A Robust Bypass Detection Method for LED Operating States Based on PWM Interference

In intelligent electronic applications, detecting the operating states of each device often requires a large number of sensors and occupies wireless/wired multiplexed communication resources. In addition, it is necessary to analyze the electromagnetic compatibility of the power supply cautiously and apply appropriate means to suppress interference, since electromagnetic interference generated by multiple devices can disrupt the performance of conventional sensor detection method. Especially, in the field of LED lighting, PWM is widely used in daily life to control the brightness of LEDs by adjusting the duty cycle. Several studies on PWM driving circuits for LEDs demonstrate that this dimming method will cause electromagnetic interference to the DC power supply inevitably. However, the power supply ripple generated by PWM electromagnetic interference contains the characteristics of the frequency and duty cycle of the PWM modulated signal, which determine the operating state of the LED. In this paper, we presented a robust intelligent bypass detection method based on electromagnetic interference signals for the brightness detection of multiple LEDs.