Starting Control Strategy For An Aricraft Start Generator

Aircraft start generator is widely applied to the aero power-supply system due to its advantages of high reliability,low maintance and operation cost as well as easy implementation of starting and generation.When an aircraft start generator operates in the starting mode,the appropriate excitation structure of the main exciter and the control strategy of the main generator must be achieved in order to drive the aero engine from standstill to nominal speed steadily.Therefore,this paper focuses on the starting control technology and current ripple reduction method of the aircraft start generator in the starting mode.Firstly,the structure of the aircraft start generator is introduced.And the mathematical models of the main generator and the main exciter are built.Then the starting working principle is described in detail,and the optimal excitation and control strategy applied to the machine in the paper are selected based on the simulation and analysis.Secondly,the small-signal model for the aircraft start generator in the starting mode is created.Because the LC filter has significant influence on dynamic characteristics of the whole system,the transfer function is deduced to achieve the optimal control parameters of the current and speed controllers.Furthermore,the influence of dead-time effects in the two-level voltage source inverter on the current ripple in the main generator is analysed.Finally,simulation results show the validity of the described model and VSFPWM.Thirdly,the starting controller based on DSP and FPGA is constructed and the hardware circuits are introduced,including the design process of the main power circuit,the conditioning circuit and the digital circuit.Then the programming of DSP and FPGA is presented in the form of software flow charts.At last,the experiments of the LC filter,current ripple reduction and starting control are conducted based on the test platform in the laboratory,which prove the effectiveness and validity of the mentioned small-signal model and control strategy.