The Research On Start Control System Of Aviation AC Starter/Generator

Starter/generator technologies, as key technologies for More Electric Aircraft(MEA), have attracted more and more attention. Three-stage brushless synchronous generators are currently the most widely used motors in Chinese aviation power field. There is great significance if the starter/generator technologies can be achieved on its original structure. However, Chinese current start control technology is not mature and practical enough to be applied on products and much research is still needed. Therefore, this dissertation is committed to the research of aviation three-stage brushless synchronous generators start control system. Several key issues in the practical start process are analyzed.Three-stage brushless synchronous motors are modeled in this dissertation. The mathematical models of the main generator and exciter are derived in detail using matrix theory. Coordinate transformation is described and the simulation models of the main generator and exciter are developed.According to the structure and applications characteristics of three-stage brushless synchronous motors, a method of estimating the initial rotor position of a three-stage brushless synchronous motor at standstill is presented. This method is not sensitive to motor parameters. Experimental results show that the estimated initial rotor position error is within 0.5° in electrical angle, which can meet the requirements of start control of threestage brushless synchronous motors.The start principle when the exciter using single-phase AC excitation and AC-DC excitation switching method are described briefly. Based on this, a start control strategy which can limit the stator current of the main generator is proposed and analyzed and the simulation model of the start control system is established. The simulation and experimental results demonstrate that the start control strategy can performs the start control when the load is an aviation engine. The speed range is 0rpm-4000 rpm, the start torque is larger than 70 Nm and the start time is less than 60 s in the start process. Meanwhile, start control strategy can limit the stator current of the main generator effectively. The stator current of the main generator is limited to a given value when the load torque is too large. And when the load torque return to the range of the load capacity, the start system can restart immediately.A large number of experiments show that the microcontroller program and FieldProgrammable Gate Array(FPGA) program designed in this dissertation is reliable and stable in the start control process. The PC monitoring and control system is practical, scalable and easy to use. Besides, the upgrading and maintenance of the PC monitoring and control system is convenient.The start control system of three-stage brushless synchronous motors is analyzed in-depth and the load curve of an aircraft engine is realized in this dissertation. It has reference meaning for the start control system for further research and optimization.