新能源与储能系统里，高压动力线束旁边往往就是低压信号线。高压回路快速的开关动作（电机控制器PWM）会向外辐射干扰，屏蔽没做好，整车/整机EMC测试就过不了。本文讲清三种主流屏蔽结构的取舍逻辑。
In EV and storage systems, HV harnesses run next to low-voltage signal lines. Fast PWM switching radiates interference; poor shielding fails EMC. Here is how to choose among three mainstream shield structures.
1. 铝箔屏蔽：性价比之选1. Aluminum foil: the value choice
铝箔（绕包或纵包，常见厚度0.025-0.05mm）对高频电场屏蔽效果好，成本低、柔软度好，是消费级与一般工业线束的主流选择。短板是机械强度低、搭接电阻不稳定，通常需配一根引流线（地线）保证屏蔽层连续导通。
Foil shields block high-frequency E-fields well at low cost and stay flexible, but are mechanically weak — usually paired with a drain wire for continuity.
2. 编织层：机械与屏蔽双保障2. Braid: shielding plus mechanical strength
镀锡铜编织层（覆盖率常见85%-95%）低频磁场屏蔽与机械保护都更强，抗拉抗磨，适合车载高压、频繁振动的场合。代价是成本约为铝箔方案2-4倍、弯曲半径变大。高压大电流场景（充电桩、电池包动力回路）推荐至少在干扰源侧使用编织屏蔽。
Tinned-copper braid (85-95% coverage) adds low-frequency magnetic shielding and mechanical strength for vibrating on-board HV runs, at 2-4x cost. Recommended on the interference-source side of HV circuits.
3. 铝箔+编织组合：EMC严苛场景的标配3. Foil + braid combo: for tough EMC
组合结构覆盖全频段，是车规高压线束的主流（如屏蔽层覆盖率≥90%编织+内层铝箔）。成本最高，但面对CISPR 25等车规EMC限值时几乎不可省。
Foil plus braid covers the full spectrum and is standard for automotive HV harnesses facing limits like CISPR 25.
4. 容易被忽略的三件事4. Three commonly missed points
一是屏蔽层接地方式：单端接地防低频、双端接地防高频，按干扰特征定；二是端接处的"屏蔽连续性"——连接器壳体360°环接才能保住屏蔽效果；三是高压线与信号线分槽走线，物理距离永远是最便宜的屏蔽。
Ground single-ended vs both ends by interference type; keep 360° shield termination at connector shells; and route HV away from signal lines — physical distance is the cheapest shield.
写在最后Final words
屏蔽方案的本质是"在EMC测试限值和成本之间找最低解"。沐元达按客户EMC目标反向推荐屏蔽结构，欢迎把系统情况发给我们评估：18407551752 / eric@muyenda.com。
Shielding is about the lowest-cost structure that passes your EMC limits. Send us your system targets: +86 184 0755 1752 / eric@muyenda.com.