Why a DC Motor Works Great For a Wind Turbine

So you want to build a wind turbine and you are trying to decide what type motor to use? First off we need a DC motor that operates at a low RPM. The reason we want a motor at a low RPM (revolution per minute) is because most areas of the country the wind speed varies with different weather patterns and we want our wind turbine to generate at lower RPM to charge our battery bank.

Let us look inside a DC electric motor. If you have ever played with 2 magnets you probably have noticed how the opposite poles attract and the same polarity poles repel. This is the basic principle of all DC permanent magnet motors. The repelling actions are what cause motors to rotate. Usually you will find three or more magnets which make up the field of the motor. How it works is when a DC voltage is applied to the armature; the armature is the center part of the motor that rotates around a shaft, it causes a magnetic field to be produced in the armature which will start to turn the armature. The reason this happens is because the poles of are permanently mounted magnets now are repelling the armature magnets which have DC voltage applied to them. If this seems a little advanced for you I apologize because I am use to this with my electrical background. What happens now is when the applied voltage increases, the motor will repel faster increasing are motor RPM.

Now in our wind turbine you might start to see why we use a DC permanent magnet motor. Ok, what happens if we spin the motor shaft with no voltage applied? We will generate a DC voltage when connected to our motor lead wires. Now I think you see why we want to use a DC motor for our wind turbine and why we want a lower speed motor. If we can produce anywhere between 12 to 18 volts this a good start to be able to charge our battery bank.

These types of motors are becoming harder and harder to find because of the demand now for home wind turbines. Some places that you might find these types of motors can be wherever machinery is driven by a DC motor for more precise RPM control. Sometimes when machinery is replaced by newer models you can salvage the old motors. Remember to look for low RPM DC motor below 400 RPM at 12 or 24 volt. One thing also is that more field magnets a motor contains the smoother it will turn.

One thing to also keep in mind is the amperage output to your batteries is very important. This what will determine how quick your batteries will recover from a drain or use cause my electical use from your home appliances or other applications. If you have ever purchased a battery charget before you will notice the anperage rating of the charge which is also the charge rate at which your battery will be charged.