RPM sensor for Wind Turbine
Monitoring the rotational speed of the wind turbine blades can help with power performance measurements.
This post shows various techniques to measure the rotational speed of a ‘wild AC’ output small wind turbine. In this system, the wild AC is rectified into DC and either delivered to a battery or to a grid-connected inverter.
The wild AC output of the turbine can be used to give us the rotational speed.
The AC waveform can be converted into a digital signal by a circuit such as this, from Noam Dotan of Comet Me:
This circuit includes opto-isolation, which means the data logging system is protected from any over-voltage.
The fuse protects from any short circuit and only needs to be a low value, 50-100mA.
The zener diode limits to voltage across the LED of the opto-isolator.
The output will be a digital on/off signal for every time the magnet passes the coil. As mentioned, the number of magnets can be used to calculate the actual RPM of the rotor.
The LM7805 is a voltage regulator to give a constant voltage – the power supply of the data logger can be used here instead.
RPM sensor for Wind Turbine