The Research Of Rotor Position Estimation Method Of Wound-rotor Synchronous Starter/Generator

Wound-rotor synchronous starter/generator(WSSG)is widely used as generator in aircraft AC power system nowadays.If the WSSG can be used as a motor to start aero-engine,a specialized starter can be left out.However,at starting stage,WSSG needs a rotary transformer to obtain main machine(MM)’s rotor position.If the rotor position of MM can be estimated in real time,the rotary transformer can be removed.The remove of rotary transformer can improve starting system’s reliability and reduce starting system’s complexity,volume,weight and costs,which has great significance for the development of more/all-electric aircrafts.This paper mainly researches the key technology of WSSG’s rotor position estimation in real time.Firstly,this paper introduces the working principles of three kinds of saliency tracking rotor position estimation methods.Theoretical analysis of rotating high frequency voltage injection rotor position estimation method when MM’s d-axis inductance varies a lot is done,simulation is done next.These three kinds of rotor position estimation methods are summarized,and the conclusion shows that these saliency tracking rotor position estimation methods are not suitable for WSSG’s rotor position estimation.Secondly,to overcome the shortcomings of saliency tracking method,on the basis of the National Natural Science Foundation of China(the name is “Rotor position estimation of wound-rotor synchronous starter/generator under the circumstance of saliency varying”)in tutor’s project team and project team’s early research idea,this paper proposes a novel MM’s rotor position estimation method,which injects a rotating voltage into MM’s stator and detects main exciter(ME)’s stator currents to estimate MM’s rotor position.The working principle of high frequency signal’s transmission in MM is analyzed,and the induced high frequency voltage in MM’s rotor winding is derived.The working principles of high frequency signal’s reverse direction transmission in rotating diode rectifier under three different kinds of commutation conditions are analyzed,and the current response in ME’s rotor is derived.Simulations of the first and second commutation conditions are done.Next,this paper analyzes the working principle of high frequency signal’s transmission in ME,derives the induced current in ME’s two-phase stator winding and introduces the signal processing procedures of ME’s stator current.Simulation and experiment of the proposed rotor position estimation method are done.Simulation and experiment results show that this method can realize low speed stage(below 200rpm)’s rotor position estimation,and the estimation accuracy is high enough for WSSG’s startup.Finally,this paper analyzes the rotor position estimation method which is based on MM’s back electromotive force(EMF).Based on the mathematical model of MM in dq coordinates,the working principle of the back EMF method is introduced in detail.The formulas are derived,and the signal processing procedures are introduced.Simulation and experiment of this method are done,simulation and experiment results show that this method can realize high speed stage’s rotor position estimation,and the estimation accuracy is high enough for WSSG’s startup.