Model-based digital controller for a variable frequency synchronous generator with brushless exciter

This work describes the design and implementation of a DSP-based control regulating the output voltage of an electric generator for aircraft applications. Voltage regulation in an aircraft system is a challenging task due to a wide range of operating conditions. Control schemes based on the model of synchronous generators have been proposed because they naturally account for changes in the operation conditions. This paper proposes a multi-loop controller algorithm with model-based characteristics. That control algorithm was developed in simulations and tested experimentally in a DSP implementation. Simulation and test results show considerable improvement in the performance when compared to current practices. The controller has excitation and armature current loops whose characteristics are derived from the parameters of the machine and do not require additional tuning. Moreover, the model based characteristics produce a more uniform response in all the different operation conditions. In this way, the proposed controller algorithm overcomes some major issues currently existing for the type of applications under study.