| Summary: | 碩士 === 國立中興大學 === 電機工程學系 === 88 === This thesis aims to develop a DC starter/generator control unit (SGCU) by using variable structure control (VSC) method. An engine is engaged with the starter/generator, which either draws electric power from the battery or converts mechanical power into electric power feeding to the loads. As the engine speed increases from zero, the starter/generator operation translates from starter, field weakening, off-line, and generator modes. In starter mode, a high starting torque is required to overcome the inertial loads of the mechanical components. As the rotating speed goes up, a field weakening procedure is conducted to maintain a positive accelerating torque. When the engine approaches the idle speed, the starter is about to go off-line and switches its role to that of a generator.
Field control is key to the SGCU design problem. Two primary issues in the field control problems — field weakening and voltage regulation, are elaborated in this thesis. In field weakening mode, the system is converted into a second-order current control problem; while in the generator mode, the system is a first-order voltage control problem. The system dynamics are linear, time varying, and with exogenous disturbances from loadings, engine speed, and field excitation voltage variations.
A VSC method is employed to account for these disturbances. The system is implemented on two PC-based control platforms using a high-level language (Microsoft C) and a man-machine-language (LabVIEW), respectively.
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