Search Results

The market growth for electric-hybrid passenger vehicles has been very significant and is expected to reach nearly 25% of all vehicles sold in the US by 2015. Hybrid commercial vehicles are also being developed by several OEM's. This paper discusses the progress of Delphi Thermal Systems in developing an integrated electric compressor drive with high cooling capacity (9 kW+), sufficient for large hybrid SUV's and commercial vehicles such as Class 8 tractors with sleeper. An important driver for use of the electric compressor in the hybrid truck application is the reduction of engine idling time while maintaining comfort in the cab or sleeper. Design details of a compact 5 kW SPM motor, its inverter drive, and issues related to its integration into the compressor housing are described. Test results are given confirming excellent performance.

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.

A 3.4 kW, 42 V permanent magnet alternator based high power generation system was built and tested in the Delphi R&D laboratory. It is belt driven system with 3.37: 1 pulley ratio. The size of the alternator is slightly less than the production CS-144 Lundell machine with 1/3 less inertia. For cost reasons, the controller uses a single SCR bridge rectifier. The prototype, which is capable of producing 34A/80A at idle/cruising speed, has been tested in the laboratory yielding 84.5%/70.7% efficiencies. Up to cruising speed, the system shows an improvement in full load efficiencies of 5-6 percentile points over a similar 14 V permanent magnet machine with dual SCR bridge. This efficiency improvement is due to the reduction in the converter losses as the current is reduced to one third of its 14 V values even with the same copper losses in both machines.

An efficient light weight 425 Watts charging system was developed and built to meet the requirements of a 12-cylinder engine for racing application. The new system consists of a permanent magnet (PM) alternator with MAGNEQUENCH (MQ3) magnets and a high frequency switching regulator to regulate the output voltage over the engine speed range of 2,000-12,000 rpm. The system has been tested for 75% overall efficiency as compared to 38% for the present system over most of the speed range. Excellent dynamic response (less than 1 ms) has been measured, which allows the alternator to support pulsed loads, even if the battery is disconnected during operation. The new system weighs 3.73 kg vs 5.4 kg of the existing system.