Author Topic: 2000w pure sine wave kit. ebay  (Read 1563 times)

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Offline krawczuk

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2000w pure sine wave kit. ebay
« on: November 21, 2016, 08:31:15 PM »
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

Offline Pete

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Re: 2000w pure sine wave kit. ebay
« Reply #1 on: November 22, 2016, 12:45:52 AM »
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

Online oztules

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Re: 2000w pure sine wave kit. ebay
« Reply #2 on: November 22, 2016, 01:15:01 AM »
........ Pete has said it all.

.... not worth the effort.



.............oztules
Flinders Island...... Australia

Offline krawczuk

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Re: 2000w pure sine wave kit. ebay
« Reply #3 on: November 22, 2016, 06:04:18 PM »
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

Online oztules

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Re: 2000w pure sine wave kit. ebay
« Reply #4 on: November 22, 2016, 06:33:30 PM »
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
Flinders Island...... Australia

Offline rossw

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Re: 2000w pure sine wave kit. ebay
« Reply #5 on: November 22, 2016, 10:42:20 PM »
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!

Offline Pete

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Re: 2000w pure sine wave kit. ebay
« Reply #6 on: November 23, 2016, 01:13:34 AM »
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

Offline rossw

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Re: 2000w pure sine wave kit. ebay
« Reply #7 on: November 23, 2016, 02:39:05 AM »
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.

Quote
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.


Offline welshman

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Re: 2000w pure sine wave kit. ebay
« Reply #9 on: November 23, 2016, 04:23:54 AM »
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.

Offline rossw

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Re: 2000w pure sine wave kit. ebay
« Reply #10 on: November 23, 2016, 04:38:19 AM »
this help ?

Thanks, but it's about 5% of the power I need.... and I can be pretty sure they won't stack nicely :(

Offline rossw

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Re: 2000w pure sine wave kit. ebay
« Reply #11 on: November 23, 2016, 04:40:33 AM »
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.

Offline welshman

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Re: 2000w pure sine wave kit. ebay
« Reply #12 on: November 23, 2016, 05:04:32 AM »
rossw: if it was the 1800's id probably have suggested two tiny ac motors connected with a belt ratio to change the frequncy.

Online oztules

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Re: 2000w pure sine wave kit. ebay
« Reply #13 on: November 23, 2016, 12:02:48 PM »
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

ila_rendered



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
Flinders Island...... Australia

Offline rossw

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Re: 2000w pure sine wave kit. ebay
« Reply #14 on: January 04, 2017, 06:24:29 PM »
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!).


Quote
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.

Quote
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?)