i need urgent help designing an inverter using the parts i have

[alec_t]

Looks like the module on the right is driven at the base 50/60Hz, whereas the one on the left is PWM'ed at umpteen kHz to give a sinusoidal average amplitude.

 

[spec]

https://www.industrial-electronics.com/images/elec-pwr_7-15a.jpg
i just saw this and wondered, why are they driving the second module a separate waveform instead of the spwm lines crossed over from the first module. am i being more stupid than usual, or is it for gate drive efficiency?

That schematic is correct. For one half cycle of the output waveform it is much better to just switch one IGFET on and pulse width modulate the other to obtain a half sine function.

In that diagram it would be better to switch Q1 and Q3 and pulse width modulate Q4 and Q2.

spec

 

[spec]

Hy edddyyyy,

I have read all the posts both here and on AAC a number of times- Hell, you have been given the run around and I can't see why

Can I ask a few fundamental questions, just for information- nothing more:

(1) What are the details of the pump motor: voltage (110V, 240V), current (run and start), frequency (50 or 60Hz).
(2) Are both input terminals of the pump motor fully isolated or is one connected to the case. If the later applies it will be necessary to use an isolating transformer unless you can tolerate having the solar panel jumping up and down at mains voltage.
(3) You imply that you cannot buy components from distributors, but what components do you have apart from the IGBTs and drivers: resistors, capacitors, transistors, etc. If not, can you salvage components from other equipment.
(4) Do you have sufficient tools and skills for the mechanical construction of an inverter
(5) Do you have sufficient electrical tools and skills to wire an inverter and test it: soldering iron, solder, small pliers, wire cutters, multimeter.

spec

 

[tcmtech]

I find much of the run around to be rather self-inflicted due insufficient information other than he has a mix and match of cheap and overrated/overworked devices and what comes off as rather poor choices in the overall approach to the realistic problems at hand.

This is supposedly a near do or die situation yet it's been dragging on for weeks now plus several realistic and fairly easy to implement solutions to the pump driving situation have been given yet none have been shown any real interest.

Also things like his sine wave inverter burnt out and we have yet to get a single comment on what brand and model it was and what actually burned up, or how the overall system is designed other than it has no battery bank which is an absolute must for highly fluctuating loads like overloaded induction motors cycling on and of at random, in the unit which to me if I had a working inverter that burned out that would be my #1 priority to determine what burned up and why and if possible repair and reconfigure the unit to work better.

My guess is simple overheating and long term overloading was the basis of the problem which if so is not that difficult problem to fix.
That and he has the system running directly off the solar panels with no battery stabilization (says so over his AAC thread) to keep the DC side supply voltages stable during fluctuations in the solar panels output and the pumps start-run cycles as they overheat and shut down then reset which to me strongly suggests the inverters were being regularly subjected to wide ranges of input voltage dips and spikes when the pump motors would cyle on and off which is a pretty effective way to kill their switching devices.

Lastly, he says he is running his 500 watt rated pumps at ~800 plus watt loads until they overheat and shut themselves off which to me say that they are likely either units designed for deeper well higher lift applications than they are being used in and likely need some basic flow restriction to reduce their flow rates and related power draw down into their designed working range or they are designed for much shallower wells and are running near their maximum head pressure limits.

My take on this whole fiasco is that most of the major problems like the inverter burn down and the pump overloading could have been avoided had a pair of 12-volt 50+ Ah deep cycle batteries been in place on the 24 VDC supply and a simple valve to restrict the pumps flow rates down to where they are not running in an overloaded high flow low back presure or high back pressure low flow state been used which could have been easily figured out had the inverters manual and the pumps specs sheets been read and taken into account at the initial setup of the system.

That's my thoughts on this.

 

[spec]

I find much of the run around to be rather self-inflicted due insufficient information other than he has a mix and match of cheap and overrated/overworked devices and what comes off as rather poor choices in the overall approach to the realistic problems at hand.

This is supposedly a near do or die situation yet it's been dragging on for weeks now plus several realistic and fairly easy to implement solutions to the pump driving situation have been given yet none have been shown any real interest.

Also things like his sine wave inverter burnt out and we have yet to get a single comment on what brand and model it was and what actually burned up, or how the overall system is designed other than it has no battery bank which is an absolute must for highly fluctuating loads like overloaded induction motors cycling on and of at random, in the unit which to me if I had a working inverter that burned out that would be my #1 priority to determine what burned up and why and if possible repair and reconfigure the unit to work better.

My guess is simple overheating and long term overloading was the basis of the problem which if so is not that difficult problem to fix.
That and he has the system running directly off the solar panels with no battery stabilization (says so over his AAC thread) to keep the DC side supply voltages stable during fluctuations in the solar panels output and the pumps start-run cycles as they overheat and shut down then reset which to me strongly suggests the inverters were being regularly subjected to wide ranges of input voltage dips and spikes when the pump motors would cyle on and off which is a pretty effective way to kill their switching devices.

Lastly, he says he is running his 500 watt rated pumps at ~800 plus watt loads until they overheat and shut themselves off which to me say that they are likely units designed for deeper well higher lift applications than they are being used in and likely need some basic flow restriction to reduce their flow rates and related power draw down into their designed working range.
My take on this whole fiasco is that most of the major problems like the inverter burn down and the pump overloading could have been avoided had a pair of 12-volt 50+ Ah deep cycle batteries been in place on the 24 VDC supply and a simple valve to restrict the pumps flow rates down to where they are not running in an overloaded high flow state been used which could have been easily figured out had the inverters manual and the pumps specs sheets been read and taken into account at the initial setup of the system.

That's my thoughts on this.

Hy TCM,

I agree that you have provided technical advice and in general you are one of the top contributors on ETO, especially because of your obvious experience. It is the other stuff, from other parties too that is gratuitous on this particular thread. My feeling is that if an OP is not doing what you want or being annoying just walk away- I do it all the time even though it is frustrating, especially when you have put a lot of time and effort into the thread.

spec

 

[tcmtech]

The OP can do what eve he wants but when asking for engineering advice on how to do something with as little effort and resources as possible as quickly as possible without giving a full picture of what he has to work with and how it's set up and then taking weeks to convey any info makes no sense to me.

What I have figured out so far is that,

1. He has two 500 watt rated submersible pumps that require 230 VAC power.

2. His present power supply is based on 24-volt solar panels (~600 watts) and a solar charge/power controller going directly to the power inverters that run the pumps without any batteries between the solar power controller and the inverters to act as a power stabilization/buffering stage. ( I have strong suspicions is why the inverter burned up.)

3. The pumps he has are severely overloaded suggesting that they are either pumping way too much water without sufficient back pressure or they are pumping against way too much backpressure and are at near deadhead conditions and pumping too little water at too much head pressure for their design.

4. Figures the equipment is at fault and not the mix and match design that is missing key components and properly matched working capacities has little to do with it.

5. Capitalism is bad and spending money and planning to get the most out of your investment is a common capitalistic theme/strategy so............ Avoid both with maximum prejudice?

6. Pokes the bear yet doesn't like the bites he gets in return.

 

[spec]

The OP can do what eve he wants but when asking for engineering advice on how to do something with as little effort and resources as possible as quickly as possible without giving a full picture of what he has to work with and how it's set up and then taking weeks to convey any info makes no sense to me.

What I have figured out so far is that,

1. He has two 500 watt rated submersible pumps that require 230 VAC power.

2. His present power supply is based on 24-volt solar panels (~600 watts) and a solar charge/power controller going directly to the power inverters that run the pumps without any batteries between the solar power controller and the inverters to act as a power stabilization/buffering stage. ( I have strong suspicions is why the inverter burned up.)

3. The pumps he has are severely overloaded suggesting that they are either pumping way too much water without sufficient back pressure or they are pumping against way too much backpressure and are at near deadhead conditions and pumping too little water at too much head pressure for their design.

4. Figures the equipment is at fault and not the mix and match design that is missing key components and properly matched working capacities has little to do with it.

That may be the case, but don't forget that many people asking for help on ETO may not have the logical approach that you have.

But one thing that does seems odd to me is that the OP has constantly said that buying parts and equipment are not an option, but yet he has been told to do just that over and over.

The least we should do is to try to answer his questions and attempt to design an inverter giving the best performance possible, using the parts that he has, as he has requested.

The OP has a couple of decent twin IGBT modules which will make a suitable bridge. He also has five gate drivers, four of which will match the IGBTs, so at least the essentials are there. But, if both terminals of the motors are not isolated, that will necessitate an output transformer which will complicate the issue and the gate drivers are not the easiest to use because of the supply lines they require.

5. Capitalism is bad and spending money and planning to get the most out of your investment is a common capitalistic theme/strategy so............ Avoid both with maximum prejudice?

6. Pokes the bear yet doesn't like the bites he gets in return.

The OP did not start this tack as far as I can tell- it was a reaction to an assault on his lifestyle/circumstances from this end.

spec

 

[tcmtech]

Assuming it's a standard deep well pump then the wiring will be isolated from the case so I see no issues there.

If things can't be done logically and by the basic standards set forth by the experts who work with such systems and process they shouldn't be done at all. Especially so if there is a very limited budget and resources to work with.

Ignorance and unfamiliarity are understandable and easily forgiven. Driving full force forward with no clue and no real concerns to bothered with learning about what it is you actually want to accomplish and no practical knowledge of how the things you wish to use actually work and why when you have very limited resources isn't so forgivable in my views.

Wanting to live off the land while using modern technology is admirable. I'm all for it (been doing a bit of it myself for years) but doing so with no real plan other than to accumulate a large amount of odds and ends and then try to put them together with no clue as to how they work and why and what their limitation are for certain components that need to match is not something I care to work with.

If you have the time and resources to stumble along blindly without thinking and planning you have time and resources to stop and learn how what you want to accomplish needs to be done before doing it.

For me the big red flag was and is the trying to run inverters directly off of solar arrays while using nothing more than charge controllers to keep the DC voltages stable and no batteries in the system for a load that needs a stable fixed frequency and voltage while it has a highly variable current and power draw that at times can easily go well beyond the solar arrays working capacity.

 

[spec]

Some good points tcm

spec

 

[edddyyyy]

Op here. Have been away from the net weeding a mile of planted rows and making most use of the rain.
Tcmtech is getting distracted again, i did open a thred for him to add his comments about my choices.
The threads have been around a while because of other work and waiting for essential parts to arrive. Im still waiting for the isolated psu modules for the drivers.

I think theres also confusion about the system that blew.
The inverter had 200ah 24v bank.
The input caps blew off the pcb and a power resistor and the reg on the display board is toast.
I got together some cash and ordered the best inverter i could. Now waiting on a 5kw lf unit from power jack.
The old one was doppwer and is 2 stage. Mosfets look physically ok. Must be bad caps or how can two batteries soar to over 35v?
The genny is with my maister as i didnt have tools to disassamble further after its oil wee.
I expect the new inverter to fail but not as fast. Ideally i can build a better one before it happens. The old inverter may be fixable if i can leave out the display and if not then maybe i can salvage the parts to make a chopper to do 24v to 380 thus adding to the 380v solar. The burnt unit is better than some i seen. Has one big ferrite transformer instead of lots of little.
Pumps i know little of. 33litre a minute and im under head limit so why it drew 800 idkw. They both the same, never been ran together. One inch pipe with non returns that help out.

The old inverter was good for a few years on power tools and even ran a scope ok.
Yes it would be great to fix it.
I could add the 380v at the caps too. Help it out maybe with some extras as they are tight with pennys there.

 

[edddyyyy]

Ps 800w was reading on display, not dmm so maybe bs.