Capacitive and Inductive Coupled EMI model

AI Thread Summary
The discussion focuses on creating a circuit schematic that effectively represents both inductive and capacitive coupling paths for EMI modeling, particularly from a MOSFET switching on a DC bus to nearby circuits. The user has extracted parasitics and has separate netlists for capacitive and inductive coupling but seeks guidance on combining them into one model. Suggestions include defining nodes on the EMI generator and sensitive target to create a scattering matrix, as well as using transformers to simulate induced currents. The conversation emphasizes that shared impedance coupling may dominate crosstalk and that further analysis could benefit from reviewing the schematic and layout. Overall, combining both coupling types in a single model is considered advantageous if the loads and sources are accurately represented.
newengr
Messages
21
Reaction score
0
TL;DR Summary
I would like to create an EMI equivalent circuit model considering both inductive and capacitive coupling in one.
I am new to EMI modeling and just looking into it. I would like to create a circuit schematic to represent the inductive and capacitive coupling paths in one schematic. All that I've been able to find online is references discussing each independently. Is this the best approach if you want to consider both? Any references or suggestions for modeling both together would be helpful. Or if there's a reason not to, that would be helpful too.
 
Engineering news on Phys.org
We need a little more information.
What is the source of the EMI ?
What is the target ?

Directional couplers and short antennas can be hard to express on a circuit schematic.
 
The source of the EMI is a MOSFET switching on a DC bus. The target are nearby circuits referenced to a the midpoint of the bus or the -DC rail; both cases work. I extracted the parasitics which include capacitive coupling and inductive coupling terms using Q3D. I have the netlists for capacitive and inductive separate so I can draw the circuit for each. The challenge for me is trying to combine them.

I think combining them would be best if I can model my loads and source well enough. Then my circuit would have the appropriate voltage and current waveforms. Or is it better (or equivalent) to just take my voltage waveform and use it to analyze capacitive coupling the use my current waveform to look at inductive coupling? O and I'm neglecting radiated coupling at this point.
 
What form does the mutual C and L data take.
Does it employ nodes similar to a spice model?

If you can define the nodes on the EMI generator, and the nodes on the sensitive target, then you might define a scattering matrix that combines the reactive currents being delivered to the target.
Induced currents would appear between two nodes and could be simulated using transformers with coupling coefficients. Capacitive currents due to voltage changes would be between nodes. The method of moments might be considered.

I don't think EM radiation will be important for such a small space. It will all be near field.
 
newengr said:
The source of the EMI is a MOSFET switching on a DC bus. The target are nearby circuits referenced to a the midpoint of the bus or the -DC rail
Probably shared impedance coupling will dominate the crosstalk, but without seeing your schematic and layout, it's hard to know. Can you share the schematic and layout?
 
I used to be an HVAC technician. One time I had a service call in which there was no power to the thermostat. The thermostat did not have power because the fuse in the air handler was blown. The fuse in the air handler was blown because there was a low voltage short. The rubber coating on one of the thermostat wires was chewed off by a rodent. The exposed metal in the thermostat wire was touching the metal cabinet of the air handler. This was a low voltage short. This low voltage...
Hey guys. I have a question related to electricity and alternating current. Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz. How would appliances be designed, and what impact would the lower frequency and voltage have on transformers, wiring, TVs, computers, LEDs, motors, and heating, assuming the laws of physics and technology are the same as on Earth?
Thread 'Electromagnet magnetic field issue'
Hi Guys We are a bunch a mechanical engineers trying to build a simple electromagnet. Our design is based on a very similar magnet. However, our version is about 10 times less magnetic and we are wondering why. Our coil has exactly same length, same number of layers and turns. What is possibly wrong? PIN and bracket are made of iron and are in electrical contact, exactly like the reference design. Any help will be appreciated. Thanks. edit: even same wire diameter and coil was wounded by a...
Back
Top