High Efficiency Fragment Conversion Online-UPS
There are several types of online UPS topologies in the industry, double conversion, triple conversion etc which are popular for many years. But in the era demanding higher efficient energy saving products these power topologies are showing their limitations due to low efficiency and higher material cost.
Fragment Conversion Online-UPS is a new topology which replace the conventional double/triple conversion online UPS which achieves High Efficiency (> 97%), high Power Factor (0.99), low THD (< 3%), Tight output Regulation (±1%) and low cost. The power sections convert/process only a fragment power and achieve higher efficiency.
The Fragment Conversion UPS block diagram is shown in the figure 2. The main blocks are AC-AC bilateral PWM converter, Bilateral Inverter stage and Static Switch. When the AC Power is present the Inverter Section also act as a Harmonic Injection APFC and Charger.
Considering a 5% conversion loss, 5% of 22.7% = 1.1% of the full load. (22.7 × 5 / 100 = 1.1%)
In the block diagram, the inverter stage is directly connected to the output. When AC is present, the static switch will be switched on and the difference power will be processed to get constant voltage at the output. The inverter will act like a harmonic injection type APFC and at the same time it will charge the battery. The inverter will inject and extract the difference harmonics of the current waveform from / to the AC for getting the power factor close to unity and less THD.
When the AC fails, the static switch will switch off and the inverter will start working at the same point where the AC failed to continue the cycle without interruption and produce a pure sine wave at the output.
Since only the difference power is to be processed, the power handed by the components will be low. Hence higher efficient low power rating components are sufficient which will reduce the material cost.
By using Fragment Conversion topology we can achieve – Higher efficiency compared to existing methods, More energy saving and reduced carbon emissions.
The only disadvantage in this topology is – the output frequency will be the same as input frequency when the UPS is working in AC mode. But in double conversion type of UPS the output frequency can be changed, though this may not be essential in many applications.
P.A. Martin Xavier is Hardware Designer and Managing Partner, Martin’s Electronic Devices & Instruments
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