Design and Evaluation of a 42 V Automotive Alternator with Integrated Switched-Mode Rectifier

This paper presents techniques for the design of high-power Lundell alternators with integrated switched-mode rectifiers. A multi-section stator winding and interleaved rectifier arrangement is introduced that enables high power levels to be achieved using small semiconductor devices, and which greatly reduces the output filter capacitor requirements. We also demonstrate control methods suited to this interleaved system. In addition to accurate closed-loop output voltage control, we introduce methods to provide (partial) synchronous rectification for reduced loss, and to provide tight load dump transient control. The proposed technology is validated in the design and experimental evaluation of a 42 V, 3.4 kW alternator with fully integrated power electronics and controls. The prototype alternator achieves approximately a factor of 2.1 increase in power and 1.6 increase in power density as compared to a conventional diode-rectified alternator.