LAUGH OUT LOUD! and reLOL!
Of course I do not know anything and this since almost 30 years specializes in engine controls.
What solution you propose to our friend instead of insulting me hastily.
Blackberry
You can use a three-phase AC variable control directly on your gene. and use your engine without any problem but as I mentioned you will have no performance in uphill and acceleration.
This control converts the AC to DC internally and reproduces an AC waved frequency to speed up your motor, the voltage can be controlled as well as the frequency.
Your generator is usually DC and converted into three AC phases and can normally compensate with regulators overload that will be minimal for a short time.
On the link you give the guy is a little complicated life because it uses AC and a charger that we see very well in the trunk that charges or helps the batteries and uses a DC controller and a DC motor has brush very good bill that is used on the forklift, good the price of all this can convince you to drop, besides the consumption does not count the electricity to charge the batteries which in itself should still to be added for a real reading of consumption.