A New Racing Engine Charging System with a Permanent Magnet Alternator

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.