Optimal Controller Design for More-Electric Aircraft Power Systems

Electrical energy is becoming more and more popular these days. Because energy efficiency has always been an important aspect for human kind, the vehicles which use energy efficiently are more preferable. The rapid changes in the technology allow us to build more electric systems such as more electric aircraft (MEA). The MEA concept is a major trend in today’s world, but building those vehicles faces some challenges. The subsystems of MEA which consume electricity rather than other energy sources might increase electrical loads of power electronic converters and motor drive systems. Motor drive systems and power electronic systems generally have characteristics of constant power loads (CPL). In small-signal analysis, CPL presents negative impedance that might deteriorate the power system stability margin. This thesis aims to model a typical MEA power system and design an optimal controller which is able to solve the stability issue with CPL. The dynamic model is derived using the equivalent circuit model and linearization around an operating point. This optimal control method provides a solution, which is optimal with respect to a quadratic performance index. MATLAB is used to solve algebraic Riccati equation and obtain figures for the simulation. When it is compared to the effect of conventional power system stabilizers (PSS), the proposed Linear Quadratic Regulator (LQR) gives more robust results. Moreover, the state feedback gain is calculated only for one operating point, but it works over wide range of operating conditions