250 watt grid tie inverter build - Page 5 - Electronic Circuits Projects Diagrams Free

tcmtech · 6th April 2009, 03:16 AM

This GTI build up Thread is intended for residants of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considerd a pirate Grid tie operation, which is considered illegal in many countries!

CONTROL CIRCIUT FUNCTIONS.

Here are the primary control functions you should be using in your GTI.

OUTPUT MONITORING.

The AC side MUST have a minimum of at least the peak line voltage high-low monitoring circuit with the time delay. This tells the GTI if it’s safe to actually connect to the AC line or not. It must override all DC side control functions!
The AC side MUST also have line frequency monitoring and it is set up like the AC side peak line voltage monitoring function as well. It watches the line frequency and will not let the GTI actually connect if the line frequency is too high or to low. It too must override all DC side control functions!

INPUT STAGING

This is still recommended but however it is optional depending upon the GTI design setup you have chosen. The control transformers can be turned on and off using a window comparator circuit with a delay timer in order to make the system more efficient. This optional control circuit will turn on the control transformers a few volts below when the GTI actually connects to the line. This will allow the power transformer and power circuits to be already running and will make the connection to the AC line nearly seamless. With the time delay the GTI can disconnect when the input power is too low for powere feedback but not actually shut down until the time delay has been run. This allows the GTI to idle during short dips in the input power without actually turning off every time.
Again this greatly smoothes out the connecting and disconnecting with the AC lines and saves on standby power, but is purely optional.

MULTI LEVEL SWITCHING.

This is also an optional control function. This will make it possible for the GTI to run two or more voltage input stages. This allows the power transformer to switch between high and low input voltage ranges automatically if it has the extra taps on the primary and or secondary windings.
This control circuit is the same as the window comparator circuits used by both of the other DC control sections. It will allow the power transformer to run on the low voltage input up to the amp limit of the transformers windings and then switch to the high voltage input. This makes a very good power scavenger function as it allows the GTI to pick up the lowest possible input power it can and still be able to feed it back into the AC lines.
The high range function allows the GTI to then use the more powerful and more efficient input power available without needing to run at low volts and high amps.
It your power transformer has a tap on the line side of it another control circuit can also be added to give it one more range also. This would give it a 3 stage capability!
Just make sure that when switching taps from one to the other that one tap is turned of before the other is connected!

tcmtech · 7th April 2009, 04:28 AM

This GTI build up Thread is intended for residants of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considerd a pirate Grid tie operation, which is considered illegal in many countries!

This is the actual circuit layout for the power and control transformers.

The control transformer is shown as a single unit with 4 isolated secondary taps. However 2 transformers with dual isolated secondaries or 4 single transformers will work too. The control transformer assembly is a voltage source only circuit so very small transformers can be used.

The small round dots on the power and control transformers designate the phase relationship between each winding.

TR1 and TR2 control the actual transformer connection with the AC line.
TR3 and TR4 are optional for a single line source system. They are only needed for a dual line American style 120/240 volt system.

TR1 -TR4 are actually solid state relays but can be mechanical relays instead if the drive signal from the control circuit is designed to work with them.

D1 -D8 are 15 volt 1w Zener diodes. These are to prevent the switching devices from getting too high of gate voltage. They should be mounted as close to the switching devices as possible!

Q1 - Q4 can be single high amp switching devices or several single units in parallel at each corner of the H-bridge circuit.
Q1 - Q4 can also be a pair of half bridge units as well.
The actual components and layout are up to the builder.

X1 and X2 are opto coupler driven SCR's but they too can be replaced with mechanical relays if the control circuit is designed to work with them.

See schematic attached below.

electronrancher · 9th April 2009, 07:42 AM

Hey all,

Just thought I'd pop in and say I'm still alive.

I just got my SSI-200W and tore it down without even powering it up. Some *VERY* clever stuff in there, but I have to say this:
It will never, ever, not in a million years, be OK'd for UL1741. The THD alone would take a big redesign to pass. I'll power it up tomorrow and try to take some scope shots of the AC current driven back into the grid, but it's got a cheap-'n-dirty self-biased H-bridge to do the polarity swap right at the grid interface. Effective, if you don't mind a 0.8ms dead time and a 30v step chopping off the zero-crosses of your sine wave. But alas, we US-ers are stuck with these pesky regulations that say a sine should be at least mostly a sine.

Other than that, it seems like a very capable device and the topology is freakin brilliant. The brains are an Atmega8 running at 16MHz. They must flash it after assembly because the full programming port is right there populated in the board. Haven't checked if code protect bits are set, but it would be total amatuer hour if they were not, so I'm not expecting to read out their ROM or anything.

tcmtech · 9th April 2009, 03:39 PM

Quote:

The brains are an Atmega8 running at 16MHz.

That sounds cool and all, But I can still kick its butt with all analog!

What frequency does analog run at? Oh wait thats right, I does not need one!

How about some pictures? I think we all would like to have a look!

Sceadwian · 9th April 2009, 04:16 PM

I doubt I could do much from the hex to ASM from the Mega8 if it doesn't have the lockbits set but I wouldn't mind a copy of the hex if you can dig it out, eeprom too.

You should be careful tcm you'd be surprised what you can do with a micro controller given solid power electronics and analog support. AVR makes some nice chips that have PLL's for their timers that allow 8bit PWM at 100+khz. Throw in a good fet and some filtering and you can have nearly a pure sinewave inverter. I'd be curious to see the scope view's of the inverter too.

tcmtech · 9th April 2009, 05:35 PM

I am just teasing him!

Quote:

you'd be surprised what you can do with a micro controller given solid power electronics and analog support.

Quote:

some filtering and you can have nearly a pure sinewave inverter

But still how much code and procesing does it take to make a sine wave that an LC tank can do naturaly?

And dont those filters at the end work like LC tanks to clean up that digital "nearly almost sort of looks like a signwave" wave form?

I do understand the versitility and adaptibility of digital control and I do use it more than I ever show here on this forum.
But I am just more of an analog man myself!

To me digital control seems to most often beused by theorists that are trying to make something act the way they think it shoud and not actualy letting it work the way is would natualy.

Digital is very fussy about working enviroment and conditions and is not forgiving to the unknown and odd variables that come with being in that enviroment or working conditions.

I am just an analog fan myself! I view things from a practicality aproch.
I dont see the point of overcomplicating things if its not nessisary.

Digital has its place and so does analog.

electronrancher · 9th April 2009, 06:51 PM

Well the digital/analog war seem to have already started. But I have to say, the verdict on the SSI-200 is.... Analog!

My guess is the micro is just to do the input/output shutoff requirements and the MPPT, the heart of the beast is an old unitrode UCC3806 push pull.

-First pic (overall_small.jpg) shows what is required to reverse engineer any device. One multimeter and said device, disassembled.

-Second pic (top_small.jpg) gives a better view of the top of the board. All your power components are here. DC input on the right, AC output on the left.
Starting from the right top, you can see the 4 mosfets (75v) that make up the push-pull and the big yellow push pull transformer.
Next in the signal path is at the bottom, two big toroid inductors and two diode bridges (the 8 devices at the bottom edge). Here your push pull output is rectified to HV DC (kinda).
Last in the signal path is the top left, the 4 mosfets (800v) that make up the H-bridge. They output to another smaller toroid inductor which then pipes into the smaller common mode transformer who connects to the line.

-Third pic (bottom_small.jpg) shows the belly of the beast. Atmega8 up in the upper right hand corner, and UCC3806 in the middle right. They tried to grind off the part numbers, but did a half-ass job. The only one they actually ground off successfully was the little SO8 next to the UCC3806. But alas, that IC has a bevelled edge which only comes from one manufacturer - duh! Trace power and ground, and discover that it can only be an op-amp. It's used to buffer the sine wave sensed off the grid and send it back to the control circuitry.

Good things: Push-pull is very clever and CHEAP. Output H-bridge is truly brilliant, first I've seen of it's kind. And overall topology is simple yet effective - the mark of a durable, reliable device.

Bad things - grid is not really isolated from the input (fatal flaw) because the sine wave feedback runs right into the op-amp and back to the low voltage side. One lightning strike to your power pole and your inverter, panel, charge controller, and maybe yourself, are fried. Also, H-bridge is sloppily implemented and does not give clean switching so THD is well outside the spec.

Next victim: the SWEA, if it ever comes. Beware the lowest-cost ebay seller, he does not seem to have the devices he's selling and is not at all straightforward in his communication about it. Excuses and lies, mostly.

tcmtech · 9th April 2009, 10:06 PM

Can't call it a war if there is no other side to challenge!

From what I've been experimenting with over the years I can't honestly say that anything but good old analog and a big heavy iron core transformer can be beat for rubustness, reliability, cost, and just all around simplicity! They can take a vicious electrical beating and still keep on going. Plus just by design it can give a good sinewave output even with less than ideally matched parts!

However for the control and monitoring end I do like digital control! I do actualy use a PLR system on my bigger designs.
All its doing is monitoring the system and doesn't actualy have any control over the wave forms. Its just a good babysitter and lets the analog do what its does best. The only time it actualy interacts with the analog side of the system is during a stage change or an out of range shutdown.
Even then all it gets to do is on/off control over the input connection, output connection or voltage range changing devices.

In my opinion they both work best when used together. Let the analog do the power handling grunt work, its what it does best! Then deligate the logic of what to watch and what to do about it to the digital.

Digital has got the brains but lacks the natural muscle and robustness that analog packs when it comes to doing the power work.

tcmtech · 26th April 2009, 09:41 PM

This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries!

Thanks for sitting through a long delay in my getting more schematics done. The weather warmed up and the snow melted so I have been spending most of my time working outside again.

I hope you have been able to get the power handling circuit built and somewhat tuned up and tested to some degree by now.

Here is the schematic for the actual frequency monitoring circuit. This is based on an actual working unit, However I did leave several component values blank due to the large differences in voltage, frequency and possible component substitutes that may be encountered with this build.

I did give you a basic reference legend that will give you the reasons why for each component.

So. Sorry, but this circuit does require you to do some math and a little component matching of your own!

And dont overlook that this is a line powered circuit, So use extra caution while testing and tweaking.

If you need a clearer understanding of how this circuit works I have references to its functions in earlier posts.

tcmtech · 26th April 2009, 11:26 PM

This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries!

Here is the schematic for the actual peak line voltage monitoring circuit. This is based on an actual working unit too, However I did again leave several component values blank due to the large differences in voltage, frequency and possible component substitutes that may be encountered with this build. Blah, blah, blah.

I did give you a basic reference legend again that will give you the reasons why for each component.

So. Sorry again, but this circuit does require you to do some math too and a little component matching of your own!

(yea I cut and pasted to save some time)

This is nearly the same circuit as the frequency monitoring circuit so if your using a four comparator IC you can easily just add this to the circuit and not need to build two separate monitoring systems.
The original ones I built were independent of each other. (different design and development times)
However there is no reason that these two could not be combined onto one IC and one power source.

I could have morphed these together onto one schematic too, but this way makes it easier to read and follow.

And dont overlook that this is still a line powered circuit, So use extra caution while testing and tweaking.

If you need a clearer understanding of how this circuit works I have references to its functions in earlier posts.

tcmtech · 27th April 2009, 04:08 AM

This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries!

Well this is what a complete GTI schematic looks like! Well sort of.
I condensed the control circuits down as simple function blocks to show how they are connected in the actual GTI design.

But this should give you an actual conceptual look at how they interact with the system and with each other.

I provided basic block reference numbers so you could have some idea of what each block represents in the actual circuit. And the notes are for reference to misc other things as well.

The DC side control circuits can be powered off of the actual DC source if its minimum low range voltage is high enough.
This wont work for systems that have less than a 12 volt low range.
So for the lower voltage higher current designs a standard step down transformer and power supply will be needed in order to drive it from the line side power. Being a low powered circuit, the transformer can be very small.

The AC side control circuits must be electrically isolated from the control signal that they interrupt.
The actual AC control circuit design could be modified to run off a small transformer and be added to the DC control circuits if needed.

The whole point of the long write ups and circuit descriptions is to give you a basic understanding of what each component does. This will make changing the circuit to suit your own design or needs simpler and easier.
None of the actual component sizes or circuit layouts are set in stone.
As long as you keep the design parameters in mind there are countless ways of modifying and controlling this system!

If your good with Microcontrollers, toss the whole analog control system out and go all code! If you want greater efficiency with the switching circuits toss the control transformer and go with all Mosfet/IGBT driver IC's!
If you have actually built a full analog GTI and have it working and understand why it works, what ever you change or modify is entirely up to you!

Just remember the safety and control rules and stay within the laws and regulations of your area.

Here is the actual notes from the block diagram. The picture seems to wan to convert to a blurry image for some reason.

TR1 -TR4 are solid state relays.
Mechanical relays can also be used but control system circuits may need to be modified to work with them.
X1 -X2 are SCR opto coupler triggered.
Mechanical relays can also be used but control system circuits may need to be modified to work with them.
BLOCK UNIT DISCRIPTIONS.
1: system standby circuit.
Powers up the control transformer before connection to the lines.
Also serves as standby/off control for DC side of the system.
2: Stage one control.
Turns on X2, TR1 &TR3 for standby/run mode changes
3: Stage two control.
Turns on X1 for low high mode changes.
4: AC line side monitoring.
Overrides signal to TR2 & TR4 preventing control system activation if line conditions are wrong.
Also overrides signals to TR1 &TR3 preventing main power system activation if line conditions are wrong.
Can also overide X1 & X2 activation if needed.
* optional timer function blocks are not shown.
If needed timers can be built into the independent control circuits.

DC side control power.
This can be supplied from the systems DC input
power source if the minimum running point
input voltge is high enough.
Otherwise from an AC line side driven power source.
(isolated stepdown transformer)

Sceadwian · 27th April 2009, 05:52 AM

tcm I can't read a single line of text in that last image.

bbhs · 27th April 2009, 07:16 AM

Hi Sceadwian - if using IE then try the page zoom function the text can then be read.

Jules_Theone · 27th April 2009, 08:49 AM

I was experimenting with the grid tie inverter idea again at the weekend, and looking at your H-bridge / transformer setup. I don't understand why the centre-tap of the transformer is connected to +ve through X2. One of the transformers I have deosn't have a centre-tap and as far as I can see it's not required. Correct me if I'm wrong but as the centre in connected to +ve al the time, when Q1 or Q4 are on they will effectively short across the top winding of the transformer? I set my circuit up without the centre-tap but using the full H-bridge and it looked ok before i connected it to the grid...

jonasdz · 27th April 2009, 04:19 PM

How do you control the amount of current/power? It looks like your system can work for feeding energy to the grid but I don't understand how you can control it with this basic design. If you want to use it for solar panels, it is a "must" to have control.

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6th April 2009, 03:16 AM	#61
tcmtech	Control system Component Function Basics II. This GTI build up Thread is intended for residants of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considerd a pirate Grid tie operation, which is considered illegal in many countries! CONTROL CIRCIUT FUNCTIONS. Here are the primary control functions you should be using in your GTI. OUTPUT MONITORING. The AC side MUST have a minimum of at least the peak line voltage high-low monitoring circuit with the time delay. This tells the GTI if it’s safe to actually connect to the AC line or not. It must override all DC side control functions! The AC side MUST also have line frequency monitoring and it is set up like the AC side peak line voltage monitoring function as well. It watches the line frequency and will not let the GTI actually connect if the line frequency is too high or to low. It too must override all DC side control functions! INPUT STAGING This is still recommended but however it is optional depending upon the GTI design setup you have chosen. The control transformers can be turned on and off using a window comparator circuit with a delay timer in order to make the system more efficient. This optional control circuit will turn on the control transformers a few volts below when the GTI actually connects to the line. This will allow the power transformer and power circuits to be already running and will make the connection to the AC line nearly seamless. With the time delay the GTI can disconnect when the input power is too low for powere feedback but not actually shut down until the time delay has been run. This allows the GTI to idle during short dips in the input power without actually turning off every time. Again this greatly smoothes out the connecting and disconnecting with the AC lines and saves on standby power, but is purely optional. MULTI LEVEL SWITCHING. This is also an optional control function. This will make it possible for the GTI to run two or more voltage input stages. This allows the power transformer to switch between high and low input voltage ranges automatically if it has the extra taps on the primary and or secondary windings. This control circuit is the same as the window comparator circuits used by both of the other DC control sections. It will allow the power transformer to run on the low voltage input up to the amp limit of the transformers windings and then switch to the high voltage input. This makes a very good power scavenger function as it allows the GTI to pick up the lowest possible input power it can and still be able to feed it back into the AC lines. The high range function allows the GTI to then use the more powerful and more efficient input power available without needing to run at low volts and high amps. It your power transformer has a tap on the line side of it another control circuit can also be added to give it one more range also. This would give it a 3 stage capability! Just make sure that when switching taps from one to the other that one tap is turned of before the other is connected! __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech Last edited by tcmtech; 6th April 2009 at 05:06 AM.

7th April 2009, 04:28 AM	#62
tcmtech	Power & Control Transformer Circuit This GTI build up Thread is intended for residants of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considerd a pirate Grid tie operation, which is considered illegal in many countries! This is the actual circuit layout for the power and control transformers. The control transformer is shown as a single unit with 4 isolated secondary taps. However 2 transformers with dual isolated secondaries or 4 single transformers will work too. The control transformer assembly is a voltage source only circuit so very small transformers can be used. The small round dots on the power and control transformers designate the phase relationship between each winding. TR1 and TR2 control the actual transformer connection with the AC line. TR3 and TR4 are optional for a single line source system. They are only needed for a dual line American style 120/240 volt system. TR1 -TR4 are actually solid state relays but can be mechanical relays instead if the drive signal from the control circuit is designed to work with them. D1 -D8 are 15 volt 1w Zener diodes. These are to prevent the switching devices from getting too high of gate voltage. They should be mounted as close to the switching devices as possible! Q1 - Q4 can be single high amp switching devices or several single units in parallel at each corner of the H-bridge circuit. Q1 - Q4 can also be a pair of half bridge units as well. The actual components and layout are up to the builder. X1 and X2 are opto coupler driven SCR's but they too can be replaced with mechanical relays if the control circuit is designed to work with them. See schematic attached below. Attached Thumbnails __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech

9th April 2009, 07:42 AM	#63
electronrancher	Hey all, Just thought I'd pop in and say I'm still alive. I just got my SSI-200W and tore it down without even powering it up. Some VERY clever stuff in there, but I have to say this: It will never, ever, not in a million years, be OK'd for UL1741. The THD alone would take a big redesign to pass. I'll power it up tomorrow and try to take some scope shots of the AC current driven back into the grid, but it's got a cheap-'n-dirty self-biased H-bridge to do the polarity swap right at the grid interface. Effective, if you don't mind a 0.8ms dead time and a 30v step chopping off the zero-crosses of your sine wave. But alas, we US-ers are stuck with these pesky regulations that say a sine should be at least mostly a sine. Other than that, it seems like a very capable device and the topology is freakin brilliant. The brains are an Atmega8 running at 16MHz. They must flash it after assembly because the full programming port is right there populated in the board. Haven't checked if code protect bits are set, but it would be total amatuer hour if they were not, so I'm not expecting to read out their ROM or anything.

9th April 2009, 04:16 PM	#65
Sceadwian	I doubt I could do much from the hex to ASM from the Mega8 if it doesn't have the lockbits set but I wouldn't mind a copy of the hex if you can dig it out, eeprom too. You should be careful tcm you'd be surprised what you can do with a micro controller given solid power electronics and analog support. AVR makes some nice chips that have PLL's for their timers that allow 8bit PWM at 100+khz. Throw in a good fet and some filtering and you can have nearly a pure sinewave inverter. I'd be curious to see the scope view's of the inverter too. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

9th April 2009, 06:51 PM	#67
electronrancher	Well the digital/analog war seem to have already started. But I have to say, the verdict on the SSI-200 is.... Analog! My guess is the micro is just to do the input/output shutoff requirements and the MPPT, the heart of the beast is an old unitrode UCC3806 push pull. -First pic (overall_small.jpg) shows what is required to reverse engineer any device. One multimeter and said device, disassembled. -Second pic (top_small.jpg) gives a better view of the top of the board. All your power components are here. DC input on the right, AC output on the left. Starting from the right top, you can see the 4 mosfets (75v) that make up the push-pull and the big yellow push pull transformer. Next in the signal path is at the bottom, two big toroid inductors and two diode bridges (the 8 devices at the bottom edge). Here your push pull output is rectified to HV DC (kinda). Last in the signal path is the top left, the 4 mosfets (800v) that make up the H-bridge. They output to another smaller toroid inductor which then pipes into the smaller common mode transformer who connects to the line. -Third pic (bottom_small.jpg) shows the belly of the beast. Atmega8 up in the upper right hand corner, and UCC3806 in the middle right. They tried to grind off the part numbers, but did a half-ass job. The only one they actually ground off successfully was the little SO8 next to the UCC3806. But alas, that IC has a bevelled edge which only comes from one manufacturer - duh! Trace power and ground, and discover that it can only be an op-amp. It's used to buffer the sine wave sensed off the grid and send it back to the control circuitry. Good things: Push-pull is very clever and CHEAP. Output H-bridge is truly brilliant, first I've seen of it's kind. And overall topology is simple yet effective - the mark of a durable, reliable device. Bad things - grid is not really isolated from the input (fatal flaw) because the sine wave feedback runs right into the op-amp and back to the low voltage side. One lightning strike to your power pole and your inverter, panel, charge controller, and maybe yourself, are fried. Also, H-bridge is sloppily implemented and does not give clean switching so THD is well outside the spec. Next victim: the SWEA, if it ever comes. Beware the lowest-cost ebay seller, he does not seem to have the devices he's selling and is not at all straightforward in his communication about it. Excuses and lies, mostly. Attached Thumbnails

9th April 2009, 10:06 PM	#68
tcmtech	Can't call it a war if there is no other side to challenge! From what I've been experimenting with over the years I can't honestly say that anything but good old analog and a big heavy iron core transformer can be beat for rubustness, reliability, cost, and just all around simplicity! They can take a vicious electrical beating and still keep on going. Plus just by design it can give a good sinewave output even with less than ideally matched parts! However for the control and monitoring end I do like digital control! I do actualy use a PLR system on my bigger designs. All its doing is monitoring the system and doesn't actualy have any control over the wave forms. Its just a good babysitter and lets the analog do what its does best. The only time it actualy interacts with the analog side of the system is during a stage change or an out of range shutdown. Even then all it gets to do is on/off control over the input connection, output connection or voltage range changing devices. In my opinion they both work best when used together. Let the analog do the power handling grunt work, its what it does best! Then deligate the logic of what to watch and what to do about it to the digital. Digital has got the brains but lacks the natural muscle and robustness that analog packs when it comes to doing the power work. __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech

26th April 2009, 09:41 PM	#69
tcmtech	Line Frequency Monitor Circuit. This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries! Thanks for sitting through a long delay in my getting more schematics done. The weather warmed up and the snow melted so I have been spending most of my time working outside again. I hope you have been able to get the power handling circuit built and somewhat tuned up and tested to some degree by now. Here is the schematic for the actual frequency monitoring circuit. This is based on an actual working unit, However I did leave several component values blank due to the large differences in voltage, frequency and possible component substitutes that may be encountered with this build. I did give you a basic reference legend that will give you the reasons why for each component. So. Sorry, but this circuit does require you to do some math and a little component matching of your own! And dont overlook that this is a line powered circuit, So use extra caution while testing and tweaking. If you need a clearer understanding of how this circuit works I have references to its functions in earlier posts. Attached Thumbnails __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech Last edited by tcmtech; 26th April 2009 at 11:28 PM.

26th April 2009, 11:26 PM	#70
tcmtech	Peak Line Voltage Monitor Circuit. This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries! Here is the schematic for the actual peak line voltage monitoring circuit. This is based on an actual working unit too, However I did again leave several component values blank due to the large differences in voltage, frequency and possible component substitutes that may be encountered with this build. Blah, blah, blah. I did give you a basic reference legend again that will give you the reasons why for each component. So. Sorry again, but this circuit does require you to do some math too and a little component matching of your own! (yea I cut and pasted to save some time) This is nearly the same circuit as the frequency monitoring circuit so if your using a four comparator IC you can easily just add this to the circuit and not need to build two separate monitoring systems. The original ones I built were independent of each other. (different design and development times) However there is no reason that these two could not be combined onto one IC and one power source. I could have morphed these together onto one schematic too, but this way makes it easier to read and follow. And dont overlook that this is still a line powered circuit, So use extra caution while testing and tweaking. If you need a clearer understanding of how this circuit works I have references to its functions in earlier posts. Attached Thumbnails __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech Last edited by tcmtech; 26th April 2009 at 11:28 PM.

27th April 2009, 04:08 AM	#71
tcmtech	GTI Function Block Schematic This GTI build up Thread is intended for residents of the united states only! Should you decide to build and use such a device as this you may be breaking laws and can face possible fines, and or jail and prison time for it. Should you chose to build such a device as this and intend to use it for saving energy in your home or dwelling you are still breaking the law. Beware you are considered a pirate Grid tie operation, which is considered illegal in many countries! Well this is what a complete GTI schematic looks like! Well sort of. I condensed the control circuits down as simple function blocks to show how they are connected in the actual GTI design. But this should give you an actual conceptual look at how they interact with the system and with each other. I provided basic block reference numbers so you could have some idea of what each block represents in the actual circuit. And the notes are for reference to misc other things as well. The DC side control circuits can be powered off of the actual DC source if its minimum low range voltage is high enough. This wont work for systems that have less than a 12 volt low range. So for the lower voltage higher current designs a standard step down transformer and power supply will be needed in order to drive it from the line side power. Being a low powered circuit, the transformer can be very small. The AC side control circuits must be electrically isolated from the control signal that they interrupt. The actual AC control circuit design could be modified to run off a small transformer and be added to the DC control circuits if needed. The whole point of the long write ups and circuit descriptions is to give you a basic understanding of what each component does. This will make changing the circuit to suit your own design or needs simpler and easier. None of the actual component sizes or circuit layouts are set in stone. As long as you keep the design parameters in mind there are countless ways of modifying and controlling this system! If your good with Microcontrollers, toss the whole analog control system out and go all code! If you want greater efficiency with the switching circuits toss the control transformer and go with all Mosfet/IGBT driver IC's! If you have actually built a full analog GTI and have it working and understand why it works, what ever you change or modify is entirely up to you! Just remember the safety and control rules and stay within the laws and regulations of your area. Here is the actual notes from the block diagram. The picture seems to wan to convert to a blurry image for some reason. TR1 -TR4 are solid state relays. Mechanical relays can also be used but control system circuits may need to be modified to work with them. X1 -X2 are SCR opto coupler triggered. Mechanical relays can also be used but control system circuits may need to be modified to work with them. BLOCK UNIT DISCRIPTIONS. 1: system standby circuit. Powers up the control transformer before connection to the lines. Also serves as standby/off control for DC side of the system. 2: Stage one control. Turns on X2, TR1 &TR3 for standby/run mode changes 3: Stage two control. Turns on X1 for low high mode changes. 4: AC line side monitoring. Overrides signal to TR2 & TR4 preventing control system activation if line conditions are wrong. Also overrides signals to TR1 &TR3 preventing main power system activation if line conditions are wrong. Can also overide X1 & X2 activation if needed. * optional timer function blocks are not shown. If needed timers can be built into the independent control circuits. DC side control power. This can be supplied from the systems DC input power source if the minimum running point input voltge is high enough. Otherwise from an AC line side driven power source. (isolated stepdown transformer) Attached Thumbnails __________________ "Issue a general safety warning. Then look the other way and allow stupidity the chance to eliminate itself." -- tcmtech "Those who can, Will. Those who can't, will achieve positions of power over those who can and then promptly stop them." -- tcmtech "Your impossibility may just be my day to day routine." -- tcmtech Last edited by tcmtech; 28th April 2009 at 03:24 PM.

27th April 2009, 05:52 AM	#72
Sceadwian	tcm I can't read a single line of text in that last image. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

27th April 2009, 07:16 AM	#73
bbhs	Hi Sceadwian - if using IE then try the page zoom function the text can then be read.

27th April 2009, 08:49 AM	#74
Jules_Theone	I was experimenting with the grid tie inverter idea again at the weekend, and looking at your H-bridge / transformer setup. I don't understand why the centre-tap of the transformer is connected to +ve through X2. One of the transformers I have deosn't have a centre-tap and as far as I can see it's not required. Correct me if I'm wrong but as the centre in connected to +ve al the time, when Q1 or Q4 are on they will effectively short across the top winding of the transformer? I set my circuit up without the centre-tap but using the full H-bridge and it looked ok before i connected it to the grid... Attached Thumbnails Last edited by Jules_Theone; 27th April 2009 at 08:54 AM.

27th April 2009, 04:19 PM	#75
jonasdz	power control How do you control the amount of current/power? It looks like your system can work for feeding energy to the grid but I don't understand how you can control it with this basic design. If you want to use it for solar panels, it is a "must" to have control.