| Switched reluctance motors are widely used in harsh working occasions due to their advantages of simple structure,low cost and strong fault-tolerance ability.The detection link is a weak link of the switched reluctance motor system,which mainly includes current sensors and position sensors.Under severe working conditions,they are extremely susceptible to the influence of damp,dusty,electromagnetic and other interference environments and then reduces the reliability of the system.Consequently,this paper improves the reliability of the switched reluctance motor system through the optimization of the detection link.In terms of reliability evaluation,this paper presents the modeling process and solution methods of the fault tree model and Markov model,which lays the foundation for the reliability evaluation of the optimization methods of the detection link.In addition,this paper also quantitatively evaluates the static and dynamic reliability of the system under the traditional phase current detection method,which provides a reference for the reliability improvement effect of the optimization of the detection link.In terms of current detection,this paper presents a phase current reconstruction method based on two current sensors,which divides a rotor cycle into 8 intervals,and uses a decoupling strategy to achieve phase current reconstruction in each interval.This method reduces the number of current sensors and reduces the cost and volume of the system.In addition,this article also quantitatively analyzes the static and dynamic reliability of the system under the phase current reconstruction method.By comparing with the reliability results of the traditional phase current detection method,it shows that the optimization of the current detection link improves the static reliability of the system,but reduces the dynamic reliability of the system.In terms of position detection,this paper presents a position sensorless control method based on pulse injection,which estimates the rotor alignment position by injecting detection pulses in the demagnetization and idle intervals.This method overcomes the shortcomings of the traditional pulse injection method with negative torque generation,get rid of the dependence of the switched reluctance motor system on the position sensor,and reduce the cost and volume of the system.In addition,this paper also quantitatively analyzes the static and dynamic reliability of the system under the position sensorless control method.By comparing with the reliability results of the traditional phase current detection method,it shows that the optimization of the position detection link improves the static and dynamic reliability of the system.There are 58 figures,12 tables and 84 references in this thesis. |
