I need to determine the rotation speed a wind turbine generator. To do this i'd like to measure the frequency of the three-phase signal provided by the PMG generator
The three-phase signal tension range is 0V - 300V and the frequency range is 0-70Hz.
i use stm32 microcontroller to compute the frequency so i need a 0-3.3V square shape signal input.
I designed a circuit to turn the AC signal into a squared shape 3.3V signal:
I send one phase of the generator to a rectifier 1n4007 diode to remove the negative tension. Then a 3.3V zener clip the signal. The opto-isolator protect the stm32 from high tension and create a beautiful 3.3 square shape signal
question: is it safe, is it reliable ?
Thank you !