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Overview of High Voltage Wiring Harness for Electric Vehicles

Date:2022/3/31 7:04:10

Electric vehicle high-voltage wiring harness distribution:

1. Power battery high voltage cable, connect the power battery to the high voltage junction box

2. Motor controller cable, connect the cable from the high voltage junction box to the motor controller.

3. Fast charging cable, the cable connecting the fast charging port to the high-voltage junction box

4. Slow charging cable, the cable connecting the slow charging port to the car charger

5. High-voltage accessory wiring harness, connect the high-voltage junction box to the wiring harness between DCDC, vehicle charger, air conditioner compressor, and PTC

High voltage wiring harness design requirements:

1. In the high-voltage system design, the DC high-voltage circuit must strictly implement the dual-rail system (that is, the body cannot be used as the ground like in the low-voltage line).

2. The circuit of the entire high-voltage wiring harness is shielded and connected. Domestic OEMs usually use shielded high-voltage cables. Shielded high-voltage cables can reduce the impact of EMI (ElectroMagnetic Interference) and RFI (RF Interference) on the vehicle system. The shielding layer of the high-voltage wiring harness of the interfaces of the motor, the controller and the battery is connected to the housing of the motor controller through a crimping structure such as a plug-in, and then connected to the body ground.

3. Withstand voltage performance: 600/900VAC 1000/1500VDC.

4. Current resistance: According to the current of the high-voltage system components, it can reach 250~400A.

5. Temperature resistance: high temperature resistance grades are divided into 125℃, 150℃, 200℃, usually choose 150℃ wire; low temperature conventional -40℃.

6. Generally use thick-walled wire (wall thickness 0.6~1.1mm)

7. Design of wire diameter:

The following factors need to be taken into consideration

① Rated current value of load circuit

② Allowable temperature of wire conductor

③ The ambient temperature around when the wiring harness is working

④ The energization rate decreases due to the temperature rise when the wire itself is energized

⑤ Reduction factor for allowable current of bundled wire harnesses

Verification formula: allowable current value of wire × reduction of energization rate caused by ambient temperature × reduction coefficient caused by bundling > rated current value

Wire layout requirements


1. The arrangement of high-voltage components should leave enough buffer space for the power source and related components on the transmission path, and increase the distance between the high-voltage components and the vehicle body as much as possible to ensure that any non-external high-voltage components The minimum size of the vehicle outline is kept above 110mm;


2. Avoid crossing and winding between high-voltage wire harnesses. The positive and negative high-voltage wiring harnesses should be routed along the same path, and the distance of bifurcation should be avoided or shortened as much as possible;


3. The gap between adjacent parts should be ≥15mm, and the dynamic gap should be ≤25mm;


4. Due to the material and diameter of the high-voltage line, there should generally be fixed points at the front and rear ends of the bend to avoid a large deviation between the actual direction and the design direction;


5. The influence of factors such as vehicle scraping and sand splashing on the high-voltage wiring harness should be fully considered;


6. The high-voltage wiring harness should avoid sharp edges. If it is unavoidable, corresponding protective devices should be added to the sharp edges such as through holes, as shown in Figure 4.


7. The bending radius of the wiring harness should be ≥6D (D is the diameter of the high-voltage wiring harness);


8. The ambient temperature should be lower than 125℃;


9. The gap between two adjacent fixed points should meet the following requirements:


a. The cross-sectional area of ​​the high-voltage wiring harness is more than 16mm2, and the gap between the two fixed points is less than or equal to 300mm;


b. The cross-sectional area of ​​the high-voltage wiring harness is less than 16mm2, and the gap between the two fixed points is less than or equal to 200mm;


To learn more about EV cable  and EV charging cable, please visit OMG's official website: https://www.omgevcable.com/

Overview of High Voltage Wiring Harness for Electric Vehicles