HEV system EMC investigation during transient operations

EMC challenges for hybrid electric vehicles have been published and shown to have dependencies on high slew rates coupled with parasitic impedances from electric machines, high voltage cables, heat sinks, circuit layout considerations, and the alike. Although the steady state operation of power converters creates apparent EMC disturbances, it doesn’t always create a worst case scenario. Transient operation of the system, such as load torque and speed gradients, can cause additional disturbances that are rarely covered and become difficult to analyze. This paper covers these transient operational issues evaluating them in time, frequency, and time-frequency domain.