Transient voltage characterization for automotive 42 volt power systems

The rapid escalation of electrical content in current and future automotive applications has necessitated the need for significant increases in electrical power. To meet this demand, automotive manufacturers are developing 42 volt power distribution systems. 42 volts will better meet the power requirements of these, new features and also permit the electrification of ancillaries up to approximately 10 kW which the present 14 volt power systems cannot practically and economically provide. However, the introduction of higher voltage power systems creates new challenges in regards to circuit protection from voltage transients produced from switched loads. This paper focuses on the transients produced by switching inductive loads on 14 and 42 volt systems. A complete analysis is performed on 14 and 42 volt door lock motors for three different types of switches. Measurements were also made on 14 and 42 volt window motors and air conditioning clutch coils. All measurements are compared to simulated results. This work builds on previous studies of prediction of switch arcing. The results of this study are used to develop new conducted immunity standards for automotive products.