Factors to consider when the DC power supply cannot pass the group pulse 2KV
High frequency common mode inductors are generally used for pulse group suppression, with single-layer winding of the inductor. The thicker the wire diameter within the allowable range, the better. For magnetic cores, nickel amorphous (can be used for * *) can be considered if conditions permit. The specific material parameters still need to be determined experimentally. In the case of insufficient detection equipment, only through a large number of experiments can suitable schemes and parameters be determined, which consumes a lot of manpower and material resources.
Generally speaking, pulse trains belong to common mode signals, and circuit design schemes and interference suppression devices need to have common mode suppression capabilities. Commonly used differential mode capacitors (such as X capacitors) almost do not suppress common mode signals
If the DC power supply end still cannot pass the group pulse 2KV, it is necessary to consider the requirements of the electric fast pulse group for the circuit board board board, wiring, device selection, etc. It tests the overall EMC performance of the circuit board, and cannot rely solely on the common mode inductance to improve the experimental level. The circuit board should have a standardized method.
For common mode inductors commonly used in switching power supplies, the magnetic core of the common mode inductor is mostly ferrite, which has a good suppression effect on small low-frequency common mode signals. However, due to its small inductance, it is wound in multiple layers, and the problem of increased parasitic capacitance after multi-layer winding makes its common specifications more suitable for EMI.
If the above still cannot be passed, please consider the following points:
The power port needs to pass through EFT, 2KV/5KHz, which is the third level requirement in IEC-61000-4-4. To solve this problem, the following steps are required:
Firstly, confirm:
1. Is there a problem with the selection of common mode inductors and capacitors?
2. Is there a problem with the PCB layout placement?
3. Is there a problem with the grounding design?
Next, consider:
1. Choose the right TVS tube
2. Add TVS tubes at appropriate locations
3. Is it okay to just add TVS tubes?
Finally, even if EFT is resolved, it is important to consider whether ESD, SURGE, DIP, RE, and other tests have been passed, and not to fall into the vortex of solving one problem causing another.
