On the use of bulk current injection for testing the immunity of CAN-bus lines

In this work, an immunity test based on the Bulk Current Injection (BCI) test procedure is simulated, with the objective to predict the radio-frequency (RF) noise currents injected into the terminations of a CAN-bus line. To this end, an accurate model of the injection probe is combined with typical injection profiles recommended by automotive Electromagnetic Compatibility (EMC) Standards, and with a distributed-parameter representation of the wiring harness. The model also includes possible imbalance affecting the bus terminal sections, whose non-ideal behavior is recognized to be at the basis of bus susceptibility to electromagnetic interference. As a matter of fact, the obtained predictions prove the great sensitivity of the injected current to the degree of imbalance of the terminal sections, and indicate that, in order to derive from the test consistent information to fix possible susceptibility problems, statistical models accounting for the uncertainty associated with the involved circuit components are preferable, unless accurate characterization of the terminal sections were available.