Re:Glowing mercury thyratrons: inside a 1940s Teletype switc...
by sephamorr on Tuesday September 11, 2018 @02:05PM
(#17961959)
What you've built here is a rudimentary boost converter, using the motor inductance as your inductor, and your battery as your output capacitance.
The next step up here is to build a controllable device that can implement maximum power point tracking; a buck-boost power topology might be what you're looking for here.
Note that MPPT on a wind turbine is more difficult than, say solar, because the rotor speed is another state variable to consider. A naive/greedy algorithm might apply maximum torque to the rotor to extract maximum power for a moment, but this strategy will try to stall the rotor. As power is torque * angular velocity, both terms require consideration.
But a windmill is mostly coils and magnets and when you short it it actually will charge the battery, briefly robbing the blades of some momentum. So, if you periodically short the coils using a bunch of powerfets and an oscillator you can charge a windmill in low wind conditions that would otherwise do nothing.
So far so good. Built it, tested it, worked like a charm. And then one day I decided to temporarily decouple the windmill from the switchboard, but I had forgotten about that little booster. FOOM, instant fire on the booster board after I pulled the switch. The FET circuitry and the oscillator had happily continued to work on the power provided by the windmill, and had allowed the end stage of the circuit to reach a very large multiple of the voltage that it normally dealt with because the battery kept the voltage pegged to a maximum of about 48V!
Needless to say that led to a somewhat more robust V2...