Author Topic: Has anyone hacked or examined schematics for Inverter/Generator?  (Read 1273 times)

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alcul8r

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I have only seen block diagrams for I/G units, but have to ask, are the modules separate enough that you could add batteries, capacitors, and solar or wind in the middle to augment/replace the generator and/or charge batteries with the setup.

I'm asking mostly because they claim pure sine output and it would make an inexpensive Frankenstein unit.

Sorry if it has come up before, but I did the search and did not find anything.

Rex

joestue

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #1 on: January 05, 2017, 06:48:49 PM »
i don't believe its been discussed here yet.

you will need to deal with 200-300 volt dc bus voltage. so if you want to hook it up to a battery bank, you'll need to live dangerously.

Warpspeed

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #2 on: January 17, 2017, 04:04:41 PM »
I have never seen this anywhere else either, but its an excellent idea.

Doing it all at high dc voltage and low current means the efficiency will be very high.

I am doing something similar with a mains transformer rectifier, to generate a high dc voltage that drives an inverter direct to generate a pure sine wave.  That is how it runs at night.

During the day, all the dc power comes from solar panels at a high voltage, and there is no power drawn from the grid.

Its very simple, and there is no requirement to frequency lock the inverter to the grid, so the inverter is simple too.
As its not grid tie, and feeds nothing back,  the power utilities don't know I have this.

It would be pretty easy to add a wind turbine, standby generator,  or hydo to it.
A battery is difficult because of the rather high dc voltages required. But I use the grid as my night time battery.
A 360 volt lithium battery from a Chevy Volt would be one possible way.

If you have grid power available, a battery is really going to be uneconomic, unless you have very high night time loads.
My system supplies around 75% to 80% of consumption in summer.  I have yet to find out how well it will go through winter.  If it falls short, more solar panels should fix it.

OperaHouse

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #3 on: January 18, 2017, 12:33:59 AM »
I've been looking for one of these inverter generators for a while with a defective inverter.  I just imagine they use some hybrid parts that make them uneconomical to repair after they are out of warranty. I would then just use the  DC power and feed it to my inverter to supplement PV.  I have basically a battery less PV system and have to run the generator for high current loads like a washing machine.  I toyed with the idea of using my Onan 400W generator to do this.  It is well made and efficient. But, I think I will just add another 1,000W of panels and be generator and battery free. I can time slice washing to just stop during an occasional wisp of a cloud.

DanG

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #4 on: January 18, 2017, 10:39:35 AM »
Way back I glommed onto a Eu3000 shop manual with the point to point troubleshooting procedures just for the curiosity of  investigating multi-purpose inverter built in/around a Honda inverter generator...

360-400V DC is not something to be casual with; a DC boost module scabbed onto the Eu cover with wire runs insulated in 2000V silicone could accomplish transmission but then there is isolating the Honda alternator & diode sections without any chance of stray/leakage voltage, 400VDC likes to creep & arc, that would be a challenge even with solid-state switching.

Intercepting the overload &  over temp shut-down or current limiting commands, stability/quality of input power signals...  involves monitoring signals requiring conductor/trace access to component parts cast deeply in mil-spec encapsulation... It'd be neat to have jumper plugs to intercept all signals in and out of the Honda modules and some signal pick-ups surgically installed through the encapsulation but that is a lot of trial and error and a LOT of analog/digital sensors, essentially reinventing the wheel!

I'll see if I can find the manual, scan the theory of operation & electrics sections and have a PDF for the curious. No promises though...

Mary B

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #5 on: January 18, 2017, 02:02:24 PM »
400 volts is not bad at all and not to hard to deal with. The wire insulation will handle it if you use 600 volt rated wire and you don't need any special potting etc. I have built 2,500 volt 1 amp power supplies and never used any special potting. Design things with proper clearance so no arcing, use wire rated for that voltage(neon sign wire works very well), and use insulators to mount components above ground. At 400 volts arc distance in air is .001 inches, easily tamed!

Just beware that DC high voltage shocks can be lethal! One hand in the circuit, other one in a safe location not touching a ground! Stick it in your pocket! NEVER hold a chassis and work with live DC with the other hand! That puts the shock across your heart!

Warpspeed

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #6 on: January 18, 2017, 03:03:43 PM »
There are two main things to worry about with high voltage dc.
The greatly  increased lethality,  and huge dc arcs generated by the opening of switch or relay contacts.

My system uses two dc bus voltages +230v dc and -230v dc that run either side of mains neutral which is grounded.
The inverter is pure sine wave but its a simple half bridge topology.
Toggle switches that work fine on 230v ac  arc horribly for several seconds with 230v dc when I try to switch off dc test loads. 
So try to avoid the need to have any switching contacts in the dc part of the system if you can possibly avoid it.

If it cannot be avoided, use at least a two pole circuit breaker with the contacts connected in series.  These snap open very fast, and are designed to open while carrying enormous fault currents. 
A plain ordinary mains rated on/off switch will quickly die or even burst into flames switching similar voltage dc.

DanG

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #7 on: January 18, 2017, 06:32:38 PM »
I've worked with 800VDC & unlimited amperage. Umnn, letsee... never speak of HVDC in the wild as you would in a laboratory setting.

The converted inverter generator would not be in a clean room fire proof room, it'd be around people, children, animals. Also rain, lightning storms, humidity, dust, pollen, generator exhaust, metallic oxide from relay action, then add condensing atmospheres...  pollutants are endless. Also long term heating is involved so insulator breakdown is very likely, with heat comes raised tracking/creepage. Oh, and on top of the above add in storage in uncontrolled environments and the likelihood of being pressed into service without inspection/cleaning we'll toss in insect & rodent intrusion.

Having the HVDC ground plane with a raised resistance level will help in current limiting so double/triple insulated . Using an instant acting C/B's, GFI or arc detection, along with a current limiting fuse to catch leakage and runaway arcing...  hmnn, maybe we should be looking at used 600VDC solar gridtie modules for their safety products..

frackers

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #8 on: January 18, 2017, 07:55:23 PM »
Not quite on topic but associated with switching high voltage DC, I'm planning on regulating my AC coupled grid tie outputs by switching the solar panel inputs on/off in 2.5kw increments.

This may not at first sight look to be a good idea!! but I have a pair of 5kw grid tie inverters that each has 2 independent MPP trackers. I really don't want 10kw pushed into my batteries  (or even have 5kw increments) hence the switching idea with some sort of limit of once per 5 minutes (to allow for the trainup time of the inverter). The main aim is to have fast cutout for charging safety and rely on the batteries to handle loads until the next solar string can be brought online.

Since relays to handle over 400vdc open circuit run to 10's of $ I'm planning on an IGBT to do the high voltage switching with a relay across it to reduce the dissipation (8A @ 2.5V soon adds up).
To turn on, the IGBT switches on, followed by the relay.
To turn off, the relay opens followed by the IGBT.

The power for the relay coil and the bias for the IGBT would be derived from a transformer with dual 12v windings (one for each MPPT string) and controlled via an opt isolator from the system charge controller. I would expect the isolation on a standard (240v) mains transformer should be OK for the 400v floating about, although I suspect that one side of the string is grounded as the inverters have built in ground fault protection.. No idea what sort of snubbers I'd need for this arrangement to protect the IGBT from any spikes, perhaps someone here has some ideas!


Robin Down Under (Or Are You Up Over)

Mary B

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Re: Has anyone hacked or examined schematics for Inverter/Generator?
« Reply #9 on: January 19, 2017, 06:17:26 PM »

My house is dusty, cat fur, occasional smoke from the pellet stove, cooking grease and fumes... these 2500 volt supplies sat on the floor and were literally coated in dust inside at times. No issues, if one arced it blew the fuse and told me it was time to clean it! A way to limit the current on HV lines is use a high wattage 5-25 ohm(or smaller than 5 if needed) ceramic resistor in series with the HV line. In ham amplifiers it protected the tube in case of internal tube arcs...

I've worked with 800VDC & unlimited amperage. Umnn, letsee... never speak of HVDC in the wild as you would in a laboratory setting.

The converted inverter generator would not be in a clean room fire proof room, it'd be around people, children, animals. Also rain, lightning storms, humidity, dust, pollen, generator exhaust, metallic oxide from relay action, then add condensing atmospheres...  pollutants are endless. Also long term heating is involved so insulator breakdown is very likely, with heat comes raised tracking/creepage. Oh, and on top of the above add in storage in uncontrolled environments and the likelihood of being pressed into service without inspection/cleaning we'll toss in insect & rodent intrusion.

Having the HVDC ground plane with a raised resistance level will help in current limiting so double/triple insulated . Using an instant acting C/B's, GFI or arc detection, along with a current limiting fuse to catch leakage and runaway arcing...  hmnn, maybe we should be looking at used 600VDC solar gridtie modules for their safety products..