Aircraft Generator Design and Analysis

David Gross


Aerospace electrical power demands have been growing due to an increased amount of electrical load onboard aircraft. This increased load has come about as electrical power sources for various aircraft subsystems, such as pumps, compressors and flight controls, replace mechanical power sources. The main source of electrical power for an aircraft is a generator. The nature of emerging power demands on an aircraft causes increased temperatures and complex/dynamic loads; many contemporary generators are not necessarily designed to repeatedly tolerate such phenomena. Due to the need for high amounts of reliable electrical power among current and future aircraft, aerospace generators should be designed for reliability, stability, power density, and long-term durability. The objective of this thesis project was to determine if generator sizing techniques could be calculated to a reasonable accuracy for preliminary machine design optimization and analysis. A conceptual sizing tool was created in MATLAB using equations, assumptions, and rule-of-thumb metrics in an attempt to accomplish this objective. The tool was found to successfully analyze trends for given machine parameters, and provide initial sizing estimates for preliminary machine design. The confidence in the tool is strongest for the 40 kVA generator example simulated, due to the availability of similar generators (of which many aspects are known) for laboratory testing. Uncertainty increases in branching out from the 40 kVA generator design point, such as for the conceptual 250 kVA generator example simulated. Future work in this project includes improving weight/efficiency calculations and geometrical configurations, adding transient/subtransient reactance and thermal calculations, and using program results for Finite Element Analysis and direct-quadrature axis simulation programs.