Pre-charging resistance in new energy power battery and vehicle high-voltage electrical system appli

Pre-charging resistance in new energy power battery and vehicle high-voltage electrical system applications

1. Calculation of sink cross section

2.Requirements for temperature rise of conductors and electrical parts

According to the forthcoming Technical Requirements for High Voltage High Current Wire Harnesses and Connectors for Electric Vehicles.

6 Physical Properties

6.1 Temperature rise

When the high-voltage connection system is connected in normal operation, the temperature rise at each point of the system should not be more than 55K, and there is no damage that affects the performance of the product.

9 Test Methods

9.5 Temperature rise

According to GB/T 5095.3-1997 in the test 5a requirements of the normal operation of the high-voltage connection system temperature rise test, the test does not contain interlocking signal terminals. The test current is the rated current value of the system, and the test time is shown in Chapter 22 of GB/T 11918.1-2014.

Note: The rated current is the design value of the normal working current of the high-voltage connection system.

3.Shielded and Unshielded Applications

Shielded wire is a transmission line that uses a metal mesh braid to wrap the signal line, the braid is usually red copper or tinned copper. The effect of the shielding layer is not mainly due to the metal body itself on the electric field, magnetic field reflection, absorption, but due to the shielding layer of the grounding generated, the grounding of different forms will directly affect the shielding effect.

The thickness of the shielding layer exceeds 38μm, so that the frequency of electromagnetic interference that can enter the cable through the shielding layer is mainly below 5MHz. Low frequency interference below 5MHz can be effectively counteracted by applying the principle of twisted pair balancing.

Away from the source of interference is the simplest anti-interference method, if the CAN line and the strong power interference source away from 0.5 meters, the interference will be basically unaffected. To solve this problem, we can only try to ensure that the strong power and weak power separate bundles, distance as far away as possible. It is impossible to avoid, but also to cross vertically, nor parallel wiring.

3.MSD/RELAY/LEM Selection

5.Interpretation of electrical schematics