To efficiently use a wind
or hydro turbine there needs to be a controller to convert voltage. You cannot just run it to the battery
through diodes or something and expect good results.
voltage is relatively constant, but the turbine needs to run at a voltage related to the speed of the flow. So with twice the wind
, the voltage output doubles, and the current
is 4 times. The regulator
must convert this double voltage to 8 times the current
. If you force the turbine to run at the battery, the blades won't extract as much energy since they will be overloaded and you end up with less than 8 times the current.
If the generator
is connected directly to the battery, it will be efficient at only one specific speed. Otherwise it is like sailing with the sail too tight or too loose.
I have designed my mppt
controllers for solar
, a syncronous rectifier for wind/hydro (to avoid rectifier diode losses) and I'm working on a new mppt
for wind/hydro that can brake, buck and even boost the voltage to ensure the load (drag) on the turbine is optimal and I can easily charge both 12 and 48 v batteries
. The algorithm compared to wind is completely different as it deals with much larger input voltage (and therefore duty cycle) variations. Some wind turbines use wind speed/direction sensors, and some farms even network the data to anticipate gusts felt by nearby turbines.
Since overloading the turbine slows it down, and the blades are no longer as efficient, it is possible with an intelligent controller to brake the turbine without a dump load, slowing it down and extracting less power. If the controller is near enough to the motor
it can generally stop the blades from spinning completely if needed. The output power will gradually decrease with wind speeds increasing over say 30 knots (depending on design and settings) unlike some turbines (like air-x) which stop and restart in high winds and continuing to output some power.