Two-stage electric generator system

A two-stage electric generator system for converting mechanical energy from a wind or hydraulic driven turbine into electrical energy comprising, in combination:

• housing means;
• an exciter generator and a main generator in said housing means;
• a shaft rotatable in said housing means;
• said exciter generator consisting of permanent magnet means mounted to said housing means and of a rotor rotatably supported on said shaft, said rotor being made of non-magnetic material to eliminate cogging and static torque associated with permanent magnet excitation, said rotor including a one-phase winding distributed around the circumference thereof;
• said main generator consisting of a three-phase stator winding on a magnetic core mounted to said housing means and of a pole-type rotor rotatably supported on said shaft and having a winding wound on a magnetic core;
• a rectifying bridge rotatably mounted to said shaft;
• first means electrically connecting said one-phase winding to said rectifying bridge;
• second means electrically connecting said rectifying bridge to said winding of said main generator rotor whereby rotation of said shaft as a result of mechanical energy applied thereon generates a three-phase electric energy output from said stator winding, the normalized power versus speed curve of the generator intercepting the power versus speed curve of the turbine to assure a stable operating point around design speed;
• and
• means outside said housing and connected to said permanent magnet means to move said permanent magnet means away from said rotor of said exciter generator.

A two-stage electric generator system for converting mechanical energy from a wind or hydraulic driven turbine into electrical energy comprising, in combination:

• housing means;
• an exciter generator and a main generator in said housing means;
• a shaft rotatable in said housing means;
• said exciter generator consisting of permanent magnet means mounted to said housing means and of a rotor rotatably supported on said shaft, said rotor being made of non-magnetic material to eliminate cogging and static torque associated with permanent magnet excitation, said rotor including a one-phase winding distributed around the circumference thereof;
• said main generator consisting of a three-phase stator winding on a magnetic core mounted to said housing means and of a pole-type rotor rotatably supported on said shaft and having a winding wound on a magnetic core;
• a rectifying bridge rotatably mounted to said shaft;
• first means electrically connecting said one-phase winding to said rectifying bridge;
• and
• second means electrically connecting said rectifying bridge to said winding of said main generator rotor whereby rotation of said shaft as a result of mechanical energy applied thereon generates a three-phase electric energy output from said stator winding, the normalized power versus speed curve of the generator intercepting the power versus speed curve of the turbine to assure a stable operating point around design speed;
• and
• magnetic shunt means movable between said permanent magnet means and said rotor winding of said exceiter generator for weakening the flux of said permanent magnet means with respect to said exciter generator rotor.