Inverterless high-power interior permanent-magnet automotive alternator

This paper describes a high-power brushless interior permanent-magnet (PM) automotive alternator which does not use an inverter. The "inverterless" alternator is designed with a high back electromotive force voltage and high reactance, and acts as a constant current source over much of its wide constant power operating speed range. In this configuration, a switched-mode rectifier can be used to regulate the dc output voltage and current, which avoids the complexity and high cost of an inverter. An analysis of the modeling and performance of interior PM machines in this inverterless topology is described. Experimental results showing an outstanding constant power speed range are presented for a 6-kW concept demonstrator machine tested using a three-phase resistive load to simulate inverterless operation.