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Forum Index : Electronics : Inverter building using Wiseguys Power board and the Nano drive board
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Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458
Posted: 12:39am 17 Jul 2024
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Hi Mab, I have just setup a GTI inverter backfeeding with my home made aliexpress 8010 inverter. It works fine, no problems backfeeding. I would think that if you have two different transformers then you would need a way to turn one off when backfeeding otherwise the smaller one may be overloaded. I am using a 5kw GTI on 3600 watts of panels, and backfeeding/load sharing with my 5kw 8010 aliexpress inverter. The battery inverter is really not good on its own for more than about 3600 watts as my setup is 24 volt. But when charging the car the GTI does most of the work, I am just using battery voltage settings to turn the GTI on and off with its anti islanding settings as suggested by Murphys friend. Pete
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 12:43am 17 Jul 2024
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I believe wiseguy made it clear that you cannot mix transformers sizes and they must be sized and wound exactly the same. The nano sees the inverter as one 12KW single unit. It is divided by 2 identical wound transformers running off 2 mainboards running off 1 single controler board. Wiseguy is working on another addon board that gives you the ability to turn off one of the transformers to save idle power and you have the ability to keep it in auto 6KW to 12KW switching mode or have the ability to switch on 12KW mode manually. There are also other safety features as peek current monitoring etc… As for me since I only have a few devices that draw a lot of power for a short while like the water maker, dive compressor and of course the MIG welder which started this whole needing a 12KW inverter in the first place. Wiseguy has steeped up the game in having this very unique feature where you can run an inverter at 6KW mode and save idle power or have it switch to 12KW mode automatically without blowing anything up or have the ability to manually switch to 12KW mode when you know you need the extra power. It’s an absolute brilliant design and very unique as I have never seen this feature in any inverter before.
mab1 Senior Member Joined: 10/02/2015 Location: United KingdomPosts: 209
Posted: 01:10am 17 Jul 2024
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Well it was a theory - i don't need it myself so i wasn't planning on experimenting, though that would be the way to prove it. But it would give the potential for a greater power saving than 50% in low power mode.
The two transformers would have to have the exact same primary/secondary turns ratio, even though the smaller transformer would have more turns per volt. But i don't see that it wouldn't work, it's more a question of whether or not the transformers share the load as intended.
Godoh: glad it's working well for you. I already have gti's back feeding my powerjack inverter; i have had 4 gti's back feeding at once with lots of diversion loads to stop them overloading the powerjack, but only have two at the moment. But it would be nice to know if wiseguys inverter can handle it in advance - but I end up the first to try so be it.
poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1418
Posted: 01:12am 17 Jul 2024
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The 3kW Victron inverter I had drove two toroids in the same way as you describe. It's a great idea to reduce energy losses.
Victron designs are "unique", but not in a good way. Another thing they do is they have the toroids wound in such a way there is a lot of leakage inductance. A lot. And this then permits them to avoid using chokes in the primary winding. The inverters work, well enough to last the warranty period, and then who cares right? that is their attitude.
All the designs I have seen here on The Back Shed have toroids that are wound in a way to minimise leakage inductance and we take great pains to do this with perfectly even windings around the toroid core. Then we NEED the choke and we make sure the choke works well past any expected power levels. Our builds results show very low idle power loss. very low.
Victron's toroids have windings where maybe 1/2 the toroid is uncovered by the outer winding. This makes for large leakage inductance.wronger than a phone book full of wrong phone numbers
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 01:12am 17 Jul 2024
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edit: About 6 reply posts since I started this post.... peak hour :)
I certainly have a lot of these distractions too, I also wondered at just reducing the mains to say 200V, the Nano could do this by changing the (2.8V?) target setting lower, when it has had say some minutes of <300W for instance, so alarm clocks and phone chargers etc can all still keep time and function as normal but if the 300W low limit or whatever limit you choose is exceeded the Nano could immediately go back to normal 230/240Voperation, for when the fridge wants to start.
The reason for identical transformers in the 12KW unit is for dividing the power as equally as possible so they each transform ~6KW. However to extend on Mabs suggestion, if you use the smaller Power board with only 8 FETs such as the Variac power board (plug and play compatible) with a smaller power toroid and combine it with the 16 FET unit with a much bigger toroid for the heavy lifting. That way the smaller power section may be 1-2KW and the other one 3 - 6 KW and with the concept of also being able to reduce the AC voltage by 10 - 40V when it just has idling loads would give the lowest consumption I think can be achieved for this setup.
My advice for Cpocs query about more temperature sensors is to use the 2 on board sensors, say one for each heatsink (which usually run only a few degrees above ambient) and maybe have another dedicated sensor board for the toroid temperatures and toroid fans. This could be easily coupled to the inverter to pause the inverter for excessive temperature/s until they drop to an acceptable level with an Auto restart after. Edited 2024-07-17 11:18 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458
Posted: 01:43am 17 Jul 2024
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Mab, I am curious about your setup. How big is your Powerjack inverter, and how big compared to it are the GTI inverters. Also Are your diversion loads switched in automatically when the PowerJack is likely to be overloaded?
Pete
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 01:48am 17 Jul 2024
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I just checked before posting and quite a few replies are in, but I will still post my thoughts, I'm not trying to contradict anyone on the forum, just my thoughts for my inverter.
So, in "my opinion" there is really no need for the Heat sink temperature input.
Possibility because of fast dead time, symmetrical drive and design of this power board, the FETS produce relatively little heat compared to the older design of inverters.
The temperature is no more that around 5° above ambient in my inverter and no HS fan.
The inverter was close to 4kw for over 2 hours yesterday, it's located inside a warm room at 29°, then FETS reached 32° and sat there - No cooling fan, the 3 series AC output windings on the toroids were slightly warm, core was at 37°, the only heat generated was in the 14 turn input winding and the choke winding cables, chokes felt like "mild" hand warmers - No toriod fan came on.
I plan to use the HS sensor for the second toriod stack (no hardware mods needed), I'm keeping the unused ADC-7 input for measuring the 2nd capacitor bank voltage, allowing my inverter to make sure both capacitor banks are fully charged before enabling the Kilovac.
The thing is, the Nano boards are so low cost, which is why we have one just to do the display, it would be easy to use that for processing other inputs for HS temperatures if you really wanted that and external control, the current DSO sync output pin, could be controlled from the other Nano, it would signal the inverter to ramp down or stop as needed.
That's keeping it "really" simple and not interfering with the current Nano, it allows a fast response to that control input.
At the moment, the controller Nano is just loafing along, the only real limitation is I/O pins.
The auto 6kW - 12kW control should not need to interface to the Nano as it's on the AC side of the toriods - hopefully I have the correct.
The magnetizing power of my 3 stack toriod is around 17 watts DC input from the battery. If you are building an inverter that needs the power of two toriods and power boards, then you must have a big battery bank to run that, an extra 17 to 20 watts?
But as noted some may have long periods of low power or idling, wiseguy address that in the last post I believe. _ Edited 2024-07-17 11:51 by KeepISIt's all too hard. Mike.
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 02:17am 17 Jul 2024
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I did not know the mosfets produced very little heat. I guess I am still thinking in the way of cheap Chinese inverters like the powerjack and Chinese knockoffs. If the design does not need them then they are not needed. Save the I/0 pins for something that is useful and needed. Edited 2024-07-17 12:25 by Cpoc
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 03:54am 17 Jul 2024
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Just keep in mind that this is my experience with my inverter, I've been using this power board for over a year now. It uses a huge heatsink and it turned out to be a complete overkill, a smaller but still large heatsink from old solar inverters will easily handle this, and the heatsink temperature should hardly rise more then 6° above ambient over time.
The temperature sensors on my heatsink are mounted on the FET heat transfer bars, right next to the FETS, these bars connect the FETS to the heat sink, this should be the hottest point in the heatsink to FET thermal coupling. Measuring the body of the FETS as best as I could, indicated a 1° or 2° difference across the insulating medium at high power levels.
IMHO With a good size heatsink with correct thermal coupling it will run relatively cool.
Yes, as I mentioned, use that HS sensor for the second toriod, which is the real heat source and running power limiter, and you could always use an external sensor to monitor heatsinks until you are comfortable with your design at the power levels you want, and confirm for yourself the low heat generation in the heatsink with these power boards and the controller design. _ Edited 2024-07-17 14:03 by KeepISIt's all too hard. Mike.
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 04:04am 17 Jul 2024
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That’s good to know. The design is very well done. With its low cost and ability to swap out components and repair them as well you cannot ask for more. It’s much better than most commercial systems out there. Also the new nano code is very sleek giving you all the feedback info you need you cannot ask for a better design. I am looking forward to my build.
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 06:33am 17 Jul 2024
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I was WRONG with the following:
If you use HI/LO power switching:
You would need to enable the second stage SPWM drive after AC soft start for the second Toroid and subsequent relay close for parallel operation had completed.
In the Nano Controller (as it is now), that control would not need to go to the Nano, you should only need to gate a buffer between the SPWM drive to the second power board, and the buffer could be right at the second power board.
I plan to have the parallel control relay and components, AC filters, current sensors AC voltage feedback, circuit breakers and two full AC function Meters all in a separate enclosure on the wall. This will make servicing simple.
The two Toroid and choke housings will be nice and simple with the bare minimum connections of HI/LO Drives, AC outputs and temperature sensor, the Toriod fans are mounted in a HD trolley base and will blow up through the Toriods when they are placed on that base.
Power stages on top of the Toroids. The Controller, control switches, LEDS and LCD display etc in a housing on the very top.
Now I could be wrong again as this is just evolving, I'm sure Wiseguy is already planning something, but I will use what I have at the moment, I'm happy to mod anything.
Please jump in if I'm missing something or not making any sense at all. _ Edited 2024-07-17 16:35 by KeepISIt's all too hard. Mike.
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 07:23am 17 Jul 2024
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Edit : not sure if you edited your post before I posted but either it changed or my reading skills let me down because now it looks correct.
KeepIS if you carefully read my first post on page 13 of your thread, I explained (or tried to) how to soft start the second transformer from the first transformers 240V output when it was already running normal mains.
I used the example of a globe as an initial current limiter to try to help visualise how we get the second transformer fluxed up with idling current just before we apply the opto/primary excitation for the second power board, so in effect a soft start.
Now I have progressed on from that and plan to use some NTCs to flux up the second transformer with a max worst case single cycle peak current of ~ 11A and reducing each cycle after that.
I am well advanced with a complete design for the second stage auto start, which turns on for greater than 5kW and will stay that way until the load drops to less than 5KW. It uses an AC current sensor, a HEF4538 dual monostable an LM393 and a few other ancillary bits. I expect that it will have teething problems but pretty sure I can beat it into submission. Edited 2024-07-17 17:25 by wiseguyIf at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458
Posted: 07:35am 17 Jul 2024
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I like your idea Mike.
This leaves the main controller as it is.
A software option could be:
Controlling the second parallel inverter (without the pwm) by another nano (a lite version of the allready existing controller for example) wich could have all the extra temperature /current meterings to ensure proper service.
For my personal case I could start making a moderate 4kW nominal inverter as backup.
And then since my ozz inverter holds a real "beast transformer" I could start experimenting with a double powerstage driving it. After each stage I add inductors in series with the transformer. This would be another usecase for the ws concept. Edited 2024-07-17 17:43 by nickskethisniks
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 07:37am 17 Jul 2024
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Wiseguy, great news, yes I understood and read the first two ideas and then the NTCs, so I left that open ended for one of them to be used in the Main AC control housing.
The current sensor and control is what I secretly hoped you were working on, that is a nice clean solution.
I'm allowing plenty of room in the housings for changes and mods.
I love the idea of being able to run at 6kw and 8kw for hours with the Inverter running a few degrees above room temperature, which it does now at 3 to 4kW, just brilliant.
_ Edited 2024-07-17 17:38 by KeepISIt's all too hard. Mike.
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 11:29am 17 Jul 2024
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Is it possible to do a wifi remote real time display from the nano lcd. I was thinking of maybe using a ttl to wifi adapter something like https://www.aliexpress.com/item/32817042658.html?gatewayAdapt=glo2bra and perhaps send the real time data either by MQTT or RESTful api so if you are running say home assistant or SensEsp you can get this data on a remote display. Just an idea. Here is another link to more info https://laborjag.com/venta/arduino/dt-06-ttl-to-wifi/ Edited 2024-07-17 21:42 by Cpoc
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 01:07am 18 Jul 2024
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The simple and lowest cost way is to use a low cost Multi Function WIFI AC meter for AC current, voltage, PF, power and KWh.
If you want the LCD data, the LCD Nano could easily be coded to send the relevant formatted data via a serial to WIFI adapter.
Obviously you can do this many ways, I'm just picking some low cost simple solutions.It's all too hard. Mike.
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 01:22am 18 Jul 2024
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It is not just the AC data current voltage and watts but the other data on the LCD nano. If this can be coded then it would be a great addon feature to add a serial to wifi adapter and display this data on home assistant. It can be done either in MQTT or RESTful api as I believe these two are the most popular protocols that work with home assistant.
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 04:12am 18 Jul 2024
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Understand, that's why I had the options, of course anything is possible, it just depends on finding someone who is familiar with or has the time and inclination to implement the two messaging protocols.
The messaging protocols are supported in Python and many other languages.
The code for the Nano LCD by Poida is freely available on the forum, it's simple and obviously nothing you do the LCD Nano is going to bother the Nano Controller, you could use a different LCD controller if hardware requirements make it easier to use with those protocols.It's all too hard. Mike.
Cpoc Regular Member Joined: 28/05/2024 Location: PortugalPosts: 78
Posted: 06:30am 18 Jul 2024
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No hurry was just asking if it was possible. There is a lot of important info on the nano LCD besides current voltage and watts. Would be nice to see that info on a remote display similar to what Victron does with its gx display. I was thinking the serial to wifi approach was very inexpensive and would be a nice addon feature to have. Home assistant seems to be the most popular display option around it basically works with everything and MQTT and RESTfull api seem the two most popular protocols to work with.
KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1679
Posted: 03:45am 20 Jul 2024
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The AC winding on one Toroid, the other two are almost at this stage, found someone 10 minutes away (business closed a year ago) with new 220A rated Weld Flex cable "very flexible" for the 14 turn drive winding.
Total time so far spent on the 3 toriods is 1 hour. Having surgery on my hand on Tuesday Fortunately I'll have this 2nd three stack transformer ready for winding 14 turns shortly, picking up the cable tomorrow and will run some tests on the spare power board and controller.
I really only have the cases to build and should be able to test a twin power board version shortly after, I hope the hand does not slow me down to much.
Surprised that I got the three Toroids done a lot faster then I remembered taking the last time, then I recalled that I had carefully unwound the 230v AC windings back then, in this strip down, I cut the windings off as I had no use for them
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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Fortunately I'll have this 2nd three stack transformer ready for winding 14 turns shortly, picking up the cable tomorrow and will run some tests on the spare power board and controller.
