How to ensure EMC of EPS under high and low temperatures?

To ensure stable EMC performance of EPS over a wide temperature range (e.g., -20°C to +55°C or wider), the impact of temperature on component and material characteristics must be considered. Key points:

1. Component temperature characteristics: The permeability and losses of magnetic components such as common-mode inductors change with temperature; the capacitance and ESR of capacitors also drift; the characteristic curves of filters shift. Materials with stable temperature characteristics (such as NPO capacitors, wide-temperature ferrites) should be selected, or sufficient performance margins should be ensured in the design to withstand extreme temperatures.

2. Shielding materials and connections: The elasticity and conductivity of shielding materials such as conductive pads and springs change with temperature. Wide-temperature products (such as silicone rubber coatings) should be selected. Metal seams may affect contact continuity due to thermal expansion and contraction.

3. Device operating point variations: Temperature affects the switching characteristics and on-resistance of semiconductor devices, potentially altering the noise spectrum.

4. Thermal design assurance: Good thermal design ensures that all components operate within their allowable temperature range, which is fundamental to stable performance. EMC testing under high and low temperature environments is necessary to verify the robustness of the design.