Analysis of shielding structures commonly used in high-voltage wiring harnesses for new energy vehicles

At present, new energy vehicles are developing towards high voltage and high current. Some high-voltage systems can withstand voltages as high as 800V and currents as high as 660A. Such large currents and voltages will generate electromagnetic radiation, which will interfere with the normal operation of other electronic components. , so the electromagnetic interference problem must be considered in the design of the high-voltage wiring harness. There are three commonly used methods of shielding electromagnetic interference for high-voltage wiring harnesses, namely: ①The wire has its own shielding layer; ②Add a shielding sleeve outside the wire; ③Shield from the source and directly add a filter to the high-voltage equipment.

Conductor with self-shielding layer

Figure 1 is a schematic diagram of the structure of a single-core high-voltage conductor with its own shielding layer. This kind of conductor is usually composed of two layers of metal conductive materials and two layers of insulating materials. layer. The wire core is generally made of copper or aluminum, which is the carrier of the current. When the wire core has current passing through it, electromagnetic interference will be generated, and the function of the shielding layer is to shield the electromagnetic interference, so that the electromagnetic interference starts from the wire core and ends at the shielding layer. Emitted to interfere with other electronic devices.

At present, the common shielding layer structure can be divided into three situations, namely: 

①braided shielding plus metal foil; 

②single braided shielding; 

③single metal foil shielding.

The above methods are all designed for high-voltage wires with their own shielding layer. From the perspective of cost reduction and optimization of connector design and wiring harness production process, the shielding layer of the wire itself can be removed directly, but for the entire high-voltage system, EMC has to be considered, so it is necessary to add shielding in other places. components. At present, the commonly used solutions for high-voltage wire harnesses are to add shielding sleeves outside the wires or add filters to the equipment.