I agree, "Optimistic" being the key word!
Got to say with the level of skill and creative electronic engineering people posses these days, I thought someone would have tackled this now and come up with a cheap and cheerful solution.
You are definitely right in what you say. Making power with these things is a cakewalk. Controlling it is a very different matter.
I found using the solar inverter had severe limitations as well. The inverter kept looking for the sweet spot and varying the load.
An imag is really only good for about half the motors rating which was not what I have seen written and threw me off for a while wondering why I couldn't get a lot more efficiency. I came to the 50% Conclusion about the same time I read something new on the concept which said the same thing.
Trouble was I was using an inverter that had about 50% of the load capability and my motor and therefore was trying to run it at the top end of its output. Once you get there, the load on the driving motor seems to go exponential.
I was trying to drive a 5HP motor with a 12 HP diesel engine and had the diesel smoking it was working so hard just to try and make 3Kw the inverter was trying to pull. When running lights etc at 1800W, the engine was barely turning over and I have used a grunty 3 HP diesel to make the same power with no trouble. The 2 KW Solar Inverter I had just flat out didn't seem compatible with the power supply and would kick out almost as quick as it put load on the IMAG.
I was pretty hopeful of this setup. Bought some 3 phase rectifiers to make the setup easier than using individual single phase units ( I also bought a heap of) and thought I could get it to load constantly but couldn't manage that. The inverters have far greater tolerance in input than the IMAG has for load.
It seems to me that the best and most practical application for the IMAGS is to back feed the mains supply to spin your meter backwards or run lights or a heating element. This works really well either by Direct connection, 2 Legs connected for single phase or 1 leg and neutral, a C2C setup to use all 3 legs and bring them back to single phase or all 3 legs for 3 phase.
I found that unlike what everyone says, Running the load imbalanced seemed to not make a bit of difference to the motor. I tested the thing well loaded up on both 2 legs and a single leg and Neutral and saw no frequency issues and certainly no overheating as I have read much about. I figure that is really illogical anyway. The motor I have has a LOT of thermal heat sinking capacity and a very strong fan. By only using 2 legs you are under running the thing and leaving a lot of provision for heatsinking the load that the motor is carrying which in this case would be a lot less than the thing as designed for in normal full load operation.
Pulling all the power I could get off 2 legs barely made the motor warm although it was easy to tell where the 2 winding's were that were supplying the power.
The other thing I have done with these motors is run them off single phase and use the 3rd leg to supply power to a 3 phase load also running off a single phase output. All you need to do to run a 3 phase motor ( at reduced output) is spin the thing to start it ( or use caps to phase shift).
I wrapped a rope around the pulley of the motor and spun it up lawnmower or outboard style then hit the switch connecting it to the single phase output.
They run perfectly. The 3rd free leg is connected to the 3phase load / motor that is also wired to the single phase load and it can be switched on as normal. Fun to play with and very simple.
Rotary converters are a bit wasteful I think for practical use. All you need to do to run a 3 phase motor off single phase is wire in come caps and they will work perfectly well. Setting up a rotary is fun to impress friends and the electrically curious though.
So much you can do with these Cheap and plentiful motors but it seems setting them up as a stand alone generator is rather a challenge!