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Efficiency improvement and power loss breakdown for a Lundell-alternator/active-rectifier system in automotive applications

Abstract:

A control strategy for a conventional Lundell alternator and an active-rectifier using different modulation schemes was proposed in previous work. The modulation techniques examined indicated that the system could operate more efficiently than a passive rectifier over a certain speed and power range. This paper extends the modulation scheme analysis using a SVM scheme with six commutations per switching cycle, giving better electrical and overall efficiency. Furthermore, a power loss breakdown is performed for the active-rectifier with the assistance of experimental and simulation results of double pulse tests. Switching loss estimation curves are produced allowing the loss examination of the active-rectifier. Switching losses account only for a minor portion of the total rectifier losses in comparison to conduction losses. Finally, a higher dc-link voltage of 14.5 V was introduced using SVM scheme, giving better efficiency, in order to exploit further the rectifier loss distribution.