Design of high speed wound field synchronous generators

Abstract

Wound field synchronous generator has a long history for being implemented as power generation methods in power plants, standby power generation at 50 or 60 Hz. Recent demands for transportation electrification for automotive, marine and aerospace industry raise new requirements for power generation and traction applications. These new requirements includes high speed operation, increased power density and minimizing the cost. High speed and low weight requirements for a wound field synchronous generators result in a complex multi-physics analysis and iteration process. Nevertheless, no commercial tool is available to design a wound field synchronous generator from scratch with simple generator performance inputs and perform thermal and mechanical analysis. However, a parametrised multi-physics design tool for wound field synchronous generator should offer features as follows. First, individual physical field packaged modules for sizing and analysing a generator. Second, individual modules accepts identical generator data array as its inputs. Third, individual physical field analysing module can be upgraded within the modules without interfering other modules. Forth, additional modules can be easily integrated with the existing tools. In this thesis, a commercially unavailable multi-physics objected oriented design tool dedicated for high speed wound field synchronous generators is developed for designing a wound field synchronous generator from scratch with simple design inputs such as power, speed, terminal voltage and the speed offering features listed above. The objected oriented design tool for a wound field synchronous generatoriii is able to design a generator via an analytical sizing script, analysing its thermal and mechanical performance. A feasible high speed wound field synchronous generator design option is finalized through multiple iteration processes using the objected oriented design tool proposed in this thesis. This objected oriented wound field synchronous generator design tool also offers features of individual optimization and upgrades of existing design modules integrated in the tool. In addition, since objected oriented architectures are adopted for this tool, other design or analysing modules related to wound field synchronous generator such as rotor dynamics, bearing life time, insulation type and thickness, etc. are able to be integrated with existing tool without interfering with existing modules. In this thesis, M235-35A core is used to investigate the feasibility of low cost high speed wound field synchronous generators. Therefore, novel dovetails under each rotor pole are proposed to reduce the stress level so that a rotor core made of M235- 35A is able to survive the high speed operation. Open slot configuration for damper cages are also proposed in this thesis to address the high stress concentrated at the surface of rotor pole. Integrated damper cages are proposed to resolve the complex copper damper cage assembly process and the stress concentration at rotor pole surface at the same time.

Date of Award	30 Jul 2021
Original language	English
Awarding Institution	Univerisity of Nottingham
Supervisor	Michael Galea (Supervisor), He Zhang (Supervisor), Michele Degano (Supervisor), Gaurang Vakil (Supervisor) & Christopher Gerada (Supervisor)