Foil field lundell alternator with rotating power electronics

The power requirements of automotive alternators are increasing significantly due to the introduction of new vehicle electrical loads. We aim to improve alternator power density with the use of a foil field winding in the Lundell or claw-pole alternator. Foil field windings are shown to provide higher conductor packing factors than conventional wire wound fields (e.g. 73% as opposed to 64% for a typical wire wound design) and offer improved thermal transfer properties. These advantages are demonstrated to enable significant increases in field ampere turns and achievable alternator output power. However, realizing these advantages requires a new field excitation circuit that can deliver high field current at a low voltage, without exceeding the limited current ratings of alternator brushes.