Hello out there,
I plan to make the following dc-ac inverter;
1000watts or less,
12vdc car battery will be used;
12dc will be converted to 650vdc peak to peak;
PWM freq. of about 20khz with ferrite or toroid;
650v will be converted to 230vac sq.wave;
sg 3525 will probably be used for pwm;
mofest/ Igbt will be used to convert back to sive wave;
Low pass L-C filter will be used to filter out the harmonics;
Of course there will be a charger for the battery.
I hope to hear from people with more experience on this
design.
SOUNDBAG.
I plan to make the following dc-ac inverter;
1000watts or less,
12vdc car battery will be used;
12dc will be converted to 650vdc peak to peak;
PWM freq. of about 20khz with ferrite or toroid;
650v will be converted to 230vac sq.wave;
sg 3525 will probably be used for pwm;
mofest/ Igbt will be used to convert back to sive wave;
Low pass L-C filter will be used to filter out the harmonics;
Of course there will be a charger for the battery.
I hope to hear from people with more experience on this
design.
SOUNDBAG.
Just thought I'd throw this link out there for ya..
http://www.technology.niagarac.on.ca/people/mcsele/i2k.htm
Good luck!
After looking at that site again,I realised it wasn't a SMPS/PWM type inverter,but it still might be useful?
http://www.technology.niagarac.on.ca/people/mcsele/i2k.htm
Good luck!
After looking at that site again,I realised it wasn't a SMPS/PWM type inverter,but it still might be useful?
pure sine wave inverters.
Thank you,
May I add here now that,
I dont want to use pic microcontroller thing.
I want something simple other people can build.
I want a schematics of less than 1000watts.
I want a circuits that uses mosgate drivers.
What ever happens to the smps gurus?
PLEASE, THE MODERATOR SHOULD CHANGE THE WORD -
"Pure sive inverter" to "PURE SINE WAVE INVERTERS"
of course, this is due to typo-errror.
I heard that some people are using class- d amp topologies to make a dc-ac inverter now, is it true?
soundbag
Thank you,
May I add here now that,
I dont want to use pic microcontroller thing.
I want something simple other people can build.
I want a schematics of less than 1000watts.
I want a circuits that uses mosgate drivers.
What ever happens to the smps gurus?
PLEASE, THE MODERATOR SHOULD CHANGE THE WORD -
"Pure sive inverter" to "PURE SINE WAVE INVERTERS"
of course, this is due to typo-errror.
I heard that some people are using class- d amp topologies to make a dc-ac inverter now, is it true?
soundbag
Re: pure sine wave inverters.
Nevertheless you need a DC power supply with some more volts then the desired coverter output voltage.
Yes, it is. Basically, you could use any Class-D-amplifier, drive it with a sine wave of the desired frequency, provide some amplitude control, and you'll be fine.soundbag said:
Nevertheless you need a DC power supply with some more volts then the desired coverter output voltage.
Sine Wave Inverter
I bought a 600W inverter for £30.00 from Maplin in the UK. It is for a boat; 12v dc in, and 240v ac out. It is unlikely to be a pure sine wave, I haven't 'scoped it so I don't know what the waveform looks like, but this sort of thing is now cheaper to buy than build, like many things nowadays.
It depends on your application how important "pure" is.
Even so, you have 90% of the parts you need for only £30. This could supply the high voltage dc for the sine chopper circuit, with perhaps a little modification; why 650v?
I suggest buying one of these, (Chinese made of course), drawing out its circuit, and seeing how it could be modified to suit your purpose. It would be a lot easier than designing from scratch. SMPS are not easy to design.
edit: The schematic is only part of the design
An interesting thread was started a few days ago about re- engineering stuff for purposes not envisaged by the manufacturer, and this could be one of those projects.
Hope you find this helpful.
I bought a 600W inverter for £30.00 from Maplin in the UK. It is for a boat; 12v dc in, and 240v ac out. It is unlikely to be a pure sine wave, I haven't 'scoped it so I don't know what the waveform looks like, but this sort of thing is now cheaper to buy than build, like many things nowadays.
It depends on your application how important "pure" is.
Even so, you have 90% of the parts you need for only £30. This could supply the high voltage dc for the sine chopper circuit, with perhaps a little modification; why 650v?
I suggest buying one of these, (Chinese made of course), drawing out its circuit, and seeing how it could be modified to suit your purpose. It would be a lot easier than designing from scratch. SMPS are not easy to design.
edit: The schematic is only part of the design
An interesting thread was started a few days ago about re- engineering stuff for purposes not envisaged by the manufacturer, and this could be one of those projects.
Hope you find this helpful.
pure sine wave inverters
650v is the peak to peak for 230vrms when view on a scope, when you switch the power.
The reason for "do it yourself" would have been removed if I have to buy ready made products.
Lets look at it this way;
I wanted to "switched" from my " linear attitude " to making my power with smps, then along the way, class d thing came up, and as I progress the issue of dc-ac inverters/ups came up. The best thing I can do is to follow the thread.
I have not been able to locate the new thread you mention.
Thanks.
___________________________
"measure everything,
dont trust anyman"
650v is the peak to peak for 230vrms when view on a scope, when you switch the power.
The reason for "do it yourself" would have been removed if I have to buy ready made products.
Lets look at it this way;
I wanted to "switched" from my " linear attitude " to making my power with smps, then along the way, class d thing came up, and as I progress the issue of dc-ac inverters/ups came up. The best thing I can do is to follow the thread.
I have not been able to locate the new thread you mention.
Thanks.
___________________________
"measure everything,
dont trust anyman"
It was this thread
650v is the d.c. link voltage for 3phase 415v power inverters, I thought maybe the requirement could be reduced for 230v output.
I've built low power smps, which work well, but I find high power stuff a bit too scary. I have modified one to give different output voltages, and this works very well.
I see many high power types at work, and if something's wrong, they go bang. They are very complex beasts, not something to take on lightly.
Good luck in your quest.
650v is the d.c. link voltage for 3phase 415v power inverters, I thought maybe the requirement could be reduced for 230v output.
I've built low power smps, which work well, but I find high power stuff a bit too scary. I have modified one to give different output voltages, and this works very well.
I see many high power types at work, and if something's wrong, they go bang. They are very complex beasts, not something to take on lightly.
Good luck in your quest.
dc-ac inverter key to energy future
Hi there,
I am still on my project and its getting interesting by the day.
Pls. check www.energychallenge.org for 200l inverter reports.
also look for www.uqm.com 20kw inverters pdf.
I will be back soon.
soundbag
Hi there,
I am still on my project and its getting interesting by the day.
Pls. check www.energychallenge.org for 200l inverter reports.
also look for www.uqm.com 20kw inverters pdf.
I will be back soon.
soundbag
Building this type of inverter ain't easy. Especially when you can buy them off the shelf for less that you can make it for, unless you can get the parts for nothing.
And any mistakes will be costly usually in FETS.
However this is the design principle I suggest.
Convert first the 12v to +/- 350 volts rails using a 3525 with a centre tapped winding on a ferrite core and push-pull mosfet switching. These FETS (or FET groups) will need a current rating of around 200 amps (say 4 x 60volt 50amp FETS per side). This will need feedback to maintain the voltage under load.
Then build what is basically a class D amplifier switching a PWM sinewave with FETS on your +/- 350v rails. This will give you around 230 volts RMS (losses accounted for) into your load. These FETS need to be say 500volt 20amps to allow for surges and stuff and you will only need about one per rail.
Sounds easy....but the quality of components especially the price of good high value and voltage capacitors and the FETS will really be about twice the price of a commercial unit.
If you want to tackle this then I suggest a module at a time. I,e build a simple SMPS using a 3525 first and understand how the whole thing works. Then build a high power version to generate the rails and capacity to feed the class D amp.
There are circuits around for class D amps but you will need to upspec them to handle the power.
Oh ...you will not need to worry about distortion figures.
Good Luck.
And any mistakes will be costly usually in FETS.
However this is the design principle I suggest.
Convert first the 12v to +/- 350 volts rails using a 3525 with a centre tapped winding on a ferrite core and push-pull mosfet switching. These FETS (or FET groups) will need a current rating of around 200 amps (say 4 x 60volt 50amp FETS per side). This will need feedback to maintain the voltage under load.
Then build what is basically a class D amplifier switching a PWM sinewave with FETS on your +/- 350v rails. This will give you around 230 volts RMS (losses accounted for) into your load. These FETS need to be say 500volt 20amps to allow for surges and stuff and you will only need about one per rail.
Sounds easy....but the quality of components especially the price of good high value and voltage capacitors and the FETS will really be about twice the price of a commercial unit.
If you want to tackle this then I suggest a module at a time. I,e build a simple SMPS using a 3525 first and understand how the whole thing works. Then build a high power version to generate the rails and capacity to feed the class D amp.
There are circuits around for class D amps but you will need to upspec them to handle the power.
Oh ...you will not need to worry about distortion figures.
Good Luck.
there was a good inverter article in EW a few months back -- and there is a reason for "approximating" a sine-wave pointed out by the author -- the remote equipment test he had been making had a real hard time digesting a square wave
take a look at Linear Technology's LT3439 switching chip -- you might be able to get some samples sent to Nigeria -- even if you don't use the chip the PDF on this and their other quiet gate drivers should show you how previous designers have approached the problem.
take a look at Linear Technology's LT3439 switching chip -- you might be able to get some samples sent to Nigeria -- even if you don't use the chip the PDF on this and their other quiet gate drivers should show you how previous designers have approached the problem.
My suggestion - buy an off-the-shelf 12V inverter that plugs into a car cigarette lighter, and pull it apart. Steal their design, add some improvements for a higher power output, and call it your own.
As much as you don't want to use PICs, they're probably one of the easiest ways of generating the proper gate drive signals you'll need for the output MOSFETs/IGBTs. The alternative is to create two analog circuits - one producing a 60hz sine wave and one producing a triangle wave at the switching frequency - and compare them.
This isn't that hard to do, anyone who has built a HIP4080 class-D amp is familiar with the method. But going with a microcontroller will be a simpler solution IMO.
All you need to do is select a PIC/AVR/H8/8051/etc which has a couple onboard timers capable of PWM. Store a sine wave cycle (or 1/4 of one) in memory and make the chip fire a new duty cycle value at the timer unit every time a PWM cycle completes. You'll likely need a second timer of some sort in order to provide dead time control, or you can do that with external logic.
The microcontroller outputs (and maybe a bit of external dead-time logic) then drive a pair of gate driver IC's, which in turn drive a pair of gate-drive transformers for your output. Actually, a HIP4080 or HIP4081 could do a wonderful job - it provides both gate drive and dead time control in the same chip.
You could even get creative and use the same microcontroller to generate the gate drive for your 12VDC -> HV DC converter.
As much as you don't want to use PICs, they're probably one of the easiest ways of generating the proper gate drive signals you'll need for the output MOSFETs/IGBTs. The alternative is to create two analog circuits - one producing a 60hz sine wave and one producing a triangle wave at the switching frequency - and compare them.
This isn't that hard to do, anyone who has built a HIP4080 class-D amp is familiar with the method. But going with a microcontroller will be a simpler solution IMO.
All you need to do is select a PIC/AVR/H8/8051/etc which has a couple onboard timers capable of PWM. Store a sine wave cycle (or 1/4 of one) in memory and make the chip fire a new duty cycle value at the timer unit every time a PWM cycle completes. You'll likely need a second timer of some sort in order to provide dead time control, or you can do that with external logic.
The microcontroller outputs (and maybe a bit of external dead-time logic) then drive a pair of gate driver IC's, which in turn drive a pair of gate-drive transformers for your output. Actually, a HIP4080 or HIP4081 could do a wonderful job - it provides both gate drive and dead time control in the same chip.
You could even get creative and use the same microcontroller to generate the gate drive for your 12VDC -> HV DC converter.
Re: pure sine inverter
The inverters I've seen just use a multivibrator to bang a square wave -- so on the transition you have a lot of noise -- the Linear Tech chip I cited drives the gate in a manner which softens the transitions (for want of a better term) -- the Linear Tech application note is useful for its discussion of "prior art"
gmarsh has a good idea in that an off-the-shelf inverter will give you a nice transformer and case and plug-in to the cig lighter -- everything else you throw out!
you don't need a full sine wave, in this application however -- because a full sine wave is going to provide less "on-time" and lower efficiency. you might want to peruse the apnotes on microchip's website.
the Linear Tech chips are included in the parts library of their Switcher CAD software --
soundbag said:
The inverters I've seen just use a multivibrator to bang a square wave -- so on the transition you have a lot of noise -- the Linear Tech chip I cited drives the gate in a manner which softens the transitions (for want of a better term) -- the Linear Tech application note is useful for its discussion of "prior art"
gmarsh has a good idea in that an off-the-shelf inverter will give you a nice transformer and case and plug-in to the cig lighter -- everything else you throw out!
you don't need a full sine wave, in this application however -- because a full sine wave is going to provide less "on-time" and lower efficiency. you might want to peruse the apnotes on microchip's website.
the Linear Tech chips are included in the parts library of their Switcher CAD software --
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.