Why is Active PFC mandatory for power regenerators / conditioners for audio equipment?
Hi kanwar, would one need pf correction for regenerators ? I thought they maybe needs only for active conditioners.
A power regenerator produces high quality sinewave either from linear means or switching pwm stages. Both cases work as an amplifier fed with constant frequency sinewave and the output is fed to audio equipment as mains voltage source regenerated by the circuitry. But in doing so regenerators put a high peak charging current load on actual mains line voltage. This is where the problem actually arises.
The mains from wall socket is rectified directly or thru isolation transformer if present and then unregulated DC voltage is obtained with smotthing bank of capacitors. As long as the power draw is less than 100W, the harmonic content in the mains line is under acceptable levels, but when it increases the charging current required by capacitors put a lot of load at the PEAK CYCLES of mains sinewave from your wall socket. This give rise to situation called premature clipping of mains waveform. Every time the equipment such as power amplifier draw current from regenerator, the regenerator draws a high surge current from the line only at peak of waveform in order to retain the charge in capacitors. This way the output of regenerator is pure sinewave
BUT THE INPUT CURRENT FROM THE MAINS SOCKET IS IN FORM OF PEAK PULSES which not only increases disturbances on the line but also puts a burden on mains current draw with associated EMI on the route of your mains cable from power inlet socket to rengenerator input. This also increases electricity bills, reduced efficiency of power utilization.
With active power factor correction you have following advantages:
1. The input current draw from wall socket will follow the same shape of voltage waveform which is sinewave in nature, thus utilizes entire cycle of voltage waveform to charge the capacitors of DC bus voltage.
2. The harmonic generation is 10X times less than what you have without PFC. Less EMI generated, less noisy environment in surroundings.
3. The regulation achieved for DC bus voltage would further stabilize the output waveform because the PFC is designed to work from 90VAC to 265VAC, so any type of fluctuation on mains line will not effect the operation. Plus universal mains plug n play capability.
4. Due to high power factor obtained the power utilization would be very high and less mains consumption hence low electricity bills. No wastage thru high current drawing surges.
5. Since the input of PFC is current fed you get inherent protection from spikes, surges, noises, fluctuations, contaminated, clipped mains line. Imagine a welding set/water pumps operating in near by shop/home and interacting with your equipment. With PFC you will be completely immune from such things.
6. European union energy commission emphasis PFC on equipments whose power draw exceeds 75W continuous. Which means in near future this would be implemented in Asia also. Having a PFC is greener option.
The regenerators without PFC no doubt gives cleaner output but contaminates the line input current and generates harmonics.
Industrial 3-phase world already made the use of PFC as mandatory norm in order to control line current contamination. Now the turn is for home public line distribution.
See the attached photo.
