Patent 5397975 Issued on March 14, 1995. Estimated Expiration Date: June 14, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
A hybrid alternator includes a stator and a rotor, with the rotor having longitudinally separate wound field and permanent magnet rotor portions. A rotor excitation circuit applies a forward polarity to the wound field rotor portion to increase output in a boosting mode at low RPMs and a reverse polarity to decrease output at high RPMs in a bucking mode to maintain a constant voltage output. Alternative embodiments combine a magnetic flux concentrating design for efficient low speed operation with integral strength for high speed capability. Dual voltage output is provided either through dual stator windings or through a voltage converter circuit. Single voltage output is provided using only one stator winding.