Google Offers a Million Bucks For a Better Inverter

On a sunny day (25 Jul 2014 11:56:13 GMT) it happened Jasen Betts wrote in :

Yes, Weller, but I now have a Voltcraft LS50:

But indeed it is 24V google finds this:

Best soldering iron I ever had.

Getting 24 Vdc computers for industrial applications should not be that hard these days. .

On a sunny day (25 Jul 2014 11:56:13 GMT) it happened Jasen Betts wrote in :

PS what I want to do is find the bridge rectifier and add a DC input there. Hopefuilly the Micro does not use 50 Hz It has a micro, a thermocuple, some CMOS, and an opamp, want to keep the circuit.

Most gadgets with transformers inside, use them to reduce the mains voltage from 240 or 120 volts to something more like 12 volts; they also almost always have some form of 'rectifier' to provide the DC current they actually need.

The cavity magnetron (the essential part of a microwave oven) requires direct current supply, so ovens sold to work off AC mains must have rectifiers inside to get the DC required. Electronic circuits control the actual voltage supplied to the magnetron - they also require DC.

They only require an AC supply because that's what they're designed to operate from. Their output is almost always DC. They could be designed to run from a DC supply instead - but if the DC supply is already at an appropriate voltage for charging things, the 'wall wart' can be a very much simpler device running entirely on DC.

The fluctuating current in the induction coil is generated electronically, the frequency is much higher than the 50 or 60 Hertz of AC mains.

Fridges designed to run off DC power (eg in caravans or campervans) use DC motors - or have no motor at all, using the 'absorption' cycle instead of compression.

I don't think either Google or I mentioned using 120 volts DC for anything. Domestic appliances on DC are designed for much lower voltages, typically less than 20 volts.

There's your first big mistake.

You used AC components on a DC circuit. Bad mistake, and certainly not suggested by me.

A 'universal' motor without a load will over-speed uncontrollably if fed with a DC power supply - and using 120 volts DC will just make it even more exciting. Silly idea, not suggested by me.

Just as well, sounds as though you were creating a death trap. Had you not heard of 12 volt DC appliances? They've been around for a long time.

Did you know this before you experimented as described above?

Who suggested using 120 volts DC for anything? Not me, or Google. Google want to get 120 volts AC out of a low voltage DC supply; I pointed out that if you haven't got a collection of 120 volt AC gadgets (which you won't if you've never had a mains supply or a generator substitute for one) then it makes more sense to get DC appliances and thus make the inverter redundant.

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-- ^^^^^^^^^^ 
--  Whiskers  
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On the face of it, for any non-zero level of harmonic distortion in the voltage, a choice of component values will allow the current at the fundamental frequency to be made arbitrarily small compared with the currents at the harmonics.

Which is to say, there always exists a load that will make an inverter fail to meet the harmonic current requirement.

Sylvia.

In microwave owns, the magnetrons _is_ the rectifier tube.

If the HV DC is available, it can simply use it.

When you pull the telephone from the charger, if the charger remains warm after that, it remains warm (iron core transformer), however, if it remains cold, there is an DC/DC switcher on the mains side, so a DC supply would be just as OK.

Absolutely.

Running a compressor with VFD is non issue.

Perhaps Google are looking forward to cheap foldable solar panels that can be packed into a pocket and then unfurled as required; an inverter that would fit in another pocket might then be attractive - although anyone sufficiently concerned about weight and volume, is unlikely to be carrying anything that needs more than a few volts DC anyway.

But we now have electronic circuits that can change DC voltages quite efficiently.

High voltage direct current power transmission is the new big thing, eg, connecting the 'national grids' of Ireland, England, and France, via undersea cables.

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-- ^^^^^^^^^^ 
--  Whiskers  
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I am alone in wondering why if it requires an entire roof full of solar PV panels to power it that the thing being roughly about coolbox sized is not a significant barrier to the technology being distributed.

The high cost of the PV panels is the biggest factor, followed by the difficulty in storing daytime electricity for use at night.

Whilst it might be amusing to make a smaller one it isn't going to alter the economics of solar PV installations which are dominated at present by the cost of the array of pure silicon installed on the roof.

Regards, Martin Brown

Yes, it is likely the two phased 240V with center ground neutral. This is how building main electrical box is wired in the US (and likely the spec writer's house).

Not for this project, but yes for a real project.

No.

You have to treat it as a true two phased AC system. The fact that they don't measure neutral does not mean that you don't have to consider it.

Yes, i had burnt out many appliance transformers with unbalanced neutral.

Eventually, it should be scaled down to one inverter per panel and multiple systems per household. But that mean grid-tied.

Yes, that means grid-tied.

Perhaps the next challenge is a 200W inverter running inside an Android phone.

One of them.

Usually as part of a half wave doubler with shorted output (so the diode gets all the energy, for obvious purposes).

Tim

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Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com

Nobody is concerned about storage for later use, the main thrust presently and for the past 20 years has been to offload the peak demand requirements on the grid. And then for practical purposes of economy, being able to sell excess capacity to the power company during hours of peak demand could con ceivably make the individual installation a net zero energy user, so why go to the relatively large expense (and hazard) of storage.

Ummmm, half wave doublers at line frequency have been dead and gone for nearly twenty years now, let's try the resonant converters operating at 36KHz for a more relevant discussion.

(not in form of battery)

Just a matter of speech. Everybody is concerned about storage of under-uti lized solar energy; and thus the grid-tied feature.

he peak demand requirements on the grid. And then for practical purposes of economy, being able to sell excess capacity to the power company during ho urs of peak demand could conceivably make the individual installation a net zero energy user, so why go to the relatively large expense (and hazard) o f storage.

Exactly.

It's a fair cop guv!

I'll do my penance. What's more I promise not to rebuke such an easy target as Nymbecile ever again.

tilized solar energy; and thus the grid-tied feature.

the peak demand requirements on the grid. And then for practical purposes of economy, being able to sell excess capacity to the power company during hours of peak demand could conceivably make the individual installation a n et zero energy user, so why go to the relatively large expense (and hazard) of storage.

Furthermore, it will reduce transmission power lost if power is generated c loser to the demand. I think Google came to the same conclusion with their fiber buildup. They need distributed power generator everywhere.

By the way, I started working on distributed power inverter around 2 years ago. Here is a circuit and layout I posted 5 months ago. However, it will need to be changed for GaN transistor, with a different package.

There were also some discussions on booster/regulator/inverter designs if y ou remember it.

I will release my full design in September.

One trade name is an "inverter microwave oven", usually from Panasonic. The pitch line: I have one and it works really nicely. The only problem is that it has features that I don't have a clue how to use, even after RTFM.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

You might find it useful to re-read what you posted. To me, it sounded like a proposal to eliminate the inverter idea because the house and its appliances can be operated from DC. Is that correct or did I misread your comments?

Yep. You can replace all the AC appliances with low voltage DC equivalents, while also replacing all the wall outlets, wall switches, breaker panel, circuit breakers, power meters, and beefing up the copper wiring to deal with the IR losses. In other words, your suggestion of using DC requires replacing almost everything electrical in the house.

Blame the messenger? I used every opportunity to warn them that this was a dumb and unsafe idea. Nobody listened. I did my best to not kill anyone (including myself) and succeeded.

True. You didn't specify any operating voltage. All you said was that the Google inverter was not necessary because appliances can run on DC. I assumed 120 VDC. Got a favorite home distribution voltage in mind? 12v 24v 48v or more?

Ever wonder why the strange looking cooling fan on many such motors? At very high speeds, the fan produces enough air drag to prevent the motor from spinning too fast. In the case of the Skil Saw on DC that I mentioned, the drag from the worm gear, grease, and gearing was sufficient to prevent overspeed. It didn't do much for the arcing and contact welding problems, but it didn't overspeed.

Incidentally, Dremel tools, blenders, vacuum cleaners, hair dryers, and weed trimmers are examples of universal motors, some of which run without a load or rely on armature drag to limit overspeed. Most run on AC, but will run at many revolutions per AC cycle, making them a good candidate for running on DC.

Certainly. However the owner and builder decided not to build a stationary home full of camping supplies. Using 12v was an option, but nobody could figure out how to cram the necessary heavy cables through the 3/4" PVC conduit. Please note that the arcing and contact welding problems I experienced would have been much worse at 12v DC than at 120V DC.

No. I've been a subscriber to Home Power magazine since their beginning in about 1987. The house in question was being built around

1978 - 1980. I'm not sure about the year. In college, during the 1960's, I took several classes and labs in electrical principles and applications. I also worked as an electrician for one summer, although most of what I did was grunt work. I'm not an electrician or an expert on appliances, motors, or alternative energy, but can usually fill in the gaps between my experiences with basic principles and theory.

You said that AC was not necessary. That means you're proposing using DC. All that's lacking is for you to specify a working distribution voltage. 120 VDC seems an obvious choice, but equally obviously, you must have a different number in mind. What is it?

Please re-read the specs. The input voltage is 450 VDC through 10 ohms. That's not low voltage unless you spend your days dealing with lightning bolts.

What voltage DC appliances?

I once lived in a trailer and on a Chinese junk (baby sitting the owner cat) that had all DC appliances. I have friends in similar living situations. I also know of several households living off the grid. There's one thing in common about all of them. They all detest

12v appliances and much prefer common 117v AC appliances.

What voltage do you propose?

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

LOL- like any of those features have anything to do with the converter technology...My GE walks me through anything I have to do by scrolling directions across the VFD after a suitable delay like 10 seconds.