Design of filter for ISO pulses in automotive design

Thread Starter

Shashwat97

Joined Apr 15, 2019
18
Please help me with designing a filter of ISO pulses especially Pulse1,2,3. I need detailed calculation and selection procedure for the same.
Thanks in advance
PS: This s/m is for 24V operation.
 

wayneh

Joined Sep 9, 2010
17,152

Thread Starter

Shashwat97

Joined Apr 15, 2019
18
Yes, but I doubt that many of the experts here that might help you are familiar. They can't help you if they don't know what you're asking for.
Ok, actually these are the pulses defined by ISO which can appear on battery line of my system. Now to protect my system against them I need to have EMC filter to reduce conducted emissions mostly these filters are pk filter but I want to know exactly how to design them how to select caps and inductor values
 

Papabravo

Joined Feb 24, 2006
16,107
I could probably do it, but I'm not motivated to acquire and understand the ponderous ISO documentation. I literally have zero incentive to help in that regard. If the TS can specify any of his requirements in concise and succinct form I'd be happy to point him in the correct direction. For example:
  1. Active or Passive filter
  2. Location of the passband, transition band, stopband, and required attenuation for each
  3. Any phase or group delay requirements
Those are things I can work with, the rest of that standards bumpf is worthless for design purposes. It is useful for verification however. It defines what done means.
 

Marc Sugrue

Joined Jan 19, 2018
213
Please help me with designing a filter of ISO pulses especially Pulse1,2,3. I need detailed calculation and selection procedure for the same.
Thanks in advance
PS: This s/m is for 24V operation.
Ok, actually these are the pulses defined by ISO which can appear on battery line of my system. Now to protect my system against them I need to have EMC filter to reduce conducted emissions mostly these filters are pk filter but I want to know exactly how to design them how to select caps and inductor values
The process will be something like this.

1. Identify your conducted emissions specification and the applicable limits to your design
2. Identify the circuit//impedance of the LISN used to do the conducted emissions as this will help identify the optimal topology for the filter approach.
3. Measure your circuits emissions at Minimum, Maximum and Nominal load at high and low line using the LISN identified in 2 above. This allows you to gauge the worst case emissions for compliance against number 1. This will determine the amount of attenuation/insertion loss you require and at what frequencies. Also worth noting your peak currents at the fundamental switching frequency unless you already know it as this current is your load impedance for the filter design.
4. Once you've specified the above details you can select the apropriate filter topology to get the attenuation you require which will deal with immunity also. Typical examples of filters used for EMI are PI or LC filters, often these are multi stage to achieve bandwidth or attenuation
 
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