Development of variable-shaft-speed alternator
Abstract
A variable shaft speed alternator (VSSA) consists of an ordinary unmodified 1-1/2 Hp wound-rotor motor, with polyphase excitation controlled by solid state switching and a hybrid of analog and digital circuitry. This circuitry senses both shaft speed and line phase resulting in logic levels which control the current flow in each rotor coil. A first order polynomial was found using the least-squares regression method which accurately expressed the relationship among shaft speed, excitation power, and output power, VSSA torque was inferred from observations to be proportional to output power. Efficiency for converting mechanical power to electrical was inferred over a range of shaft speeds. A break-even speed below which no net power is produced was observed to be 0.375 of the synchronous speed for all output power levels. Similar behavior was observed with power fed to the power network (grid). Additional measurements involved VSSA performance at various power factors.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- February 1982
- Bibcode:
- 1982STIN...8327139R
- Keywords:
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- Ac Generators;
- Electric Generators;
- Shafts (Machine Elements);
- Velocity;
- Fourier Transformation;
- Phase Locked Systems;
- Regression Analysis;
- Electronics and Electrical Engineering