Power quality, from generator, limiting charge... Solutions?

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Alistair Warburton asked Nov 22, '20

Power quality, from generator, limiting charge... Solutions?

I just closed a thread 'Bat temp OK, charge still limmited...?'

Here which is a preamble to this one.

I have now identified two issues I need to understand / fix

a. The weal AC setting is applying a 2kW charge limit and I dont know why.

b. My generator will not stay connected when weak AC is off and I need to understand specifficall what limits are being checked so I can fix this.

Given that I do not know what aspects of the AC are being checked or what limits are in play I dont know what to try and fix.
I am fairly confident tht the power quality problem is my generator, as opposed to the charger being fessy, but there is some sort of interaction between the two that upsets both.

I have added some chokes to L & N respectively which have helped considderably but not fixed the issue. Adding a comon made choke didnt help.

However I do not know the value of the unts as they are hand wound on scrounged up cores. I do know the value is importent and would be based on what exactly I am trying to fix. Thus not knowing either is a big issue.

Depending on the core periability, unknown, the two I have connected are likely to be between 4 & 12 mH and as they are green epoxy I suspect 12.

I am clearly on the right track but what I have is at best a bodge and at worst could do dammage. I need to find / design a solution propperly and to do that I need to understand precisly what needs fixing.

For now Weak AC will be going back on.

I need to know the switching frequency of the charger.
I need to know what AC waveform artifacts are considdered Poor.
I need to find out / work out what value of choke is likely to work best.
I need to know if a small bypass capacitor, probably between chokes, will help and if so decide on a value.

I am also aware that what I have done may not be a good way to go in the first place and I would be interested in anything anyone can suggest with respect to the problem in general.

Given that there is a charger setting designed to counter poor power quality from generators I am assuming it is relativly common issue.
If the built in solution wasn't hobbling my charge rate I wouldnt be asking about waveforms and chokes...

My goal is to get to the full 70A DC, which is around 3.5kW, and well within what the generator can supply with losses and power factor taken into considderation.

Any and all help or advice would be very much apriciated...

Cheers

Al

Multiplus-II Generator

2

2 |3000

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Paul B commented · Nov 22, 2020 at 12:09 PM

I dont know if you have tried this as its not mentioned in your post

try turning OFF week AC and then turn OFF the UPS setting I find that in a lot of cases this works, and see if this helps.

and or

you also could TRY this and I dont promise anything here as It may not make any difernace. but add the assistant general flag and ignore AC1 input 1 then add a programmable relay set it that if there is voltage on AC1 IN then CLOSE AC1 IN relay, this MAY then stop it dropping out so often. Anyway its worth a try.

good luck in sorting it out

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Alistair Warburton commented · Nov 23, 2020 at 01:26 AM

UPS is off, should have said that sorry...

The assistant thing is an interesting suggestion however if it works, because voltage detection is not he same as whatever syncs the inverter and starts the charger would that not force the unit to deal with poor quality power it should be rejecting?

Its an interesting thought and to be fair it shouldnt work because if it does then bad stuff could occur if arbitrarry closure of the transfer switch is possible.

If you think the transfer switch is still managed, but differently, what do you suspect is different?

Thanks for the comment, I will not be using an assistant to close the transfer without much more info but it is an interesting thought/question.

To be clear, I do not think the issue is the Multi doing something it shouldnt. I suspect that the generator is less than clean and gets far worse when subjcted to the charger as a load.

In industrial applications, VFD's and the like, the harmonics asociated with the bridge switching frequeny can cau significant issues to both the motor and other stuff on the grid near by.
Line ractors and filters, carefully specified as opposd to bodged in, are common place to mitigate the issue....

Hence my bodge :-)

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