Patent ID: 6081084
Filing Date: 2000-06-27
Classification: H02J,H02P,Y02T

Abstract:
An alternator driven by an engine, the alternator comprising:a. three phase stator windings having three stator winding outputs;b. a rotor having a rotor field winding magnetically coupled to said stator windings and driven by the engine to generate a back EMF in said stator windings and electrical current at said three stator winding outputs;c. a rectifier bridge having a dc output comprising a plurality of transistor switches, said plurality transistor switches comprising at least three pairs of connected upper transistor switches and lower transistor switches and each of said plurality of transistor switches including body diodes bridging said transistor switches, wherein each of said three stator winding outputs are electrically connected to said rectifier bridge between a respective pair of said upper transistor switches and said lower transistor switches;d. a zero crossing detector connected to said three stator winding outputs, said zero crossing detector operable to determine the zero voltage crossings across at least one of said body diodes of said transistor switches and generate a signal indicative of said zero voltage crossings, wherein said zero voltage crossings across at least one of said body diodes are representative of zero crossings of said back EMF in said stator windings;e. a microcontroller connected to said zero crossing detector, said microcontroller for receiving said signal indicative of said zero voltage crossings from said zero crossing detector and controlling the operation of said transistor switches in said rectifier bridge to control the phase angle of phase voltages at said three stator winding outputs and introduce a phase shift between said phase voltages and said back EMF.