < 5%, so as to reduce the pollution to the power grid.
Primary electrical isolation: the power frequency input transformer realizes the primary isolation between the power grid and the DC bus, blocking high-voltage surge and common-mode interference.
2. Second purification: inverter (DC → AC)-generating perfect sine wave.
Standard waveform output: the inverter regenerates the standard 50Hz sine wave from the pure DC bus, with THD≤1% (full load).
Precise control of voltage/frequency: the output voltage accuracy is 1% and the frequency accuracy is 0.5%, which is completely independent of the mains frequency.
Load adaptability: it can be mixed with resistive/capacitive/inductive load, and the output is not affected by load characteristics.
3. The third purification: output isolation transformer-ultimate isolation and anti-interference.
Complete electrical isolation: the load is completely isolated from the power grid and DC bus, blocking DC components, high-frequency noise and zero-ground voltage interference.
Zero-ground voltage suppression: the output zero-ground voltage is ≤2V, which meets the requirements of precision equipment.
Shock resistance and lightning protection: improve the ability of surge resistance, lightning protection and short circuit tolerance.
4. Full online power supply-completely get rid of the influence of mains electricity.
The load is always powered by the inverter, and any fluctuation, interruption and pollution of the commercial power can not affect the output.
Different from standby/online interaction, there is no "direct supply of mains electricity" link, and there is no dead angle for purification.
III. Purification Effect and Key Indicators
Voltage: stable 1%, no transient, surge and spike.
Frequency: accurate 0.5%, not affected by mains frequency drift.
Waveform: pure sine wave, THD≤1% (full load)
Isolation: the input and output are electrically isolated, and the zero ground voltage is ≤2V.
Anti-interference: completely filter out harmonics, noise and DC components.
summary
The dual conversion architecture of power frequency on-line UPS realizes the deep and thorough purification of the commercial power through two thorough conversions of AC‑DC‑AC+dual power frequency isolation+full-process inverter power supply, and provides "zero interference, zero interruption and high stability" power guarantee for key loads.
