Warpverter: How would I build a second one?

[jgh]

So, four primaries would need four separate switching bridges only? No different to the four-transformer version?
And still generate the same 81 steps?

 

[Hedges]

I don't think so - I don't think you can have two primaries of different turn counts on a core, and connect both through FETs to same voltage.

What you might be able to do is connect all the primary drive FET H-bridges in series, and connect that to a battery.
Not sure, that would need to be thought through.

If it did work, should not be a big deal to have a bunch of windings on a single core. That has always been common.

 

[doing it different]

What is your thoughts on this unit...
HV battery... but does it work similar but with no transformer???

I just found this on AliExpress:
C$12.58 | Pure Sine Wave High-power IGBT Module Control 2000A Driver Board

https://a.aliexpress.com/_mrTzP0j

 

[rustyrotors]

for those running warpverters, how much idle power does it pull, and how much transformer do you have (kW). is it less than a typical single trans LF inverter of same rating, since dont have to deal with 20kHz+ switching loss, or is it about the same, depending on trans design

i run a homebrew egs002 5kW, only uses 20W idle, which is about 5% of my battery. it would be nice to upgrade to 10kW, but not sure about increased idle draw

 

[Warpspeed]

for those running warpverters, how much idle power does it pull, and how much transformer do you have (kW). is it less than a typical single trans LF inverter of same rating, since dont have to deal with 20kHz+ switching loss, or is it about the same, depending on trans design

Both zero load idling power and flat out efficiency will be about the same or very comparable between a Warpverter or a PWM transformer inverter.
There is a bit of luck involved with the quality of the steel in the transformer cores, and that applies in both cases.

As regards actual idling power, my own 5Kw Warpverter, idling power is 35 watts. About 5 watts of that are for the control board.
Rogers 15Kw Warpverter is also 35 watts.
I believe the best effort so far is 20 watts of idling power for a 7.5Kw Warpverter.

 

[Warpspeed]

What is your thoughts on this unit...
HV battery... but does it work similar but with no transformer???

I just found this on AliExpress:
C$12.58 | Pure Sine Wave High-power IGBT Module Control 2000A Driver Board

https://a.aliexpress.com/_mrTzP0j

The larger IGBTs are slow, so the PWM switching frequency must also be fairly low.
Sure it would work, but if something goes wrong with it, it can quite easily put a constant high dc voltage onto all your precious household appliances.
That would be a very sad and expensive day you will never forget.

I learned that particular lesson the hard way myself.
Worth a try, but PLEASE put an isolating transformer between the inverter and any appliances you value.

 

[doing it different]

The larger IGBTs are slow, so the PWM switching frequency must also be fairly low.
Sure it would work, but if something goes wrong with it, it can quite easily put a constant high dc voltage onto all your precious household appliances.
That would be a very sad and expensive day you will never forget.

I learned that particular lesson the hard way myself.
Worth a try, but PLEASE put an isolating transformer between the inverter and any appliances you value.

Isolating Transformer... Yeah that would make alot of sense.
I'll probably not be ordering it.

I am still trying make sense of it all.
I understand basic electronics.... and even tinker and fix some stuff. But alot of the control side of things for inverter is abit over my head...
Thanks I'll not derail the thread any more

 

[rogerdw]

for those running warpverters, how much idle power does it pull, and how much transformer do you have (kW). is it less than a typical single trans LF inverter of same rating, since dont have to deal with 20kHz+ switching loss, or is it about the same, depending on trans design

i run a homebrew egs002 5kW, only uses 20W idle, which is about 5% of my battery. it would be nice to upgrade to 10kW, but not sure about increased idle draw

I'm sorry, for some reason I haven't been getting notifications on this thread. Been getting them on all the others okay.

I'm glad Tony is around to answer questions.

As Tony said, my 15kW Warpverter has a idle power of 35 watts. I remember when I first started looking into inverters, some of them were wasting 200 watts at idle.


I see this morning that it's just clocked over 10,000kWh since I installed it back in March last year. Thrilled that it has gone so well. Thanks Tony.

 

[Warpspeed]

That represents quite a few dollars.

 

[rogerdw]

That represents quite a few dollars.

Yep, that's $5,000. Our rates were 50.5c/kWh for a while but they dropped to ~49.5.

Won't be too long and I'll be able to pour plenty into our underfloor heating to get ready for winter. At the moment the only thing using a bit are the pool pumps.

 

[rogerdw]

I thought it was time to update the thread. Today is the first anniversary of when the Warpverter was installed on our property and been allowing us to run offgrid since. There was a bit of battery charging from the grid over winter ... but for 7 or 8 months we used no grid power at all.

Just recently I've made some changes which required switching over for a couple hours ... several times ... but generally that is only for maintenance or emergencies.

As mentioned over on Tony's Warpverter thread, I recently fitted a new control board which in addition to the voltage feed forward control ... now adds in a current feed forward control. I fitted a Hall Effect current sensor on the main dc input inside the inverter ... and the extra few components on the control board monitor that and prevent the ac out from sagging under heavy loads.

Eg with a >10kW load, the ac output may drop by about 10 volts. No real drama, but was nice to improve that. I haven't run past about 7-8kW loads so far ... but it now stays within a 2 volt range. I have more experimenting to do to fine tune it some more if possible.

One of the recent jobs was to fit a barrel fan at the bottom to cool the toroids and the heatsink ... though the heatsink never gets more than a few degrees above ambient. The toroids can certainly get hot on a warm day and with big loads ... so an automatic fan is a good idea.

While the fan all fits nicely, I stll need to build some shrouds to channel the air correctly ... though anything is better than nothing.

I also changed over the shunt and dc power monitor for an equivalent wifi version ... but while it worked ok to show the readings ... the main function I wanted ... the wifi feature would not work. Then I had to spend another couple hours pulling it all out to return it and get a refund.

I'd still like a wifi version, so I'll have to do it all over again eventually!!!

So far the Warpverter has generated 11,461kWh of power and has saved us an appreciable amount of money. The first bill with the overlap period was $1,088/qtr, 2nd $186, 3rd $0, 4th $0. The last full bill before that was up around $1,300/qtr.

I had our ac-coupled 5kW Growatt turned off pretty much the last 6 months as we simply can't use all the power ... but with our autumn just started, it won't be long and I'll be turning on every bit of heating the system will run. It made a huge difference last winter being able to use a lot of electric heating ... rather than burning our wood heater for months and months ... in fact we only ran it for two months instead of the usual five months. Another big saving in time and effort.

Overall, we are thrilled with the unit and it's been a very worthwhile investment.

 

[rogerdw]

I don't have any immediate plans to build another Warpverter ... but I'd never look past any potential bits I might need if I ever were to get the urge again.

There was an online auction a couple weeks ago with a heap of solar stuff and I couldn't help myself when I saw these toroids listed. There were 3 crates of 16, another crate of 8 ... and this lovely little group of 5 with my name on them. The pickup point was only going to be an hour away, so I wasn't concerned about the freight.

When I saw the crates of 16 suddenly go well over a thousand dollars in the last few minutes, I figured I was going to miss out ... but it seems they were fighting over the big lots and left me alone. With fees and charges, this 5 cost me $125 AUD in total.

Believe it or not, they each weigh 35kg / 77lb

They are 5000VA ... with secondary of 240v @ 20.83 amps


The other smaller toroid in the picture weighs 17kg ... and is a 3000w toroid from an Aerosharp inverter. I used four of those to build up the large transformer on the Warpverter ... and used a fifth one to rewind for the second largest transformer.

I have no idea what these would cost to buy new ... but I would hazzard a guess of at least $1,500 each ... maybe $2,000. Even from Aliexpress they could easily cost that because of the freight.

 

[Warpspeed]

Golly !
You certainly find some pretty cool stuff Roger

 

[rogerdw]

I did have a thought. If I hooked three up to my 13kva 3phase generator, one on each phase ... then connected 3 of the primary windings in series for about 65v ... then through a bridge rectifier and straight to the battery.

No regulation, but I have an electronic governor on the generator ... so I could just throttle it back to prevent overcharging.

Dunno if my sums are right ... but that should give me maybe 150 amps of charging.

 

[Warpspeed]

Does your three phase generator have a neutral ?

 

[rogerdw]

Does your three phase generator have a neutral ?

Yes.

 

[Warpspeed]

O/k no problem connecting three primaries in star with the neutral connected then.

I would connect the four 21.82v windings 2S2P to create 43.6v rms at 40A. and connect that via a four diode bridge to the battery.
Do likewise with the other two transformers.
Each diode bridge will produce 61.7v peak minus two diode drops or probably about 59v dc when fully loaded.

In theory, you could connect the three secondaries in delta and use a single six diode bridge (and save on diodes).
But if you do it that way, if the three sine wave voltages are not perfect sine waves, you can get circulating current when you close the delta connection between transformers. That just heats up the transformers unnecessarily and makes the alternator angry

By using three completely separate four diode bridge rectifiers, there can no circulating path around the three transformers for harmonic current to flow, and it will be potentially a lot more efficient, especially if the sine waves coming from the alternator are slightly horrible..

 

[Warpspeed]

Its normal with three phase rectifiers to use a star connection to drive a six diode bridge. That eliminates the circulating harmonics that you get with a delta connection. But with the secondary voltages available from the transformers that you have, its not really possible to come up with a star connected combination that can provide anything like suitable dc voltage to charge a 48v lead acid battery.

 

[rogerdw]

Thanks for the explanation Tony, I didn't put enough effort into the numbers. I do have access to a 120 amp 3phase battery charger, so that is probably easier to use ... but if it turns out that is not functioning or fixable I may just try the toroids.

I still need to obtain a generator management system for the generator as I'm not too keen leaving it running for hours unattended. At least with oil and coolant monitoring, I can relax while it's charging. I need to get onto it as winter will be here before we know it ... though with the temps we have at the moment, it's still like the middle of summer.

 

[Hedges]

By using three completely separate four diode bridge rectifiers, there can no circulating path around the three transformers for harmonic current to flow, and it will be potentially a lot more efficient, especially if the sine waves coming from the alternator are slightly horrible..

Its normal with three phase rectifiers to use a star connection to drive a six diode bridge. That eliminates the circulating harmonics that you get with a delta connection. But with the secondary voltages available from the transformers that you have, its not really possible to come up with a star connected combination that can provide anything like suitable dc voltage to charge a 48v lead acid battery.

I was about to say, "For a WYE connected generator ?? Feeding one DC bus ?"

But then I remembered

There was an online auction a couple weeks ago with a heap of solar stuff and I couldn't help myself when I saw these toroids listed. There were 3 crates of 16, another crate of 8 ... and this lovely little group of 5 with my name on them. The pickup point was only going to be an hour away, so I wasn't concerned about the freight.

With three isolation transformers, no problem.

I would have thought connected to either the legs of the WYE or to the Delta it would be fine.

"That eliminates the circulating harmonics that you get with a delta connection."

What is the problem? I thought WYE generator wants Delta load, and Delta generator wants WYE load.

But I don't really understand the circulation issue.
Except, when I fed imbalanced 3-phase 120/125/125 with neutral into a WYE transformer, it had much more no-load current than I wanted. That was 3-phase Sunny Island fed from single-phase grid, making the missing phases.
I got it working better by disconnecting neutral (purpose was to feed 3-phase TriPower GT PV).
I think 3 independent toroid auto-transformers had worked fine. Just not the E-core 3-phase transformer.

 

[Warpspeed]

Except, when I fed imbalanced 3-phase 120/125/125 with neutral into a WYE transformer, it had much more no-load current than I wanted. That was 3-phase Sunny Island fed from single-phase grid, making the missing phases.
I got it working better by disconnecting neutral (purpose was to feed 3-phase TriPower GT PV).
I think 3 independent toroid auto-transformers had worked fine. Just not the E-core 3-phase transformer.

Yes, you are quite right.
Wye connection (star) can only function as a true wye in the primary if the neutral centre point is left floating.
If you tie down the neutral then the secondary voltages if they are not exactly equal, and also perfect sine waves will produce a resultant error voltage, and you cannot then close the delta connected secondary without a big splat.
It is possible to run what the electrical engineering guys call "open delta" which is virtually what I am proposing here.

I have actually tested this three individual bridge rectifiers in a three phase circuit idea myself, even have pictures of the test setup here somewhere, and the results were quite interesting.
You have three individual floating secondaries, each fitted with a full wave bridge rectifier.
If you connect the three dc outputs from the rectifiers in parallel, you get the expected usual peak dc output voltage with only about 4% of ripple.
If you connect the three dc outputs in series, you get exactly double the peak voltage, again with only about 4% of ripple.

This might be useful for the wind turbine guys to reduce cut in speed at low power, but I don't know if anyone has ever tried it for that.

 

[Warpspeed]

I could only find one of those old pictures dating back seven years.
Here is a three phase transformer with three individual bridge rectifiers connected in parallel.
A rather unconventional way to do it, but I also had suitable busbars to connect those three rectifiers in series.
That exactly doubled the dc output voltage by doing nothing else.
It was interesting because that transformer has three secondaries available on each phase, plus several tappings on all the primaries.
I was curious to see what dc output voltage I could obtain with the many different possible combinations.

 

[Hedges]

Interesting ... was hoping for a ripple-free DC out, but that's going to take 3-phase PFC AC/DC converter.

For a moment I thought you referred to three windings required in series (zig-zag), but realized and then read you meant after rectification. Oh, that's not zig-zag, need 3 pairs in WYE, not 3 in series or you get zero:



Straight line at zero was sum without rectification, ripple on top is with.

function sumSine

%SUMSINE Study effect of rectifying and summing sine wave.
% Detailed explanation goes here

% Usage:
%
% sumSine
%

freq = 60; % Hz
time = 1; % second
stepsize = 1/10000; % seconds

t = 0:stepsize:time;

phaseAngle = 2*pi/3; % 3-phase
phaseL1 = 0; % radians
phaseL2 = phaseL1 + phaseAngle;
phaseL3 = phaseL2 + phaseAngle;

amplitudeVrms = 120; % volts
amplitudeVpeak = amplitudeVrms * sqrt(2);

L1complex = amplitudeVpeak * exp(-j*(2*pi*t+phaseL1));
L2complex = amplitudeVpeak * exp(-j*(2*pi*t+phaseL2));
L3complex = amplitudeVpeak * exp(-j*(2*pi*t+phaseL3));

plot(t,real(L1complex));
hold on
plot(t,real(L2complex));
plot(t,abs(real(L1complex))+abs(real(L2complex))+abs(real(L3complex)));



end

Works in volts. I think it shoves current through transformers when they weren't planning to source it, much like your papa/momma/baby bear transformers. Or does that go through diodes? Must be sucking current not in proportion to voltage, anything but 1.0 PF.

LTSpice, paralleled small ripple as you say. Gulps of current from each phase when it is above others.



Series, double voltage and still gulps of current, but not sitting at zero. Always a peak but not positive or negative.
Warpverter just transfers it to primary. Instantaneous current change generates back EMF at least due to leakage inductance.
Hate to think what HF inverter would do faced with that.

 

[Warpspeed]

The concept has vague similarity to a twelve pulse rectifier, which is a fairly common way to get a lot of very high power dc that has an even lower ripple content, without requiring any subsequent filtering.
These kinds of circuits have been around for well over a hundred years.

The voltage waveform in your previous post #148 above ^^ is exactly what I was seeing.
Three phases each of about 160v peak, produce around 320v of low ripple dc.

 

[Hedges]

Right, WYE & Delta would double number of peaks.

But the unique thing about floating, rectified, series connected is they have to pass the current generated by the other phases.
Oh, at least it is in phase. I thought some were going to be out of phase: