Susceptibility of Optocoupler to Conducted EMI

To investigate the response patterns of the optocoupler to conducted electromagnetic interference (EMI), a conductive susceptibility experiment was carried out using direct injection method. With single-frequency continuous signals injection, the frequency-domain response of the ‘on-off’ transition threshold of the optocouplers is measured. With the Amplitude-Modulated (AM) signals injection, the results show that at very low frequencies(<1MHz), the output of the optocouplers follows the change of the interference signal, while at higher frequencies the output of the optocouplers follows the envelop of the interference signal and neglected the detailed oscillation in the waveforms. The susceptibility behavior of optocouplers to interference signals varies with different frequencies. This variation is significant for analyzing the electromagnetic susceptibility of control circuits that use optocouplers as their core components.