One Stop Electrical Reference Centre

Make your own single or multi phase bridge rectifier from diodes

The electricity generated by most wind turbine generators is alternating current (AC). To use this to charge batteries or power most lighting and devices directly, it must be rectified into direct current (DC).

The simplest bridge rectifier is made up of just four diodes (components which allow electricity to flow in just one direction).

Three Phase Bridge Rectifiers

Typically wind turbines do not generate single phase AC (displayed in the above example), but instead generate multi-phase AC - usually three-phase AC electricity.

Therefore, more diodes are required to rectify the three phases of electricity - in fact six are required and must be wired up as shown in the diagram below.


Why Make Your Own Bridge Rectifier?

It is possible to purchase complete bridge rectifiers cheaply with current ratings from below 1 Amp to as much as 35 or 50 Amps.

To make a three phase bridge rectifier is a simple case of wiring them together and then to each of the three phases of generated electricity.

Pictured above is an example of a 35A bridge rectifier. Bridge rectifiers rated above 35A or 50A suddenly become very expensive. Therefore if your wind turbine has a total maximum output current of more than 25-30 Amps, it is worthwhile making your own bridge rectifier with high power rated diodes wired as shown above but fitted to a suitably large heatsink.

Find out more about bridge rectifiers.

For most alternative energy applications, we require a direct current (DC) voltage to be generated - for example to charge a bank of batteries. However wind turbines and wave power generators create an alternating current (AC) voltage.

This is where the Bridge Rectifier comes in. The AC voltage generated is passed through a circuit of four diodes arranged as shown below and emerged converted into a more useful DC output.

Diodes allow electricity to flow in only one direction, but there is a small voltage lost across the a diode of 0.7V called the forward voltage drop.

If the diode is wired in the wrong direction then no current (actually a very tiny current) flows across the diode. However, if the voltage is too high and goes over the diode's maximum reverse voltage, the diode will breakdown and fail.