Dual voltage alternator

With an ever increasing amount of installed electrical load in modern automobiles there is a corresponding increase in the demands placed on the automotive electrical system. This system's inability to supply these demands efficiently at 12 V suggests that a new higher system voltage will soon become necessary. Unfortunately re-engineering, re-design and parts procurement costs prohibit a single change to a higher system voltage. A dual voltage architecture provides a simple, yet effective, solution to this problem. High demand loads such as electrically heated catalysts, heated windshields and other various heater loads can be supplied efficiently at a voltage much higher than 12 V while the traditional 12 V standard is retained to supply filament lighting, semiconductors and other loads which cannot make a transition to a higher system voltage without prohibitive consequences. The nominal output voltage of a conventional passenger car alternator is limited to 12-14 V over the entire speed range despite the fact that this voltage is initially reached at a relatively low speed. This paper describes the development of a new design of automotive alternator which allows the DC output voltage to rise to 32 V which is more suited to efficient supply of heater loads. This utilises more of the alternators output capability while retaining the traditional 12 V standard for the many other loads not suitable for higher voltage operation. Such an alternator was designed to generate and regulate two independent DC voltages within a single housing without compromising the existing 12 V system.