EMC in dual voltage vehicle electrical system: experimental investigation of transient disturbance problems and comparison with conventional 14 V electrical systems behaviour

This paper is focused on some electromagnetic compatibility problems concerning automotive electrical loads in dual-voltage vehicle architecture. Transient disturbances produced by a new prototypical vehicle electrical load have been analysed. In particular the considered electrical load is a DC cooling fan drive intended for a 42 V rated voltage. Both current and voltage transient disturbances produced by the 42 V cooling fan drive have been measured and critically analysed, in time and frequency domain. The reason for such an investigation is to define the characteristics of electromagnetic environment in new dual-voltage (14/42 V) vehicle electrical architecture and so to contribute to technical standardisation of the automobiles in the field of EMC. Suitable experimental measurement systems have been set up in order to measure and experimentally compare transient disturbances produced by the considered 42 V drive and 14 V cooling fan drive (used in conventional vehicle electrical architecture), both during start and stop operation. Particular care has been put in realising the experimental measurement system for 42 V drive, as no related technical standard references currently exist. Moreover the effects due to the introduction of a power electronic device, instead of a conventional electromechanical relay, have been evaluated, showing a reduction of transients´ heaviness.