What role does EPS soft switching play in improving EMC?

Employing soft-switching technologies (such as ZVS zero-voltage switching and ZCS zero-current switching) in EPS can significantly improve EMC performance. The core principle is to enable power switching devices to turn on when the voltage is zero (ZVS) or turn off when the current is zero (ZCS), theoretically eliminating voltage and current overlap during hard switching and drastically reducing the dramatic switching voltage and current changes (high dv/dt, di/dt) and their accompanying high-frequency noise.

Therefore, the conducted and radiated EMI spectrum energy of soft-switching EPS topologies, especially at the switching frequency and its harmonics, is significantly lower than that of hard-switching topologies. This simplifies the design of output filters, reducing their size and cost. However, soft-switching circuits are generally more complex, increasing control difficulty, and often only achieve ideal soft-switching conditions within specific load ranges, requiring a comprehensive trade-off between efficiency, complexity, and EMC.