Matters needing attention in the design of high-voltage wiring harness for new energy vehicles

China [CN]

The new energy vehicle high-voltage wiring harness carries the internal and external wiring harness connections of the vehicle, distributes power through the power distribution box, transmits power efficiently and high-quality, and shields external signal interference. It is the neural network of the high-voltage system of new energy vehicles. Electronic components, transmitting power and data, provide a guarantee for the reliable operation and safety of new energy vehicles.

1. Voltage requirements for high-voltage wiring harnesses

New energy vehicles generally work in the B-level voltage range, so the high-voltage wiring harness is required to meet the working voltage range requirements of 60V-1500V. The current general wire voltage requirements are AC30V-1000VRMS according to GB/T 184384.3. Or DC60V-1500V.

2. Current requirements of high-voltage wiring harnesses

As the main energy transmission channel, the high-voltage wiring harness of new energy vehicles needs to withstand a large current, and the rated working current of the DC bus can reach more than 200A.

3. Requirements for sealing of high-voltage wiring harnesses

Since the high-voltage wiring harness carries large voltages and large currents, its tightness is also very important. Generally, it needs to pass the waterproof and dustproof test and air tightness test. The sealing effect of the whole component is not good, which will cause moisture or water ingress, which will cause the wires to be easily damaged and aged. High probability of failure.

4. Requirements for high-voltage wiring harnesses on EMC performance

EMC (Electromagnetic Compatibility) includes EMI (Electromagnetic Interference) and EMS (Electromagnetic Susceptibility), and refers to the ability of a device or system to operate compliantly in its electromagnetic environment without causing intolerable electromagnetic interference to any equipment in its environment.

For new energy vehicles, it is first necessary to ensure that each component meets the requirements of EMC standards, because the wiring harness connects the various control units together.The key points of the shielding design of the new energy vehicle are the layout of the high-voltage system, the shielding design and the anti-interference processing of the CAN communication network.First of all, try to require the high-voltage wiring harness to be arranged along the body to optimize the electromagnetic radiation loop of the whole vehicle, and at the same time use the body to form a closed shielding cabin.At the same time, shielding high-voltage cables and connectors is also an effective method to reduce unnecessary electromagnetic interference.It has been verified through a series of standard experiments that shielded cables and connectors can effectively reduce unnecessary interference in the frequency range of 100 kHz to 200 MHz.

5. Requirements for safety performance of high-voltage wiring harnesses

The safety design of the high-voltage wiring harness mainly lies in the insulation, withstand voltage protection, overload, IP level protection requirements of the connectors, etc.

1) Insulation: The insulation selection of electrical lines and equipment must be matched with the voltage level and the use environment and operating conditions to ensure the safety of the insulation.

2) Withstand voltage protection: apply a voltage higher than the normal working voltage to the insulator of the device under test for a period of time.If the insulation is good enough during the period, the voltage applied on it will only generate a small leakage current.If a device under test insulator maintains its leakage current within a specified range for a specified period of time, it can be determined that the device under test can operate safely under normal operating conditions.

3) Overload: The amount of current that is allowed to pass continuously in the electrical line without overheating the wire, which is called the safe current carrying capacity or safe current.The high-voltage cable carrying current cannot exceed the safe current.

4) IP protection level: In order to ensure the safety of the entire vehicle, the protection level of all high-voltage plug-ins is required to be at least IP67 or above.

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