Sine wave power inverter

[psdayama]

Hi Saugata,
Its OK to be late than never. I think U should stop the work on high frequency
as there are more complcations. Instead I suggest that whats Ur code for
current work is alright.
I am planning to make inverter with Half Bridge
output which is direct to Load and not thru transformer. Problem is everybody is inverting at low frequency of 50Hz from battery. And use same
transformer for charging battery when on mains.
If we make high frequency >40 Khz inverter with
square wave and output is rectified and made high voltage DC then with dual supplies (+/-) we can use IGBT/MOSFET half bridge to drive sinwave output
directly without transformer. This will save the output transformer cost and ferrite transformer would cost hardly 100/-. Also for charging battery same type SMPS circuit can be used and its wattage can be max 120W which would cost hardly 200/-.(Old PC SMPS 250W are available for 150/- in market)
I am still designing the circuit. I will post the block diagram here as soon as
it is ready.
When you are working with this type circuit U can have slightly expensive
circuit which doesn't require a relay -sugar cube or any type as U are just switching DC sources with help of diodes and they are very fast!
Basic plan is
MAINS POWER---|----->SMPS WITH CHARGE CONTROL--> BATTERY->-|
|_____>RECTIFIER --->|<RECTIFIER--<SQR.INVERTOR<|
|
50HZ PWM INVERTOR WITH HALF BRIDGE OUTPUT
|
LOAD WITH SMALL FILTER

This ckt will work like true online UPS still expensive just as much as ordinary
invertors.But U can have Ur DSP alright and also PICs other a/d lines can be used for battery charge management as well!
For cheaper type the Mains rectifier for dual supply can be ommited and
instead sugar cube relay used for switching outputs. Half wave +/- rectifier
requires costly HV elcos.
For good ferrites ask for dealer of Cosmo Ferrites. U check their list on web page. There is another manufacture Hinodaya.
I won't be attending M'Chip Masters course as I am just beginer in this field but not to programming. May be I will attend next time when I hope to get some nuances and I am working on Transformer Ratio test set(comparator
type) and want to use PIC for advanced features.So I think that I will also be
familiar with PICBASIC then.
Wish all the best for conference.My place is abt 2hrs from Lonavala
regards,
psdayama

[sougata]

Hi Dayama,

What you are proposing is a dual conversion design. When you have a battery bank of greater voltage it makes sense other wise for a 12/24 volt system consider this.

1. The Primary current will in the order of 50 AMPs so it is necessary to use copper bands for the primary windings.

2. Frequency has to be kept high (ferrites) consider the switching losses of the primary MOSFETs

3. You have two different switching stage so a single PIC may complicate your programming issues.Of course you can use a ready made SMPS controller like the SG3525 but then this forum may not be the right place to discuss.

4. Microchip has a very good appnote on such type of design.

If you are using PBP then this forum will help you out in solving problems.

One of my laboratory power supplies runs on a PIC for a Buck regulator.

We get only a limited supply (not all models) of cosmo ferrites so it is beyond my scope of experiment. However I would definately like to meet you while I am in Mumbai.Send me a private email if you are interested.

Regards

Sougata

[psdayama]

Dear Saugata,
please read my comments pointwise:

Hi Dayama,

What you are proposing is a dual conversion design. When you have a battery bank of greater voltage it makes sense other wise for a 12/24 volt system consider this.
1. The Primary current will in the order of 50 AMPs so it is necessary to use copper bands for the primary windings.

When one is making Inverter/UPS then the transformer and MOSFETS
have to handle this currents and I have seen atleast 3in parallel to do this.
I think It is OK for 500VA and for 1KVA one has to use 24V battery for same
purpose. Higher rated systems are using batteries 48V or even 110V!!!

2. Frequency has to be kept high (ferrites) consider the switching losses of the primary MOSFETs.

Frequency has been optimised to 40-60KHz for considering this aspect.
I would like to use more than 100Khz if possible but then MOSFETs would be
beyond reach.

3. You have two different switching stage so a single PIC may complicate your programming issues.Of course you can use a ready made SMPS controller like the SG3525 but then this forum may not be the right place to discuss.

My design has 3 switching stages. a)First for conversion to 12V from 230V(SMPS), second a simple Inverter to convert 12Vdc to 300V dc dual supply and lastly the Sinewave converter with half bridge for direct output.
SMPS is based on SG3525 and dc to dc also same but they can have analog
control inputs with additional PWM from Microchip instead of DAC.The last converter is entirely based on Microchip and same chip can used for other indication or control functions. One has to consider the entire system development and how to make optimum use of available resources. It is just
not possible to use one PIC for all functions reqd.

4. Microchip has a very good appnote on such type of design.

Please do send link for that design.

5.If you are using PBP then this forum will help you out in solving problems.

Im not aware of PBP. I am doing programming in Assembly and use a
program to convert it in code.

6.One of my laboratory power supplies runs on a PIC for a Buck regulator.

Im very interested know about it.

7.We get only a limited supply (not all models) of cosmo ferrites so it is beyond my scope of experiment. However I would definately like to meet you while I am in Mumbai.Send me a private email if you are interested.

Regards

Sougata

Please visit cosmo ferrite website. They have dealers all over India and
Kolkata must be having some. If U want some hard to get size then I can
help. But for regular supplies the company will gleadly contact U.
I think I have missed Ur reply due to incorrect setting of intimation. Im
sending U private email for details.
Thanks,
psdayama

[dknagare]

Dear Saugata,
please read my comments pointwise:




When one is making Inverter/UPS then the transformer and MOSFETS
have to handle this currents and I have seen atleast 3in parallel to do this.
I think It is OK for 500VA and for 1KVA one has to use 24V battery for same
purpose. Higher rated systems are using batteries 48V or even 110V!!!


Frequency has been optimised to 40-60KHz for considering this aspect.
I would like to use more than 100Khz if possible but then MOSFETs would be
beyond reach.


My design has 3 switching stages. a)First for conversion to 12V from 230V(SMPS), second a simple Inverter to convert 12Vdc to 300V dc dual supply and lastly the Sinewave converter with half bridge for direct output.
SMPS is based on SG3525 and dc to dc also same but they can have analog
control inputs with additional PWM from Microchip instead of DAC.The last converter is entirely based on Microchip and same chip can used for other indication or control functions. One has to consider the entire system development and how to make optimum use of available resources. It is just
not possible to use one PIC for all functions reqd.



Please do send link for that design.



Im not aware of PBP. I am doing programming in Assembly and use a
program to convert it in code.


Im very interested know about it.


Please visit cosmo ferrite website. They have dealers all over India and
Kolkata must be having some. If U want some hard to get size then I can
help. But for regular supplies the company will gleadly contact U.
I think I have missed Ur reply due to incorrect setting of intimation. Im
sending U private email for details.
Thanks,
psdayama

I have tried 3 to 4 designs of this type of technology. About 5 years ago i used SG3525 @ 50KHz for battery boost 12VDC to 320VDC and then chopped with squarewave 50 Hz using again SG3525. I have used full bridge for DC to AC conversion. The result is very satisfactorily over 5 Years of cont. use now I am trying to make it sinewave within a month or so it will be ready.

[sougata]

Hi,

I originally posted this thread and I would like to know the details what you are actually trying to do.

[dknagare]

Hi,

I have already tried transformerless( only small ferrite core of EE65X13) design upto 1000W but output was squarewave. Now I will use SPWM signal to convert DC to AC. In this type it easily possible to make 3Phase output without much circuit.

My main aim is to make sinewave inverter without using bulky iron core. I will upload some details very soon.

[psdayama]

Hi,

I have already tried transformerless( only small ferrite core of EE65X13) design upto 1000W but output was squarewave. Now I will use SPWM signal to convert DC to AC. In this type it easily possible to make 3Phase output without much circuit.

My main aim is to make sinewave inverter without using bulky iron core. I will upload some details very soon.

Thanks a lot for information. For long time nobody posted and Saugata is
busy with his own projects. I also came across one commercial model which
didn't have any bulky transformer but only small ferrite ones like in smps.
I think I sent my block diagram to Saugata. I have changed OS in my PC and
it is difficult to locate it but I will get and put it here.
My idea was to have inverter with output switched by fast relay for crossover. Also if we don't use relay and instead use directly take out output
from inverter and meanwhile have heavyduty charger, we get cheapest
online UPS. For this there can't be output transformer and so output has to be HalfBridge type with centre tapped power supply. To get this advantage
we have to put premium on the Mosfet/IGBT voltage.(Require withstand voltage atleast 800 to 1000V) but that is better than some 10Kg transformer
for 1000W type and also price about 1000-1200/-.
I am also having one inverter with high frequency chopping but its output is
50Hz and so transfomer is very bulky.
Now I pray that sooner or later Saugata will tell us about new design !!!

[Navneet Vinaik]

Hi Everyone,

I have just started work on sinewave inverter using Metal transformer, using PIC microcontroller.
Can anyone provide me some tips.

[sayzer]

Navneet,

That is something that a lot of people are asking for.

If you find code examples pls remember to come back here and post.

--------------------------------

[mat janssen]

I made for an old friend a chip where he could select one of 16 sinewave frequencies to open a relay in a repeater (for transmitting)
Here is a part of the programm only one frequency (50Hz) is there now.
the rest is not important.
It gives the 50 Hz in 200 parts of pwm.
When putting a lowpass filter after the output. The sinewave is back.
Regards,
Mat

[psdayama]

Hi Everyone,

I have just started work on sinewave inverter using Metal transformer, using PIC microcontroller.
Can anyone provide me some tips.

Hi Navneet,
it seems that U are trying to reinvent wheel!
Please go thru the whole thread. In last post I mentioned one article
which is evaluation of PWM sinewave inverter. Also there has been discussion
on disadvantages of metal txr. If U can design proper program for sinewave
PWM then U can utilise ferrite txrs with switching frequency 25KHz and above.
The cost & weight of metal txr is major problem.
Rest wish U best of luck!

[Navneet Vinaik]

Thanks Psdayama, Mat and Sayzer.

I have downloaded the code and paper.
Can anyone guide me hw to calculate the pulse width's effectively?

[pramodsinha]

hi, everybody!
In the market lots of sine wave inverter available in pic 16f72 they are using software pwm not hardware pwm in the entire forum no body has discuss about software pwm , as 16f72 is very cheap and easily available.
I think we should explore about generating software pwm to create sine wave in a bridge configuration, I am trying to develope it and hope it will be successful in this month after finishing i will be able to put some light on it.
thanks

[sougata]

Hi,

My original design was based on a 18F452. Using both of the hardware PWMs and a sine weighted lookup table to modulate the PWMs at regular intervals. The interrupt routine also triggers an ADC to correct distortion on the output. So the ADC was sampled after every PWM steps. I found that the internal ADC was not giving me good results so used an external one. Now I realize that I actually complicated my design.



After the Master's Conference in Gurgaon India me and Pramod would be jointly working on a software based PWM sine wave UPS/Inverter this month. It is again a commercial project but we can sure shed some light and guide people by at least suggesting a way. A normal home UPS/Inverter does not need (at least here) a distortion free clean Sinewave. So we are restricting ourselves to the following criteria.

1. Low Cost
2. Low component count
3. Decent sinewave generation with only average variation for voltage regulation and no THD management.

Hope we successfully complete the same. We will get back here, since this is the place where we met.

[karthickefy]

HI sougata

can you please send me the sourcecode for pic 16f72 based inverter. please find the attachment for 16f72 based inverter circuit.
i'm waiting for your valuable reply.

Thanks and regards,
Karthick
[email protected]

[karthickefy]

HI sougata

can you please send me the sourcecode for pic 16f72 based inverter. please find the attachment for 16f72 based inverter circuit.
i'm waiting for your valuable reply.

Thanks and regards,
Karthick
[email protected]

[pksinha]

Source code is property of jetmark technology,delhi, of above schematic available on commercial terms.
Best regards
pksinha

[babalola]

Hi Das,
What a long time! thanks that the forum is back again, we cannot wait too long to see your inverter design for all.
I think this time around it will afford all of us opportunity to explore every aspect of digital sine wave inverter design.
Thanks for your effort so far,
Regards,
Babalola

[TahmidMahbub]

Regarding sine wave generation and sinusoidal pulse width modulation, I have written quite a few articles and have posted them on my blog. You can find them here:


Generation and Implementation of Sine Wave Table
http://tahmidmc.blogspot.com/2011/01...n-of-sine.html

Smart Sine - Software to generate sine table
http://tahmidmc.blogspot.com/2012/10...rate-sine.html

Generation of sine wave using SPWM in PIC16F684
http://tahmidmc.blogspot.com/2012/10...pwm-in_10.html

600W 50Hz sine wave inverter test circuit
http://tahmidmc.blogspot.com/2012/10...rter-test.html

Feedback in sine wave inverter (PIC16F series based)
http://tahmidmc.blogspot.com/2012/11...er-pic16f.html

Demystifying The Use of Table Pointer in SPWM - Application in Sine Wave Inverter
http://tahmidmc.blogspot.com/2013/02...ointer-in.html

Sine Wave Generation without ECCP - Using single CCP Module of PIC16F877A
http://tahmidmc.blogspot.com/2013/02...t-eccp_16.html

Sine Wave Generation with "Fast PWM Mode" of AVR - using ATmega16
http://tahmidmc.blogspot.com/2013/02...mode_2525.html

I hope everyone finds these articles/tutorials helpful.

Regards,
Tahmid.

[iw2fvo]

Thanks a lot for this post:
this is the most interesting article I have found in this forum.
There are a lot of things to learn.
congratulation to Tahmid.
Regards,
Ambrogio
IW2FVO

[TahmidMahbub]

Thanks a lot for this post:
this is the most interesting article I have found in this forum.
There are a lot of things to learn.
congratulation to Tahmid.
Regards,
Ambrogio
IW2FVO

Thanks.

Tahmid, I've tried to access those files but it seems the file path is unavailable. can you please refresh the link

The links should be fine. They're working fine for me. Please try again.

[wire042]

Tahmid, I've tried to access those files but it seems the file path is unavailable. can you please refresh the link

[wire042]

I have built this inverter but am having some issues with the charging, when I put on the mains my FETs get burnt especially the 2 Low side.
Can some one give me solution to this problem

[babalola]

can you post the aspect of your code that deal with the charging?. here you are talking about syncronouse boost charging when you are using the 2 lower fet to efect the charging. in this case the 6v at the secondary of the same power tansformer is boosted to about 14v to cgarge the battery.note however that at this time of cgarging the upper 2 fets must be switched off then pass you PWModulated signal of a particular duty cycle to drive the lower mosfet. remember equally you are using the leakage inductance of the power transformer for the inductor part of a typical boost converter.
i hope this help,
regards,
babalola.

[sougata]

Hi,
I feel sorry that I am not being able to support this thread as I should and could not complete the conversion of my SMD design to Hobbyist version. (I wish though) Here are some quick tips that may help you babalola:

Synchronous Rectification Deals with Switching on the upper FETs on a per cycle,phase basis so that the rectifier efficiency is best while charging, where the Body Diode is superseded by the RDSon of the MOSFET. For the upper one this may sound simple if you are sensing the input AC and know the Transformer connected as ( Primary Start/Finish vs Secondary Start/Finish, My Pro Design detects it) but for the lower one it gets tricky.

So lets forget Synchronous for now and let the upper MOSFETs behave just like diodes.

Apply PWM to both the Lower MOSFETs simultaneously but only in the middle of a single cycle, with upper limited duty cycle.
To experiment what is the limit with your transformer and profile entire system.
Have a load () connected to the Bridge +DC- and ensure Caps in order of 10000uF
Run a slow loop to increase the PWM (till you fry your MOS )
Idea is to figure out if you are actually achieving any boost

And Tahmid thanks for the great post. I wish I could actually spend sometime giving back to the community for which I am whatever I am today. But I personally would not buy the idea of, a set of different lookup tables for voltage regulation. You can have a 8x8 unsigned multiply within 54uS as stated by Darrel somewhere else and an unrolled Bit tested, rolling multiply takes about 42-44uS to call from PBP. For a proportional control and tricky retention of portion's of older error (I call it pseudo I, cause a software automatically introduces the integration Time) at least a PI system can be designed.

What I have learned from experience is that sometimes it is the Hardware that is crap than my own code (Loads of Crap ) which is to be blamed. Post a schema if possible.

Something to read : http://www.researchgate.net/publicat...fe3d4e9275.pdf

Thanks to all
Regards
Sougata

[barkerben]

I made a 24v, 250W Quasi sine wave inverter using a basic PIC (can't remember the exact details) a couple of years back.

It used quasi sine rather than full sine - in other words, a square wave with dead time. Having said that, regulation was less than 10% at full load, and efficiency was over 95%. Quite good fun really...

[psdayama]

I made a 24v, 250W Quasi sine wave inverter using a basic PIC (can't remember the exact details) a couple of years back.

It used quasi sine rather than full sine - in other words, a square wave with dead time. Having said that, regulation was less than 10% at full load, and efficiency was over 95%. Quite good fun really...

Quasi SineWave shouldn't require PIC !
Also regulation seems to poor as even 1% easily achievable. May be U have
some special functions so U are welcome to elaborate.
psdayama

[barkerben]

I think we used a PIC for two rasons. Firstly, we wanted the option of going to full sine wave. Secondly, we could eliminate regulation by dynamically changing the deadtime in the quasis sine wave. The 10% (I think it was 10% - lng time ago now) was without any feedback, when running at full load (250W). The PIC was also useful at startup.

Ben

[psdayama]

Hi barkerben !
thanks. It was just curiosity as just few months ago Electronics For You (EFY)
India magazine has published simple inverter with just few ICs and Mosfets.
Of course there are some commercially available inverter cards (Digital Inverter)
with PICs costing no more than Rs.500/- with Quasi sinewave output and frills
of DSP. These are good for PCs and lighting but give lots of problem with fans & motors. They also give regulation of better than 1% in inverter mode and +/-10% in mains mode.
psdayama

[barkerben]

Yep - our circuit may not have been all that good after all, but it was good fun to make! We were building from scratch as much as possible - winding our own transformers, etc. There were a few of us doing it at once. One group had a novel way of stopping their mosfets from frying - a constant stream of freeze spray! Not exactly very practical, but certainly impressive :-)

One group tried a resonant inverter, but got bogged down with the problem of sensing the load parameters to match the resonance...

[barkerben]

Oh yes, that was it... I remember now.

We had 24v in, chopped using a full bridge to 20Khz AC, fed into a transformer, then rectified to high voltage DC using a diode ring. The ide of high frewuency was to reduce transofrmer size and losses. The high voltage DC was then chopped usign a second H bridge to a quasi sine output.

The trigger signals for both bridges were generated by the PIC. We wanted to replace the quasi sine bridge trigge with full sine, but never got around to it :-(

[robinjacob]

Hi Sougata,
Have you finally designed the sine wave inverter? I am really interested to see the design. If you can please send me a schematic.

Thanks and Regards
Robin Jacob.

[psdayama]

Hello!
just scroll down and U will find the schematic in jpg format.
I don't know if Saugata will give the code.
Some part he has already explained.

[sougata]

Hi there,

I did finish the project and managed low harmonic content and descent crest factor but need to improve on the distortion issues on mixed inductive loads.Please note that it is a commercial project and I just cannot share it on this forum. However I would certainly like to answer specific queries.

Off the track I would like to express my gratitude to PSDayama whome I met personally on my trip for the Microchip Master's Conference. A warm welcome and great hospitality moved me. I thank this forum too.

Regards

Sougata

[psdayama]

Hi Everybody,
I met this nice chap SAUGATA thru this forum and very happy to
interact on subject which Im trying to learn from scratch.Of course
I am little old (>55years) but one is student all his life!
I want to thank the forum for getting to know many young people
and their expertise and exploits ;-)
Lets hope everybody gets on ahead with the subject matter.
Regards,
psdayama

[psdayama]

Following link gives description various design slides available:
http://ece-www.colorado.edu/~pwrelec.../slidedir.html
Check them for transformer & Inductor.
psdayama

[robinjacob]

Hi,
Atleast somebody give me a schematic of the inverter with uC. I would like to know about the snubber circuit and the ouput filter circuit. Could somebody help me out.

[mincing]

Hi I browsed through the forum.
Which JPG were you talking about!

Hello!
just scroll down and U will find the schematic in jpg format.
I don't know if Saugata will give the code.
Some part he has already explained.

[sougata]

Hi Mincing,

I would like to know which Avago(Agillent ?? ) drivers you are using and which MOSFETs. What is the intended configuration and if it is being directly connected to load or by a transformer.

Please give the required spec of your design in details.

[mincing]

i am using ACNW3130.seems to be of right choise.Welcome any comments.

I am using a full bridge configuration.with isolation transformer at the out put.Bridge would feed transformer.