Senior automotive engineer talks about EMC design and rectification

Zhou Yan brothers gave me a piece of material. I made some rectifications on this basis. This article is the integration of our two materials. Everyone doing EMC experiments to the experimental toss is very painful, the actual cost.

The situation of domestic recourse is more of a direct and bad situation. This is a bad situation that everyone can understand.

Case 1

– A medium to high-end sedan with a high-performance ABS system. The prototype encountered a rainy day in a live test and started the wiper. At a certain speed, ABS suddenly lost its effect.

– consequences, vehicle damage

Case 2

– A certain type of domestically produced micro-car, its generator regulator often appears to be easily damaged by breakdown

– After investigation, this damage is likely to occur when the wiper is working.

The main cause of this phenomenon is the wiper. The wiper drive motor acts as an inductive load. When the power is cut off, reverse current is generated and transmitted to the power supply system through the power line, thereby generating interference pulses in the power system. Some electronic components cannot work normally under such interference pulse conditions. It even caused damage.

Case 3

– A certain domestically developed airbag suddenly detonated on the vehicle assembly line

– After testing the electronic ignition controller of the airbag, it was found that it could not withstand strong environmental electromagnetic fields. When an electrostatic discharge occurred, it would malfunction.

Analysis results: the body of the workers at the scene of the electrostatic discharge of the airbag

The following is the way to bury the pit to the engineer of the vehicle company. The wiring is actually going to the ECU and the following situation occurs.

So in general, we are designing first:

Board-level grounding strategy, combined with EMC specifications

System level grounding and protection

Here is the combination of the concept level and the block level.

1) Schematic stage

Distinguish between the module has a weak sensor signal, a common small current signal, a large current output drive, and a high current inductive load drive.

For low-side drive, the return path of the signal is returned through the ground of the module;

The high-side switch draws current through the power supply of the module. Based on these characteristics, we basically group the circuits.

The implementation here also needs to be implemented and considered later.