What REALLY requires a pure sine inverter?

efficientPV

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I have several pure sine wave inverters, one is even a nice 3KW Xantrex. Somehow I have never even managed to use one. All the ones at my camp are MSW. I run my LG direct drive washer on a modified MSW inverter by feeding 130VDC from the panels right into the inverter and not using a battery at all. There were some phase triggered tool chargers that had some issues with MSW. Those were a cheap design that should never have been used. I use MSW and DC on PFC power supplies that some say won't work. It is a big world and there will always be something that doesn't work on MSW. Not enough to concern me.
 

rin67630

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We just should step back a little and look holistically at what we are really doing with electronics:
We use high tech electronics to produce -under considerable losses- from DC the perfect AC sine wave, that will be fed into a high tech power supply that will use considerable technological tricks to compensate the inconveniences of a sinusoidal waveform on rectifiers to produce... DC.
 

upnorthandpersonal

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But unless you go to 120V/240V or more DC, you have losses in transmission in your house wiring, or very expensive wiring. Then you have to convert this higher voltage DC, with considerable losses and through considerable technological tricks to a low voltage DC for your computer, LEDs, etc.
 

Ampster

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We use high tech electronics to produce -under considerable losses- from DC the perfect AC sine wave, that will be fed into a high tech power supply that will use considerable technological tricks to compensate the inconveniences of a sinusoidal waveform on rectifiers to produce... DC.
You are correct. But my hybrid sine wave inverter has all the bells and whistles to allow me to leverage my TOU rates and self consume as much as I can. My GT inverter allows me to sell back what i don't consume so I can use the grid as a battery. It is not perfect, but as a system it is reasonably cost effective.

It also allows me to charge my two EVs which store the energy in DC only to convert it to three phase AC. At least that is what the 2016 version does. The 2019 uses a permanent magnet motor and I see the words switched reluctance in some descriptions. I have no Ideas if either of those motors use a perfect sine wave but I do know they vary the frequency and the motors and inverters are matched to give me an EV grin.every time I hit the pedal.
 

rin67630

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You are correct. But my hybrid sine wave inverter has all the bells and whistles to allow me to leverage my TOU rates and self consume as much as I can. My GT inverter allows me to sell back what i don't consume so I can use the grid as a battery. It is not perfect, but as a system it is reasonably cost effective.
Grid-tied is of course a different story. It is the best battery, excepted where it is not available....
And your EV stores energy in DC just because no engineer has yet found a way to store AC energy.
 

rin67630

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But unless you go to 120V/240V or more DC, you have losses in transmission in your house wiring, or very expensive wiring. Then you have to convert this higher voltage DC, with considerable losses and through considerable technological tricks to a low voltage DC for your computer, LEDs, etc.
DC-DC conversion is easy and efficient.
 

Ampster

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Grid-tied is of course a different story.
It happens to be the story that most people live with. As I said earlier this is a theoretical academic discussion that has very little relevance to most people on the grid. It should be in the Danger Zone ( Advance Users Only) section of the Forum. I don't think many Off Grid users give a hoot.
Have fun. :LOL:

I will just keep rocking along with my GT inverter and my hybrid full sine wave inverter and my EVs.
 
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MurphyGuy

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Grid-tied is of course a different story. It is the best battery, excepted where it is not available....
And your EV stores energy in DC just because no engineer has yet found a way to store AC energy.

Pedantic Response Warning (Sorry)

That is technically true (can't store AC), but its not that simple or complete. The only way we know of to store DC energy is with piss-poor capacitors, and even our best technology hasn't produced a decent capacitor storage system that can hold a candle to a battery.

And on that note, with the exception of the flawed capacitors, we can't store DC energy anymore than we can store AC. If we want to store DC energy, we have to convert the energy into chemical storage, then reverse the chemistry to remove the energy.

So with DC, we are basically just shuffling electrons back and forth through chemistry and we incur losses both ways. If we consider the same game rules with AC, then we can store AC just as well as we can store DC.. Only instead of storing just the electrons, we have to store the entire atom.

This can be accomplished by moving mass to a higher elevation or through kinetic energy. Over in Europe, (The Swiss I think), they pump water up to the top of a mountain into a lake to store cheap (time of use) energy, then drain it back down through turbines to recover it.

We've also developed large massive flywheels that run on magnetic bearings inside a vacuum chamber. When thousands of pounds of mass gets spinning 40,000 rpm, it tends to be capable of producing copious amounts of juice when that energy is removed.

Storing DC energy is easier and more common than storing AC energy. Of course, if we put our pedantic physics hats on, that statement isn't really true either. E=MC² means energy is actually only stored within mass and velocity, everything else is just a conversion process with the unfortunate losses.

I did post a warning LOL
 

Ampster

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E=MC² means energy is actually only stored within mass and velocity,.....
Thanks for that reminder (and the warning LOL). As you mention pumped storage it is not just in lakes or reservoirs either. Germany is utilizing some abandoned coal mines for pumped storage.
 
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MurphyGuy

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Thanks for that reminder (and the warning LOL). As you mention pumped storage it is not just in lakes or reservoirs either. Germany is utilizing some abandoned coal mines for pumped storage.
They're even developing automated cranes now that lift and stack giant concrete Lego blocks. When excess power is available, the crane lifts and stacks blocks.. when power is needed, it grabs a block from the top and lets gravity generate energy as the block is lowered.

From an engineering perspective, it has a bit of a Fred Flintstone flavor to it, but no reason it can't work.

Too bad none of this stuff scales down to residential applications.
 

rin67630

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You could also ask, what really requires an inverter?

You are right: most power supplies labelled 100v-240V AC will perfectly run on 130V DC.
Indeed, even better.

The only BIG caveat, is that switching 130V DC is not trivial since you have no zero crossing to erase the arc between the contacts.
Normal switches will burn through at switching off.

But if you never switch and just plug off, it works 100%.

That is also the very reason I advocate MSW converters to feed electronic PS modules.
The square signal is ideal for them and there is an interruption 100 -120 times per second to erase a switching arc.
 

A.Justice

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Why bother with anything other than sinewave? If one wants to save money eliminate AC and go with DC. Edison wasn't completly wrong about DC?
Yep, I agree 100%. Most electronics (as stated by OP) turn the AC back to DC. It's WAY more simple to get a buck converter to run things off of DC directly. I use a 12 volt LiFePo4 battery bank, a lot of things take 12 volts anyway; TV, battery chargers, XBox, phone chargers, LED lighting, and modified desktop computer, will run perfectly without a DC converter.

I hate using my 12 volt system to power a 2200 watt inverter, it gets hot and pulls a lot of amperage, but I kept it at 12 volts for ease of hookup to pretty much everything, so I only use the inverter to run my freezer and fridge, everything else is DC direct.
 

rin67630

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1620939530402.png

That distribution box provides several 12V outputs, one being radio controlled.
It has two step-up DC-DC converters one to 19V, which is the charging voltage for many laptops and my soldering iron. and one 38V which is the voltage of my LED lighting system.
One adjustable step-down DC-DC converters provides voltages between 5 and 12V to charge various devices.
On the top-hidden is a cigarette lighter socket to plug many DC driven devices.

I never charge any of my devices from mains...
 

A.Justice

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View attachment 48895

That distribution box provides several 12V outputs, one being radio controlled.
It has two step-up DC-DC converters one to 19V, which is the charging voltage for many laptops and my soldering iron. and one 38V which is the voltage of my LED lighting system.
One adjustable step-down DC-DC converters provides voltages between 5 and 12V to charge various devices.
On the top-hidden is a cigarette lighter socket to plug many DC driven devices.

I never charge any of my devices from mains...
Do you have more pictures of the inside of that box? I'm working on something similar and would love some ideas!
 

pollenface

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Pedestal fans don't like msw inverters. They make a strange buzzing sound.

I have a 110w one in the back of my car for running laptop/phone chargers and hair clippers (when I need a haircut). Works fine for that and has lasted around 18yrs so far.
 

Rednek6966

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Pure sine inverters are expensive, but for which usage are they REALLY required?

Some will say: for powering sensitive electronics...
Did you really consider what mainly happens in >95% of today's electronics?
The AC input signal is rectified to DC before going to a DC-DC converter.
So it makes exactly NO difference if they get a pure sine or a modified sine.

Pure sine inverters are not only more expensive, they have a much higher quiescent current (no load loss) and a lower efficiency.

For which usages did you really experience that a pure sine inverter is absolutely required?
Speaking from personal experience, audio equipment of all sorts require pure sine wave. It will work on modified sine wave but the resulting buzz, hum and other extraneous noise make it impossible to enjoy. Guitar amplifiers, stereo equipment, etc. For this reason I use a 12 volt radio, a 12 volt guitar amp and have a pure sine wave inverter to run the 120 volt AC stereo equipment. I don’t have a TV and use portable devices for computers, laptops, iPads and iPhone. Modified sine wave works fine for toasters and most small appliances. Some light dimmer switches won’t work with modified sine wave as well. My wife’s sewing machine will work with modified sine wave but works better on pure sine wave. Some of the very elaborate computer controlled and expensive sewing machines should probably be used only with pure sine wave as well,
but I don’t have direct evidence for that and wouldn’t want to risk several thousand $$ or more trying to prove or disprove it.
 

Rednek6966

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Pure sine inverters are expensive, but for which usage are they REALLY required?

Some will say: for powering sensitive electronics...
Did you really consider what mainly happens in >95% of today's electronics?
The AC input signal is rectified to DC before going to a DC-DC converter.
So it makes exactly NO difference if they get a pure sine or a modified sine.

Pure sine inverters are not only more expensive, they have a much higher quiescent current (no load loss) and a lower efficiency.

For which usages did you really experience that a pure sine inverter is absolutely required?
As an afterthought, pure sine wave inverters are no longer that expensive. The prices have come down dramatically from the first ones I purchased.
 
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