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The electrical power demand in automobiles is rising steadily, especially in luxury vehicles, due to new electrical systems that enhance passenger comfort and safety. The present 14 V bus and Lundell based alternators are being pushed to their limits to meet these higher loads. The 42 V or higher voltage bus system in future automobiles enables a number of new features that require high power including electric compressors for HVAC. Electric compressors have advantages of low refrigerant emissions, flexible packaging and an efficient variable speed operation. These are intended mainly for “stop and go” vehicles with engine shuts-off during stops to improve fuel economy or for vehicles equipped with auxiliary power unit such as fuel cell. A cost effective semi-integrated position sensorless permanent magnet brushless motor has been designed, built and tested over the wide speed range with overall system efficiency of 85% over the significant portion of the operating range.

Introduction of higher DC system voltage distribution networks greater than 24V in future passenger vehicles appears to be an unavoidable consequence of meeting the increasing future electrical power demand. Higher voltage electrical distribution networks in vehicles force considerable component and system changes regarding electrical safety and reliability. In the event of an arc fault, e.g. when a wire is pinched or cut, or disengaged terminals under load etc., the resulting current may be significantly lower than the trip current of the protection devices such as fuses and circuit breakers. In these cases either the fault is cleared late (depending on the time/current characteristics of the fuse) or, in some cases fault may not clear, causing considerable damage and safety hazards. Two cost effective arc fault detection schemes were developed, built and tested with different loads including motor loads to clear both parallel and series arc faults in a 42 V DC network.