Does the lack of an EMI filter on the power module of the BMS control board cause conducted interference to exceed limits?

The absence of an EMI filter in the power supply module greatly increases the likelihood of conducted interference exceeding limits. The power supply module itself is a primary noise source, generating wideband differential-mode and common-mode noise during switching. Without a front-end EMI filter, this noise will be directly conducted to the input power lines. A basic EMI filter typically includes a common-mode inductor, a differential-mode inductor, and X and Y capacitors, which work together to attenuate noise in specific frequency bands. Omitting this filter means losing the most direct and effective means of noise suppression, making it difficult to pass conducted interference tests. Therefore, equipping the power supply module with a suitable EMI filter is a fundamental prerequisite for meeting EMC standards.