Anotherpower.com Forum
Renewable Energy Questions/Discussion => Automation, Controls, Inverters, MPPT, etc => Topic started by: krawczuk on November 21, 2016, 08:31:15 pm
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hi, any body know anything bout these inverter kits from ebay ?
http://www.ebay.com.au/itm/2000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sinewave-Amplifier-Diy-kits-/181957425366?hash=item2a5d81f8d6:g:z1gAAOSwnipWaXUm
bit confused about how to power it ?
says it has two input voltages :
Input voltage: DC380V.
Input voltage: AC16V
anybody know anything bout these kits ?
mark k
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Hi Krawczuk, well reading the very broken english description of the unit, it appears that it is designed to convert modified sine wave inverter outputs into pure sine waveforms.
I am only guessing about the voltages, I would suggest the 16 volt AC is to power the driver chip and circuits and the 380volt would come from the main capacitors on the modified square wave inverter.
There is quite a bit of information on this site about using the 8020 chip as a sine wave inverter driver.
To me it is impossible to tell much from the description on Ebay, I look at the descriptions and if they are indecipherable I steer clear of the item.
This one looks pretty useless from that point of view.
Maybe others such as Oztules will come in with a better idea of what it does.
Cheerio
Pete
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........ Pete has said it all.
.... not worth the effort.
.............oztules
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hi, i did some MORE research , and i THINK , MAYBE its actually a converter not a inverter, it converts a " non sine wave inverter " out put to a pure sine wave. ?
mark k
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The original MSW inverter is used to get the 12vdc upshifted to 380vdc.
This is normally done in multi parallel push pull stage/s...... usually 200-400 watts per parallel unit. A 2kw MSW would than have 5 or even 8 parallel units delivering the 380v dc into a capacitor bank.
The a H bridge switching system of 4 or 8 fets will provide a MSW output of 240vac or whatever they want.
The pictured unit you refer too, is a different H bridge ( programmed for 20khz stepped switching to emulate a true sine wave), takes the place of the H bridge in the original MSW inverter, and so instead makes a pure sine wave, not a modified sine wave... and thats it.... it makes 50hz AC from the DC stored in those 380v caps.
.........oztules
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Oz: or anyone for that matter...
Some of these modules look wonderfully simple and reasonably inexpensive.
Can you think of a simple, easy, cheap way to make a 240V/50Hz input into a 110/120V 60Hz sinewave output at up to about 100W maximum?
My wife got a piece of equipment - only cost $300 - but it's designed for the US market. Unfortunately, its speed (which is critical) is based on a 2-pole induction motor, and it simply will not get up to speed on a 50Hz supply. It uses phase control (series triac), a microprocessor and an optical tacho on the motor shaft.
I don't want to spend more than the darn thing is worth, but it would be really nice to get it working properly rather than the stupidly expensive, bulky and ugly temporary fix (using one phase of a 1HP VFD). I figure 50-80W would do, but 100W would be safe. Any thoughts? It also would want to be sufficiently small that it could fit inside the existing device. There's a bit of room in there, but it's not all in one spot!
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Ross, I guess it is too difficult to just change the motor in the machine over to a 240 volt 50 hz job?
Other than that I guess a small 110volt 60 hz inverter running of a battery is the cheapest way I can think of.
There are other ways that the technologically minded person with unlimited time and patience could use such as building a small rotary converter but the motor change or inverter would be my way.
Pete
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Ross, I guess it is too difficult to just change the motor in the machine over to a 240 volt 50 hz job?
A 50Hz non-brushed motor simply won't go fast enough.
A 50Hz/2 pole motor can make 3,000 RPM with zero slip. Say 2850 RPM with enough slip to work properly.
A 60Hz/2 pole motor will do 3,600 RPM with no slip, or around 3300+ RPM with.
In order to make 3200 RPM (required), a 50Hz brushless, non-geared motor simply cannot make it. Period.
Other than that I guess a small 110volt 60 hz inverter running of a battery is the cheapest way I can think of.
All the inexpensive, low-powered ones I've seen are MSW, and phase control doesn't work very well. It's also pretty nasty on a precision motor thats in this thing. And a battery is going to have to be pretty big to run this thing for 3 or 4 hours. (that could be getting on to close to 400WH)
I initially read this thread as a 200W inverter, not 2000W, hence my interest.
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this help ?
https://www.alibaba.com/product-detail/PA-B-Series-3-6W-ac_60095845878.html?s=p
https://www.alibaba.com/showroom/220v-50hz-110v-60hz-converter.html
mark k
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rossw: single phase frequency drive inverter to make the 60hz and a voltage stepdown transformer 230/110 to drive it as frequency inverters input and output voltage are analogous. this is the only way i can see of achieving a mains style pure sine.
however to make something with a truly reliable sine wave from scratch you would be halfway to building your own decent inverter. even if you scale it down to 100w application. inverter driver board, transformer etc.
at that point you might well be cheaper buying a 240ac to 12 dc transformer wall plug in type and a good pure sine wave low power 12dc to 120ac inverter.
edit maybe i was wrong about the voltage analogous part
this device http://www.ebay.co.uk/itm/Yaskawa-0-1kW-Inverter-VS-mini-J7-CIMR-J7AA20P1-AC-Drive-200V-3-Phase-/111991805521?hash=item1a133b5651:g:nloAAOSw2x1XMLYD seems to be able to scale the output voltage from 0 to 230. so the stepdown wouldnt be needed, but again i dont see a way to scale this down to fit inside the device.
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this help ?
Thanks, but it's about 5% of the power I need.... and I can be pretty sure they won't stack nicely :(
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rossw: single phase frequency drive inverter to make the 60hz and a voltage stepdown transformer 230/110 to drive it as frequency inverters input and output voltage are analogous. this is the only way i can see of achieving a mains style pure sine.
The VFD I am currently using lets me set the voltage (largely independent of input volts), so no transformer required.
It's still expensive, inefficient and bulky.
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rossw: if it was the 1800's id probably have suggested two tiny ac motors connected with a belt ratio to change the frequncy.
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Yes. It can be simple and cheap.
There are kits out there for 30-60 dollars that are egs002 based, with their circuit board supporting 1000-2000w.
That kit at the start of this post will do fine...
http://www.ebay.com.au/itm/2000W-Pure-Sine-Wave-Inverter-Power-Board-Post-Sinewave-Amplifier-Diy-kits-/181957425366?hash=item2a5d81f8d6:g:z1gAAOSwnipWaXUm
[attachimg=1]
Use the mains for the 380vdc ( 340v) ( it does not care what volts it is really). then simply choose the 60hz option, you can dial up any output voltage you care to use. The egs002 does not see anything unless you tell it. so you have the VFB set so it outputs 110v, and the jumpers set for 60hz
You would need the kit, and rectifier and looks like the filter caps are there already ( 450v 105c types). Should be perfect for your purposes. Will cover start up too of the induction motor I would reliably expect.
You can easily choose the variable frequency jumper, and use it for speed control without the phase chopper in the unit if you want perfect speed control of the induction motor. less noisy and clean operation and better torque. "It uses phase control (series triac), a microprocessor and an optical tacho on the motor shaft." maybe an opto to the board will do for the control signal for frequency?.. or just leave well enough alone.
I guess that would make it a universal supply, with voltage settable from very low to 230vac perhaps, and frequency up to 400hz I think.
.........oztules
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Yes. It can be simple and cheap.
There are kits out there for 30-60 dollars that are egs002 based, with their circuit board supporting 1000-2000w.
That kit at the start of this post will do fine...
Back to this project after the madness of the last month or so.
My EGS002-based inverter (1000W, but basically just the 2KW without half the fets!).
Use the mains for the 380vdc ( 340v) ( it does not care what volts it is really). then simply choose the 60hz option, you can dial up any output voltage you care to use. The egs002 does not see anything unless you tell it. so you have the VFB set so it outputs 110v, and the jumpers set for 60hz
Done.
You would need the kit, and rectifier and looks like the filter caps are there already ( 450v 105c types). Should be perfect for your purposes. Will cover start up too of the induction motor I would reliably expect.
It does.
So having return the original internal transformer to the 110V job, sealed the box back up... connected the new 240V/50Hz to 110V/60Hz "converter", powered up... and the centrifuge is humming like it normally doesn't. Damnit, the motor is running flat out and the tacho says 3300 RPM!
.... but the lid is open and it shouldn't be running at all!
The circuit for the motor is dead simple (scary simple!).
Mains in. Neutral in goes straight to one side of the motor.
Line (Active) in goes to one side of a triac, out the triac straight to the other side of the motor.
Triac has a basic snubber across it, 10nF + 39R in series.
Triac triggered by 220R in series with an opto-diac (MOC3052) between active and gate.
Scary that the interlock isn't actually in the supply line to the motor...
Anyhow, despite the output "looking pretty good" on the CRO (via an isolating transformer), there is obviously enough high-frequency transient component left to trigger the triac (high dv/dt I guess?).
I whacked a 10uF/400V cap in parallel across the inverter output but it made no difference :(
I didn't want to have to go to the complexity of building a fancy lowpass filter. Do you think increasing the snubber cap is practical/sufficient, or am I going to need to make a proper filter (suggestions of how much inductance I might need? Do you have a preferred filter type for this application?)
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Interesting.... we have no such problem driving phase switching gear here.... heat guns etc.
I guess the 20khz pwm is switching 380v, and so the shaping cap was supposed to damp the 380 peaks and bring it to a sine wave. You have increased that to no avail.... hmmm.
Maybe the scr is a sensitive gate type, and needs some damping between the gate and cathode to muffle the noise on the inputs.
I use standard emi filters from other gear ( GTI's ) for the filter, and this solves the problem for front loader washing machines..... maybe this is your best bet.
Without the emi filters, the front loaders have trouble not with the normal washing cycles, where it uses the tacho as the speed reference, but the start of the spin cycle, where it measures the current draw of the scr to determine the state of cloths weight against rotation in degrees to see how the load is spread... ie do we spin hard yet, or do we need to mess about and continue to spread the cloths more evenly.
The 6kw selectronic up the hill has that trouble too ( or rather the Asko washer has that problem with the selectronic, but not the power jack conversion)... so that may help with your musings.
Impressed you have given it a try :).... now fix up the old selectronic next for a spare.
EMI filters should be all over the place, in psu's, and most consumer stuff now.... fridges, dryers, etc etc.
............oztules
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Interesting.... we have no such problem driving phase switching gear here.... heat guns etc.
I'd expect more problems under the lightest loads - this thing has a motor that draws around 60W.
I guess the 20khz pwm is switching 380v, and so the shaping cap was supposed to damp the 380 peaks and bring it to a sine wave. You have increased that to no avail.... hmmm.
That was my suspicion too, hence the extra cap.
Maybe the scr is a sensitive gate type, and needs some damping between the gate and cathode to muffle the noise on the inputs.
Try a no-gate unit! Damn triac was shorted A1-A2. Have replaced with something out of the junk box, and it's working like a beaut now.
Impressed you have given it a try :).... now fix up the old selectronic next for a spare.
Hah! It was only your suggestion and supreme confidence that encouraged me :)
The old 5KW unit isn't a contender for this... it weighs 100Kg for a start!
The centrifuge needs to be portable - we carry it around to wherever we're doing our tests, so I wanted something small and light enough to bolt (preferably) inside the centrifuge. This board might just make it, I'll have to make some mounts for it. Otherwise, it'll have to go in a box screwed to the back, or perhaps as a "stand-alone" 110V/60Hz box. I must say though, that I'm sufficiently impressed with the way it works, I might get another one as a spare.
Cheers, and thanks!
R.
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Chuckle, chuckle.... no I meant fix the selectronic as a back up house inverter using the 8010 chip, or even the egs002 if your a bit slack.... shame to have a 100kg boat anchor, when it could be a super- star inverter again.
It's got a box and transformer... and thats enough to get her going again.
...........oztules
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Well, it's done and dusted.
The only downside with that board is that it needs not only 380V DC, but *ALSO* 16V AC or at least 14.5V DC, to run the logic.
I have any number of little 5V, 9V or 12V plugpacks, but nothing around 15V. I was testing it all with a 24V/2A plugpack, but that was not going to be very convenient in the devices final application.
So... I grabbed one of the hundred odd 9V plugpacks in my stock. A quick squiz and it has a TL431A driving the feedback opto. This has a reference voltage of 2.5V, and on the PCB it had a 27K resistor to +V and a 9K7 to Gnd. Didn't take long to figure out that replacing the 9K7 with a 5K6 and I'd have a nice 14.5V - and it worked great.
Ripped the board out, mounted it on the inverter board, bypassed the current limiting on the mains side, stole the SMPS bridge to drive the inverter... and we're done!
(http://house.albury.net.au/06jan2017/IMG_2723.jpg)
(http://house.albury.net.au/06jan2017/IMG_2722.jpg)
Put it all back together and it runs smooth, quiet and cool. Oh, and at full speed!
Thanks everyone for your contributions and encouragement!
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Nice implement Ross, indeed.
Now that I've had a chance to look this over closer, only one additional thing comes to mind for the "filter" question for smoothing...
The output filtration may be better looked at in terms of a "freewheeling buck converter" of sorts... there's LC action yes, but you (or anyone running across this at a later time) might find the answer to the choppy vs smoother output amongst the "continuous vs discontinuous" inductor operation associated with buck and boost converters.
In a sense, that's essentially what's taking place. When the load is sufficiently mismatched, not enough (or too much) current flows in the inductor at the output, leading to either something resembling discontinuous mode in a converter (which as you found, the cap only plays a "niche" role in), or in the case of more current than the ideal, saturation, leading to ripple caused by the core going non-linear. Tinkering with the value of the inductor will have a much more profound effect on the "quality" of the output (which of course in the case of your motor drive or other "dedicated load", can be dialed right on in.)
This isn't to say ignore the cap, it just doesn't play the role that it immediately might seem to play in the big picture.
On a related note, if you look at the front end of an active PFC circuit for switching supplies, you will spot the immediate resemblance to the final components in a PWM/PSW inverter filter... the only real difference, is (nearly literally), everything is completely reversed. The mylar cap plays a key role there just as in the inverter, and is appropriately referred to in many cases as the "resonant cap" - bigger or smaller upsets the balance of the LC and the inductor needs to be adjusted as well to suit.
Only other thing, which I'm sure goes without saying, but maybe not so much for those just starting to get their feet wet in this stuff, is of course all of this is very heavily intertwined with the base switching frequency for the PWM that ultimately creates the sine...
Ain't SMPS so much more fun than boring old iron laminate EI, a simple bridge, and electrolytics that easily found new life simply as paperweights? Or "Power Hartley's" that make better heaters than inversion circuitry? ;D 8)
Cool stuff.
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Thanks Steve.
It's really not as bad output as my earlier post implied. When I first fired it up, I hooked my DSO on (but as it's mains operated and almost certainly grounded, and since the inverter is full-wave rectified mains, I figured it wasn't a bright idea to just clip the CRO straight on the output!).
Here is the output, with the physically smallest transformer I could find - ie, the least iron and windings to filter out the crud.
(http://house.albury.net.au/06jan2017/IMG_2719.jpg)
(Ignore the voltage, it's not representative of anything, the waveform alone, and it's frequency, is all that this pic was to show)
The failed Triac was (as I have now determined) as result of the failure of the autotransformer in the penultimate "work-around" (trying to give the motor only 110V from a 240V supply, and the point I gave up with such folly).
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Steve
"This isn't to say ignore the cap, it just doesn't play the role that it immediately might seem to play in the big picture."
No..... the cap in question Ross fiddled with does not work as you think. It is the shaping capacitor, and without it, the wave is unrecognizable, and the VFB won't even work, and will swing to PWM max.. and then die. It cannot work with out it.
The noise filtering is not critical, and anything will work to some extent.
..............oztules
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Oz -
Oh, no I agree it must be present. Shaping, resonant, similar of not outright identical concepts behind the names.
What I was mostly getting at is it only has so much effect because it needs to be within a relatively narrow window of values to do it's job correctly.
The inductor has more room for playing with the value because it's catching and converting the PWM, with the cap being part B of that conversion (representing the low impedance that the inductor needs to do /it's/ job correctly.
This was why I pointed to the inductor as the more flexible component in terms of making changes. The cap has 2 jobs to do, "terminating" the inductor, and shaping the sine. If it's too big, distortions from excessive energy storage... too small, sine gets spikey because it isn't able to hold on long enough between pulses. All the inductor has to do is dv/dt control by virtue of ELI, hence the "buck converter" reference, into the cap where ICE finishes the job.
They're both critical components, just one has a bit more wiggle room for tweaking than the other for a dedicated supply such as the centrifuge.
That said, if that's the wave you've got Ross, I'm not seeing anything to bother with any tweaking ;)
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Happy 2017 kids !
At Trace Engineering in the late 1990s, one of the engineers (Milt Rice RIP) was working on
a product called the "Co Sine" that was basically one of these deals that took the rectified
output of a modified-square wave inverter and turned it into a sine-wave add on.
"ALMOST" became a product but it cost too much back then.
boB
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Are you rectifiying the mains input before the board or is there any need?
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Yes, I have full-wave rectification of the mains before the board, and yes it is necessary!
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Thanks, wasn't sure if it was included on the board or not.
Any idea if there is any headroom available above the 380V level?
If it could run up to say 400V, it could be an option for running AC loads direct from the battery pack of a Nissan Leaf for example, could be useful!
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OK, Oztules (particularly) - but anyone else with any bright ideas, I'm looking for guidance!
After the great success of my previous centrifuge conversion with one of the you-beaut HVDC input pure sine inverters, I thought I'd do the other one. Ordered the same inverter kit from the same guy....
... only it turned up different (of course! Why wouldn't it?)
So I assembled it anyway, it has an extra output filter, slightly different input requirements (has 15V reg rather than 12V) but otherwise superficially looks the same.
(http://house.albury.net.au/24feb2017/IMG_2758.jpg)
The only perhaps "notable" omission is that it only has a single 2.2uF/630V cap in the primary filter.
The output - measured through an isolating transformer (which should clean it up a bit) looks bloody horrible:
(http://house.albury.net.au/28feb2017/IMG_2774.jpg)
The "flat-spotting" is not crushing from insufficient DC - if I adjust the voltage set pot, the waveform retains the same shape, while the output voltage goes up and up and up... (it's backed off to 110V here, but it keeps that waveform the same if I take it up to 180 or 200V - so it's intrinsic)
The output also has all manner of spikes and spurious, the frequency drifts all over the place. 60Hz +/- 1Hz.
Since it's driving a computerised phase-control speed controller, the results are... well, it's unusable.
I don't expect any sort of help from the vendor - there's absolutely no controls other than the voltage adjust, I'm at something of a loss where to look at. Ideas??
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There may be a few ways to kill a wave like that... but the changing HZ and the glitchiness would suggest a lousy board... perhaps get another egs002 for ten dollars and try that. ( or steal the one from the working board you have already) The fet board should not cause that.... more likely from the driver chips being "loose" or an earthing problem on the 002 board....
In short another 002 should solve it I would expect...... or you could try to find out if the caps around the 2110's are secure, as it looks like the driver gives up at some point.
..........oztules