Fisher and Paykel Generators/Alternators.
When you get an unmodified smart drive it is capable of generating from 0 to 300 Volts depending on the speed and is wired to produce 3 phase AC in a star configuration. Below we'll find out what all this means and how to change it to produce what we require.
So lets look at some key points on how it is originally. It has 42 coils of wire around the edge of the stator. If you trace the wiring you will notice that there are two "ends". At one end three wires are join together and at the other end the three wires come out separately. This is what is know as wiring in a star configuration (the other option being a delta configuration which we will get into later). So there three wires going in, each wire connects 14 coils in parallel to the end point where all the wires join together. Each of these groupings of 14 provide different current flows at different times, each providing AC power but each one out of sinc (or phase), thus it is described as 300 volt, 3 phase AC generator.
First of all we need to decide what voltage we want to convert it to. Most people either want to 12 or 24 volts. If you have a look at at the above diagram you can see that there are 3 sets of 14 individual coils. Each individual coil is capable of producing about 21 volts at full speed so 14 wired in series are capable of producing about 300 volts (14*21). So for a 12 volt system it is a good idea to join them in sets of two, producing up to 40 volts, because we can get at least 12 volts at lower speeds. Then, wire these in parallel to increase the amps. (have a look at our electricity basics page for the effects of wiring in parallel or series).
So that's the theory. Let's do it to a real one. Click on any of the images for a larger version.
On the next page we will look at a few wiring options.