Good Luck,
Ron Adventure is just bad planning." -- Roald Amundsen
The VFD (another label is AC Drive) needs a stable DC source to feed the DC Bus inside of it.
The output of the wind turbine fluxuates in voltage ultimately based off wind speed. To create a stable DC source, one would need to feed a battery bank with the turbine output, then connect an inverter to the battery bank. The inverter would feed the stable AC input voltage to the VFD. The VFD would drive the pump. The obvious problem is all the conversions of voltage,AC to DC to AC to DC to AC causes much waste.
The best solution is to have an unconventional wind turbine that generates a high voltage DC. In the example above, it was assumed the wind turbine was a typical 48VDC unit. For the best solution, we would need to connect the turbine directly to the battery bank, and connect that directly to the DC bus of the VFD. The difficulty is the fact that for a 208 VAC VFD the DC bus must be a stable 294 VDC. The formula to convert 3 phase AC to DC is
VAC ave times the square root of 2 = VDC
I have done something similar when we made an electric car and used 24 qty 12 VDC batteries connected in series to feed a VFD controlling an AC motor.
And yes, most 5KW VFDs (round up to the next size HP...7.5HP) do have the DC bus terminals available for direct connection.---------Dean-----------[ Parent ]
The 3 phase pump motor needs the voltage and frequency ratio to match as you change speed. Meaning if you have a 208VAC motor rated at 60Hz and you wanted to run at half speed, you would feed the pump motor 104VAC at 30 Hz. At 1Hz you would feed the motor 3.47VAC.
Why not design the wind turbine to provide this exact ratio of voltage to frequency directly to the pump motor. If the wind speed is slow, you may have problems pumping against such a large head. However, if the wind was blowing hard the pump would have all the power the turbine could provide with no loss in any voltage conversions.
Because you do not want to "store" water rather than electric power this may be a way to not need the VFD or batteries all together.
Just an idea to try. ---------Dean-----------[ Parent ]
I think we can rewire the alternators to achieve higher voltages as needed. I am interested in your #2 option (turbine>battery bank>dc bus of vfd). These would need to be deep cycle batteries? If there was a way to configure the vfd to only use the amount of power that the wind turbines were putting into the bank then maybe the expensive deep cycle batteries would not be needed. Or maybe at least not as high Ah ratings. I mean, only power the pump when power is coming in, and then, only to match (slightly under) what is coming in. How would I regulate this? I guess I had been sizing the battery bank for the pump like you might size one for any other appliance, giving sufficient Ah capacity to ensure power is provided for some time when the wind isn't blowing. But there is a large reservoir for the water. Much, much less might be spent on the batteries if the pump were only to be powered when the turbine is producing, and hopefully, somehow, to match that output. That may have been obvious to everyone else!
Cheers.
1996 A Smart Controller for Wind Electric Water Pumping Systems 2000 Development and Testing of a 2-Kilowatt Wind Turbine for Water Pumping[ Parent ]
