About equal parts Snake oil & bull faeces!
Power factor certainly is a real phenomena and, in some situations, it should be corrected for. But to correct for PF with a ridiculously complex circuit using ICs instead of a couple of passive components seems a little hard to justify.
Power factor certainly is a real phenomena and, in some situations, it should be corrected for. But to correct for PF with a ridiculously complex circuit using ICs instead of a couple of passive components seems a little hard to justify.
It is not the complexity what matters, it is what is the cost and other factors. PFC chips are not generally very expensive, as the application is quite cost sensitive.
Passive PFC implementation leads to very big and bulky passive components (which tend to be quite expensive), and result is not usually good enough to meet the requirements of harmonic currents (IEC61000-3-2). That is even more the case when power levels rise. Problem which is solved by PFC is not reactive linear load phase shift, but the insanely high current peak which flattens out the sinusoidal waveform due to finite grid impedance. Using a PFC makes peak current much lower as load is made look like a resistor.
Regards,
Janne
Umm, complexity = cost. At a lot of companies in my area, circuit design costs upwards of $100 / hr. So you see, the cost of passive components quickly becomes a non-issue compared to the labor cost. You also ignored the cost of assembly, which increases with complexity. And since when were large and bulky passive components required? There are 20 F or larger "super" caps that take up less room than that active PFC circuit.
The whole concept of PFC is really no different than impedance matching in RF. We don't have any of these problems with harmonic currents with an RF source driving an impedance matched diode. In RF, there are well defined equations, based on physics, governing impedance matching and filtering. But when it comes to 60 Hz AC, all I see is a lot of hype and little to no science.
But when it comes to 60 Hz AC, all I see is a lot of hype and little to no science.
I see you like to call people names without recognizing that what you see in industry is often a result of marketing and political environments, with very little scientific reason. Lead free solder and ethanol are a few examples.
So let's talk about PFC. The power factor is the ratio of dissipated power to apparent power. With a resistive load, power factor is unity. Whenever there is a reactive load, the power factor is less than unity. The purpose of power factor correction is to maximize power delivered to the load. Power factor correction is performed by making the load look purely resistive. This is called an impedance transformation.
We can transform the impedance with active circuitry or passive. In the RF world, active impedance matching is generally reserved for use on ICs where space is a consideration. A lot of common household appliances look like an inductive load, so to compensate, we add a shunt capacitance at the input. This maximizes the power transfer to your appliance. Instead of a shunt capacitance, yes, I could waste an entire circuit board full of active components. But I would need to see the math to be convinced that it actually works any better. In fact, it wouldn't surprise me in the least if circuits with active power factor correction were just as inefficient as circuits without any power factor correction, because of the additional power draw.
We can transform the impedance with active circuitry or passive. In the RF world, active impedance matching is generally reserved for use on ICs where space is a consideration. A lot of common household appliances look like an inductive load, so to compensate, we add a shunt capacitance at the input. This maximizes the power transfer to your appliance. Instead of a shunt capacitance, yes, I could waste an entire circuit board full of active components. But I would need to see the math to be convinced that it actually works any better. In fact, it wouldn't surprise me in the least if circuits with active power factor correction were just as inefficient as circuits without any power factor correction, because of the additional power draw.
What you suggest has been used by power engineering people for several decades at least. Reactive power compensation by adding compensation capacitors is not a new thing, and synchronous motor can be used as a dynamic compensator which can act as an inductor or capacitor as required. But, matter of PFC is also to reduce the harmonic currents (or current distortion), i.e. to make the waveform more sinusoidal. As an example what it means as it seems not to be obvious, what kind of passive component could turn this example into linear load (seen by voltage source V1) as effectively as an active PFC:
DC load is 200 watts, but loading from the voltage source is about 420 VA, so power factor is about 0.47. How would you compensate that?
Regards,
Janne
Shunt capacitor will do nothing about the peaks. What you use is a LC tank in series with the one line, tuned to resonate ( but with low Q of course) at 3 times the mains frequency. This does a pretty good job of presenting a linear looking load to the supply, while increasing the conduction time of the diode considerably, lowering the power dissipated there.
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If your electricity is dirty, you wash it! Right.
electrons are extremely dirty ! they come from a power plant , travel through dirty lines and transformers , go through the washing machine motor of your neighbour , the dishwasher and other electrical appliances before they eventually run through your stuff. they are like money : the dirtiest thing on the planet and who knows where they have been before... bah ! they could be carrying all kinds of cooties !
besides : why do we need to pay for electricity ? for every electron that comes in our house we deliver one back to power plant. we don't use them.
the powerplants should be paying us since we give the electrons passage through our home wiring and equipment thus lowering the overall resistance the powerplant sees ! the less resistance there is in the network the fewer the losses are ....
this is all a big hoax.
Thanks for the laugh!
Laugh ? I'm dead serious !
Imagine having electrons that have gone through the neighbours washing machine motor at 1500rpm flow through your "double solid silver foil wrapped oxygen-free copper interconnects with 15 micron gold plated end connectors" And then they hit your hand wound counter earth-spin powertransformer of your audio installation ! you will hear that in the speakers ! these dirty electrons may permanently poison your primary transformer and damage your audiophile setup !
Luckily you can buy little handpainted rosewood veneer MDF 'pucks' to put under the legs of the amplifier. They will compensate for the neighbours washing machine motor induced vibration of the electrons ... only 9.999$ a piece. To get even better performance you can stack mulitple on top of each other. (*)
We also have pucks for microwave oven , dishwasher , dryer and many other household appliances. If you suspect an appliance we can custom make new pucks. Development cost is 15000$ and you will need to ship us the suspect appliance.
we recommend buying a set for every appliance and making a stack out of those (*)
(*) not responsable for toppling amplifiers if you would stack a whole bunch of them under each leg
i'm secretly hoping someone will ship me some appliances and a fat wad of money... i got some scrap wood to get rid of and i could use a new dishwasher