Application of Optocoupler Isolation in Rotation Speed Measuring Circuit of Maglev Blower

The main helium fan of a high-temperature gas-cooled reactor uses a magnetic bearing as a shaft bearing, whose pulse signal of rotation speed could be easily disturbed by a high-power variable-frequency drive. There are also problems such as strong electromagnetic interference, potential safety hazards, and different potential distribution between strong and weak electric circuits. Moreover, analog signals require step-down to match digital signals when using AD conversion to transmit signals. This study uses optocoupler isolation to match voltage and improve the transmission quality of rotation speed signal without changing the circuit. Tests and verification have been done on the test maglev blower. The results show that under the same conditions, compared with no isolation, the application of optocoupler isolation is reliable and effective. The application of this technique provides a reference for voltage regularization and enhances the anti-interference ability of analog signal transmission in a complex electromagnetic environment, like maglev blowers.