How to handle EMC testing for multiple EPS units in parallel?

When multiple EPS units are operating in parallel, EMC testing must be performed, treating the parallel system as a single entity. Key testing points:

1. Test configuration represents the worst-case scenario: Testing typically involves all units operating at full load simultaneously. The maximum interference that may result from noise superposition must be considered.

2. Pay attention to circulating current and resonance: Circulating current between parallel units may generate new differential-mode and common-mode noise frequency components. The system impedance and grid impedance may form new resonance points, which need to be observed during testing.

3. Unified grounding system: During testing, all parallel EPS units should be connected to the ground through a common grounding busbar to simulate a typical installation scenario.

4. Standardized cable layout: Input and output cables should be bundled and laid out according to typical installation methods, as coupling between cables can affect the results.

5. Standard reference: The system equipment must be tested according to the product standards (such as GB4824). The interaction effects of parallel operation must be considered during the design phase, for example, by using interleaved modulation to disperse harmonics, optimizing the parallel busbar design, and ensuring good grounding of each unit.