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[pacificcricket]

Came across this :

https://www.tame-power.com/en/dc-dc-power-converter/isolated-dcdc-converter-7kw-80-150v-reversible

Looks like it could work, but would it be more practical than high power AC options ?

[Crissa]

It's possible, it's just not energy efficient or cheap

[DonTom]

Came across this :

https://www.tame-power.com/en/dc-dc-power-converter/isolated-dcdc-converter-7kw-80-150v-reversible

Looks like it could work, but would it be more practical than high power AC options ?

Work for what?  I  see no advantage of charging by starting with DC to convert it to AC to convert it back to DC. Just a lot of loss for nothing.

DC to DC converters work by changing DC to AC and then changing the voltage and then converting back to DC.  So why not just use an AC charger to begin with?

-Don-  Reno, NV

[Crissa]

DC-DC converters do not usually use AC at all; AC voltage stepping may be nearly completely efficient (one of the reasons we transmit AC), but it's very bulky to make AC so it's rarely done that way.

But they are inefficient.

-Crissa

[DonTom]

DC-DC converters do not usually use AC at all

So how would a DC in of ten volts get to 100DC  volts with no AC involved?

"How does a DC Converter Work? The basic DC-DC converter will take the current and pass it through a "switching element". This turns the signal into a square wave, which is actually AC."


-Don-  Reno, NV

[NoMoreIdeas]

By using a switching power supply by means of an inductor and a capacitor: https://components101.com/articles/boost-converter-basics-working-design

[DonTom]

By using a switching power supply by means of an inductor and a capacitor: https://components101.com/articles/boost-converter-basics-working-design

It really depends on what we call AC and DC.  Does the sawtooth waveform in your own  link look like DC to you? It certainly doesn't  to me. Not even close to DC. But very close to AC.

Besides, that, it's still very inefficient as I said in my first post on this subject.  Better off to start out with AC and use no switching of any type, regardless of what you call the waveshape after the switching.  But I would never call it DC at that point.

-Don-  Reno, NV

[NoMoreIdeas]

By using a switching power supply by means of an inductor and a capacitor: https://components101.com/articles/boost-converter-basics-working-design

It really depends on what we call AC and DC.  Does the sawtooth waveform in your own  link look like DC to you? It certainly doesn't  to me. Not even close to DC. But very close to AC.

Besides, that, it's still very inefficient as I said in my first post on this subject.  Better off to start out with AC and use no switching of any type, regardless of what you call the waveshape after the switching.  But I would never call it DC at that point.

-Don-  Reno, NV

Well the current doesnt alternate, so its not AC. Its DC that is switched very fast. Most switched power supplies are in the >85% efficiency range. Besides how do you think your AC charger converts AC to a variable voltage DC?

[pacificcricket]

just not energy efficient or cheap

According to the datasheets some of their models push 95-96% efficiency. So I'd say they're quite efficient. Cost I don't know... mostly wondering about the packaging - can they be smaller / lighter than say diginow chargers with the same power output.

[DonTom]

Well the current doesnt alternate, so its not AC. Its DC that is switched very fast. Most switched power supplies are in the >85% efficiency range. Besides how do you think your AC charger converts AC to a variable voltage DC?

Not true AC, but I realize that "alternating"  DC  off and on is often used much like AC  where DC will not work at all. Yes, it's efficient if it's not another wasted stage that has no benefit.  I have been using the term AC a bit too loosely here for some but I do understand how it's used.

-Don-  Reno, NV

[BrianTRice@gmail.com]

Yes, it’s practical in principle.

No, the choppy output of a converter isn’t “AC”. AC, when produced by a switching power supply, is an emulated sine wave made by alternating the peaks of those choppy segments.

Choppy DC output is fine (smoothed over with circuitry). That’s what switching power supplies that are chargers already perform.

However, level 3 charging involves a negotiation and control protocol (CCS or CHAdeMO) on top of it that comes with R&D costs, along with fabricating a safe enclosure with a properly wired inlet.

Just wiring up a low-IP-rating converter isn’t going to get you much further than the CHAdeMO Zero tail case attempt, which turns on with a transient and then cuts off.