42 V load dump transient and centralised active suppression

The aim of this paper is to characterise the load dump characteristics of a three-phase, 42 V, 6 kW alternator using SPICE modelling techniques. The specification calls for a maximum overvoltage of 58 V. The purpose of the limited voltage is to improve safety and also enable the use of lower voltage semiconductors thereby reducing cost. In order to be able to use a centralised active clamp, the load dump period has to be kept short to reduce as much as possible the energy to be dissipated. This is achieved by the design of the field winding excitation circuit