This disclosure relates generally to power generation, and more specifically to a direct current (DC) synchronous machine.
Synchronous machines are known. Synchronous machines include a stationary portion and a rotating portion, where the rotating portion and the stationary portion each have at least one winding.
One application of synchronous machines is a starter/generator application for a gas turbine engine. Synchronous starter/generators are configured to function as a motor to first start the gas turbine engine. Once the engine is running, the synchronous starter/generator system can operate as a generator.
Some synchronous machines utilize a rotating DC field winding and a three-phase stator armature winding. When operating as a motor, the synchronous machine is coupled to an alternative current (AC) power source in order to supply motive power to a device with moving parts, such as the starter function or a pump or compressor. When operating as a generator, the synchronous machine is configured to supply AC current to one or more loads such as avionics equipment or motor driven loads on an aircraft. When DC output is required, the output voltage from the synchronous machine is rectified at the three-phase stator armature winding to produce direct current. There are challenges associated with current harmonics that adversely affect the generator efficiency, large volumetric and power density, and thermal losses on such rectifiers.