Specific operating steps for new energy vehicles in collision tests and water wading tests

Crash test

Vehicle collision types are divided into head-on collision, side collision, rear-end collision and dynamic rollover (platform rollover, spiral rollover, slope rollover, sand rollover, curb rollover test, etc.).

Head-on collisions are the most common traffic accidents, causing the greatest harm to drivers and passengers, followed by side collisions, and rear-end collisions are less harmful. Regardless of head-on collisions, side collisions, or rear-end collisions, although the test conditions are different, the electrical safety evaluation indicators for electric vehicles after a collision are basically the same.

Specification for post-crash safety evaluation of electric vehicles

After an electric vehicle collides, three types of tests are required, including electrolyte leakage, REESS (onboard rechargeable energy storage system) movement, and anti-electric shock protection.

Electric vehicle post-collision electrical safety test items and requirements

The high-voltage wiring harness assembly after the vehicle collision test should meet the following requirements:

1

Low voltage requirements

Measure the voltages at V1, V2h and Vb within 5 to 60 seconds after the collision. The voltage values ​​of the three should not exceed 30V AC or 60V DC.

Low voltage calculation diagram

2

Low power

Between 5 and 60 seconds after the collision, Vb and Ie are measured simultaneously, and the product of voltage and current is integrated during this period, or Vb, V1 and V2 are measured at a time point during this period and calculated based on the capacitance value C. It is required that the total electric energy TE on the high-voltage bus should be less than 0.2J, and the energy stored in the capacitor should also be less than 0.2J.

Low power calculation diagram

3

Physical protection

To prevent electric shock injuries caused by indirect contact, the high-voltage wiring harness is required to be tested with a current greater than 0.2A . The resistance between all exposed conductive parts and the electrical platform should be less than 0.1Ω. When the electrical connection is welded , this requirement must also be met. (The design of the equipotential wiring harness is to effectively prevent electric shock injuries caused by indirect contact).

4

Insulation resistance

If the power system consists of independent DC and AC buses, the AC high-voltage bus and the DC high-voltage bus are insulated from each other. The insulation resistance between the high-voltage bus and the electrical platform should be a minimum of 100Ω/V for the DC bus and 500Ω/V for the AC bus (for example, the high-voltage bus used by the drive motor , PTC , and air conditioning compressor ).

If the power system consists of connected DC and AC buses, the DC and AC buses are mutually conductively connected, and the minimum insulation resistance between the high-voltage bus and the point platform should be 500Ω/V. If the protection level of all AC high-voltage buses reaches IPXXXB after a vehicle collision, or the AC voltage is ≤30V, the minimum insulation resistance between the high-voltage bus and the electrical platform should be 100Ω/V working voltage (for example, the high-voltage bus used by chargers and power electronics ).

C-NCAP requires that the insulation resistance of the DC high-voltage busbar be no less than 100Ω/V, and the insulation resistance of the AC high-voltage busbar be no less than 500Ω/V; FMVSS requires that the insulation resistance cannot be lower than 500Ω/V.

Water wading test

For specific water-crossing standards for electric vehicles, please refer to the contents of Section 1.2.15.5(2) "Definition and local standards of the height of the vehicle's water-crossing line".

Different from the vehicle sealing test, the main test object of the vehicle wading test is the performance characteristics of the electrical components installed in the area below the vehicle wading line. The high-voltage electrical system including the high-voltage wiring harness must meet the following requirements:

1

Personnel electric shock protection

2

Insulation resistance requirements

3

Withstand voltage requirements

4

Waterproof sealing requirements.

Power Batteries are usually placed under the vehicle. When the road surface is flooded, the battery pack may be soaked or impacted by water. The waterproofing of the battery pack and its external equipment (high-voltage charging harness, etc.) is particularly critical.

After the wading test is completed, check whether the high-voltage system of the vehicle is working properly. Remove the high-voltage wiring harness assembly from the test vehicle. After the insulation resistance and withstand voltage tests , perform a destructive test and wipe the connectors /distributors/rubber parts with test paper . No water marks/water vapor are allowed in any high-voltage parts, and no corrosion such as copper green is allowed at the terminals and wire crimpings.

In general, the nature of the vehicle wading test and the vehicle sealing test are similar, but the parts they focus on are different. For high-voltage wiring harnesses, especially those installed in the chassis area of ​​the vehicle, the results of the vehicle wading test are a supplement and reconfirmation of the vehicle sealing test results.

High-voltage wiring harness assembly mass production inspection

Of course, in daily production, it is impossible for us to complete the above tests on all high-voltage wiring harness assembly parts. The above tests are only used to check whether the design of the high-voltage wiring harness parts after installation on the vehicle meets the standards and requirements.

In daily production, the routine inspections that need to be completed for high-voltage wiring harness parts include incoming material inspection, production inspection, and finished product inspection. It should be noted that the routine inspections mentioned in this chapter are based on the perspectives of wiring harness assembly suppliers and vehicle manufacturers.

Incoming material inspection

Production testing

Finished product testing

Other requirements

Other special requirements for automotive high-voltage wiring harnesses need to be additionally confirmed by the OEM.

Taking recyclability requirements as an example, there are national standards "GB/T 26988 Recyclability Labeling of Automotive Parts" and "GB/T 19515 Calculation Method for Reusability and Recyclability of Road Vehicles"; international standards "ISO 22628 Road Vehicles - Reusability and Recoverability - Calculation Method" and "EC Type Approval on Reusability, Reusability and Recyclability of Vehicles and Amendment to EEC".