RickHaleParker wrote: ↑15 Jan 2018, 18:07 "First we see you have the unusual idea that power is not a quantity."
Is a fact power is a rate not a quantity This is fundamental, whip out your training manual and read the definition for power, not the equation, the definition. Or you can just google "Power Scientific Definition".
"then you darn well better know what you are talking about. Sorry to say, something is wrong here."
I know what I'm talking about and can back it up.
"Sorry to say, something is wrong here."
You spent time in the energy sector and engineering and you don't know power is a rate not a quantity ... that is whats wrong. People reading this are going to Google "Power Scientific Definition" and get the facts.
"I really cant see how you could have gotten that idea."
I did something different when I was in school, I got educated instead of just learning to pass a test.
"Second, the phrase "power conversion" is an accepted phrase"
Common mis-usage like Volts = Current * Resistance instead of Electromotive Force = Current * Resistance.
Electromotive Force, Current and Resistance are quantities. Volts, Amps and Ohms are units of measurements.
"where W is the energy. That's acceptable, but the P form is more common."
Watts is not energy, Watts is the unit of measurement for Power. A Coulomb, Joule or Killowatt-hour is energy.
"Now if you'd like to call the buck a "true energy converter" that's fine with me"
I never call it an energy converter. I called it what it is, a voltage converter. Besides it is electrical energy in, electrical energy out with a little unintentional energy conversion to thermal energy. Negligible because Buck converters are typically better the 98% efficient.
"The buck is referred to as a "true power converter" because it takes in one form of power (or energy) and puts out another form. So we have in the ideal case:"
One cannot change the form of power, there is only one kind. Energy a different story, there are many forms of energy.
"The difference between a quantity and a quality is that a quantity can be stated with a specific number while a quality is a very broad definition of something."
I did not use the word "quality", I used "quantity".
Energy is a quantity, Electrical Energy can be stated in Coulombs, Joules or Killowatt-hours.
Watt, the unit for Power is One Coulomb of energy per second or one Joule of energy per second, both are quantity/time the equation for rate.
"I am always open to further argument on either side, but in this case i dont see much elbow room."
Are you one of them ... Facts don't matter, your right?
Hi,
Thanks for the reply, but i think that's too many points to discuss all at once. Let's take it down to just 2 at a time ok? We can always come back to the others whenever it becomes clear that we've settled the first two.
I'll try not to be contentious and keep the discussion civil. You do have to realize though that you contradicted me on at least two or more points so you should expect some interesting replies
First is the issue of whether power is a rate or a quantity.
I have a converter, 24v input at 2 amps, and 12v output at 4 amps.
What is the power in, and what is the power out?
I stick a good power meter on the input, and a good power meter on the output.
I read "48 watts" on the input.
I read "48 watts" on the output.
Now how do i know that i dont have say 43 watts on the input or output or say 55 watts on the output?
It's because the QUANTITY is 48 not one of the others.
Is that the rate of energy too? Yes. That 48 is 48 joules per second.
So what you seem to be arguing here is a matter of semantics. I dont think that deserves further discussion because you'll just keep insisting and insisting because you seem to be a purist that seeks to change the way we use language. I've seen this before, most notably where someone insists that since "current is the flow of charge" if we say "the current is flowing through the wire" then that is incorrect because charge is already flowing, so it's is like saying "the charge flow is flowing"
These people will argue with you to no end and i dont think that is economical for me time wise.
Second what is a buck converter.
You said a buck converter does not convert power, it converts voltage.
That is a blatant mistake in observation of what a buck converter really does because it does more than that. There are things that convert voltage only and things that convert BOTH voltage AND current. The buck does the latter.
To understand this better, simply look at a linear regulator that takes in a higher voltage and outputs a lower voltage. Take the car battery for example, that needs around 14v to charge, and a solar panel of say 28v that can put out 1 amp at 28vdc. Connect a linear regulator (if you really wanted to that is). What do we see happen?
Experiment 1, linear regulator 28v to 14v DC:
We see 28v go in, and we see 14v come out, nice. But what is the current?
The current capability of the panel (at 28vdc) is 1 amp and the battery is drawing 1 amp, so the battery is drawing 1 amp and we see 1 amp from the panel. The power in and out is:
Pin=28*1=28 watts (call it a rate or a quantity as you prefer)
Pout=14*1=14 watts (ditto).
What happened to that other 14 watts, you know, the one that is also not a quantity (kidding)?
Did it disappear? I dont think so. In fact, it gets LOST as heat in the linear regulator.
Experiment 2, linear with different load:
Now change the charge in the battery so it only draws 0.5 amps. Note the panel also draws 0.5 amps.
Pin=28*0.5=14 watts (assuming slightly different solar insolation)
Pout=14*0.5=7 watts
Now we only loose 7 watts in the linear regulator.
Experiment 3, buck with 1 amp battery load:
Battery draws 1 amp at 14v, what is the panel current at 28vdc?
The panel current is now 0.5 amps.
What is the power in and out:
Pin=28*0.5=14 watts
Pout=14*1=14 watts.
What the heck, how did we get that they are both he same now?
Experiment 4, buck with 2 amp battery load:
Pin=28*1=28 watts
Pout=14*2=28 watts
What? We got the same power in as power out.
Now isnt it funny that in experiments 3 and 4 we got no power loss but in 1 and 2 we got lots of power loss. What is the difference?
The difference is that one is a true power converter because it takes the same power in as it delivers out. It converts Vin*In to Vout*Iout and we have in the ideal case the equality:
Pin=Pout
and that is why we call it a power converter, and a "true" power converter because the linear is not able to convert power levels like that it can only converter one thing like voltage or current, but not both.
If you dont see the difference now there's not much i can do for you.
How many books have you read on engineering in any field?
It is also funny but Wikipedia has an article on what you say does not exist:
https://en.wikipedia.org/wiki/Electric_power_conversion
There is some clarity in calling it a "power system conversion" i guess, but as common language would show, this gets shortened to simply "power conversion".
Another common device that is considered a true power converter is a power transformer. Oh wait, can i say "power transformer"?
Yeah, i guess i can
