An analysis and discussion of the voltage and current spectrum of claw-pole alternators for fault detection purposes

The `claw-pole´ type synchronous alternator is the heart of virtually all automotive Electric Power Generation and Storage (EPGS) system. Timely and accurate detection of alternator faults will not only decrease “walk-home” incidences for drivers but will also significantly decrease misdiagnoses, thereby resulting in significant warranty cost savings for auto manufacturers. This paper performs a general analysis on the voltage and current spectrum of the claw-pole alternators. Various harmonic components in the spectrum are explained from the first principles. The effect of the built-in rectifier on alternator voltage and current spectrum is also investigated. The analysis leads to a better understanding of claw-pole alternators especially for fault detection purposes.