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Relationship between idc, iac, occurlim

Posted: Wed Sep 30, 2020 10:04 am
by Peter
Hello Forum. Would it be possible to explain the relationship between the above please? I ask because I can measure peak DC current from the battery which shows 185A but I have occurlim now set to 1200 to stop shutdown under quick acceleration. I am concerned the current at the igbt's is 1200A ! I calibrated the LEM current sensors using a know load and adjusted the calibration factor accordingly so I am wondering why occurlim has to be set so high. Oddly when I do get a shutdown (shutting down to precharge ON to allow quick reset if this happens whilst on the road) I do not get any error messages, I used to see overcurrent limit or encoder errors early days but they do not appear with shutdown. Thanks for your help and advice. Peter

Re: Relationship between idc, iac, occurlim

Posted: Wed Sep 30, 2020 1:13 pm
by johu
ocurlim is applied to momentary AC current on two of the three phases. One phase is unmonitored as an over current on one phase will also show up on one of the other phases. So if you plot il1, il2 that is the currents your limit is compared against.
IDC is calculated very roughly from dutycycle and AC current and I would expect it to read a bit higher than actual.

Encoder error message only applies to single channel encoder

Re: Relationship between idc, iac, occurlim

Posted: Wed Sep 30, 2020 2:47 pm
by Peter
Thank you Johannes. I will plot at next test. Hope you are keeping safe. Peter