Research On Design Methods And Efficiency Optimization Of Doubly Salient Starter-generator For Helicopter On-board Generation System

This thesis summarizes the current research and technical status of helicopter power supply system and starter/generator system.The development and research status of doubly salient motor are also summarized showing that the doubly salient starter/generator system has important application values and widespread prospects in helicopter on-board generation system.According to the performance index of the doubly salient starter/generator system,this thesis introduces the operation principle of the starting operation mode and power operation mode.Design flow of a doubly salient starter/generator is analyzed.Then explain the main contradiction in starter/generator design.The effects of three key structure parameters of doubly salient machine,including air gap,rotor pole width and the turns of armature winding,on the starting performance and generation performance are studied.The size equations of doubly salient generator under two different generation mode are derived and the range of important coefficient in sizing equations are studied.The nonlinear variable network magnetic circuit model of doubly salient generator are introduced and analyzed as well as the modeling and solution method.A calculation case of a 9kW 12/8-pole brushless dc DSES/G is designed by using sizing equation and nonlinear variable network magnetic circuit model.The FEA analysis result shows the design is reasonable.The strand circulating currents in armature windings of low voltage high current doubly salient generator are researched.The generation mechanism of strand circulating current are studied and three optimized armature winding configurations are proposed.The results of refined 2-D FEA model shows that the optimized armature winding configuration can suppress the strand circulating currents effectively and lead to significant efficiency improvement.Finally,a starter controller and two doubly salient starter/generator are developed.The experimental platform is built based on the starter controller,prototypes and a brush DC starter/generator.The experimental results show that the doubly salient brushless DC starter/generator system has the advantages of simple structure and flexible control and can realize the starter operation and generation operation.The experimental results also verify the suppression effect of the proposed optimized armature winding configuration on circulating current.