CRM Boost PFC Circuit Conducted EMI Analysis and Suppression

The purpose of this article is the CRM Boost PFC circuit, which analyzes the conducted electromagnetic interference of the converter. It mainly introduces: the converter's conducted EMI noise source, including MOS switch drain source voltage VDS, gate drive signal voltage overshoot, rectifier bridge noise generated by diode and transformer magnetics. An equivalent model of the gate drive circuit is established. The cause of the noise is analyzed and the corresponding suppression measures are proposed. This article builds a low power 100W CRM Boost PFC prototype and uses the R&S EMI receiver ESU26 to perform EMI noise tests on prototypes. EMI caused by overshoot of the drive voltage is analyzed and the voltage overshoot is suppressed by adding capacitance between the power supply terminals of the DC power supply of the control chip.