Research On Control Strategy Of High-power Switched Reluctance Starter/Generator System

In order to improve aircraft energy efficiency,reduce maintenance costs,and reduce emissions,the concept of multi-electric/all-electric aircraft came into being.As one of the key technologies of multi-electric aircraft,starter/generator technology can reduce the volume and weight of the power supply system and increase the power density of the system.Switched reluctance motor has the characteristics of simple structure,low cost,high reliability,adaptability to harsh working conditions such as high speed and high temperature,and flexible switching between electric and power generation status,making it particularly suitable for aviation high-voltage starter/generator systems.In recent years,switched reluctance motor has received extensive attention and research.With the further development of multi-electric aircraft,the demand for onboard power continues to increase.At present,the application of the domestic switched reluctance starter/generator system is still in the low-power stage,so researches on the key technologies of the switched reluctance starter/generator system have very urgent application requirements and practical significance.First,this article briefly discusses the research status of several aviation starter/generator systems and explains the research background of the switched reluctance starter/generator system.Combining with the challenges faced by high-power switched reluctance starter/generator systems and the current research status of control strategies,the research contents of this article are introduced.Next,according to the performance requirements of the starter/generator system,a dualchannel 12/8-pole switched reluctance motor and its power converter structure are designed.Combining the characteristics of inductance and the mathematical model of the motor,the operation principle of SRM is explained,the nonlinear simulation model of SRM is built,and the basic control strategy is analyzed.Then,based on the switched reluctance motor nonlinear model,the starter/generator control strategies are simulated,analyzed and verified.Under the electric state,aiming at torque ripple problem,the advantages and disadvantages of the traditional direct instantaneous torque control are analyzed emphatically.The direct instantaneous torque control algorithm is optimized and improved by sector subdivision,and a new type of direct instantaneous torque control based on the different phases and sectors using pulse width modulation is proposed.Through simulation and comparison analysis,the ability of the new type of direct instantaneous torque control to suppress torque ripple under limited switching frequency is verified.In the power generation state,there is a problem of uncontrollable high-speed generation current.The voltage and current double closed-loop structure are optimized.Through real-time monitoring of load power changes,according to the current motor speed and load power,the switch table obtained in advance is queried to get the most optimal switching angle to ensure the stability of the generated voltage when the load changes at different speeds.In addition,aiming at the angle delay problem caused by the control cycle in the whole starting/generating state,the basis for the judgment of angle compensation is given,and the relationship between the angle compensation amount and the speed and control cycle is theoretically deduced,and two types are proposed.The simulation comparison of the power generation waveform before and after compensation shows that the power generation control after angle compensation is more accurate at low switching frequency and the voltage fluctuation is smaller,which verifies the necessity of angle compensation.Finally,adopt the dual DSP and CPLD architecture to design the controller software and hardware,apply code generation technology to complete the software program development.Conduct high-power electric and power generation experiments on the 12/8-pole switched reluctance starter/generator experimental platform,experiment results meet the system performance requirements,and verify the correctness of the angle compensation.