Research On Sensorless Control Of Switched Reluctance Motor

Switched Reluctance Motor(SRM)is a rare-earth-free motor.Due to its simple and solid structure,wide speed range,strong fault tolerance,and low environmental dependence,it has been widely used in the field of power transmission application.The existence of position sensors in the SRM drive system increases the cost and complexity of the system,and reduces the reliability of the system operation.Therefore,it is of great practical significance to carry out research on sensorless control algorithms for switched reluctance motor.In this paper,the issue of sensorless control of switched reluctance motors is studied from following aspects: initial positioning,medium and low speed operation,medium and high speed operation,and full speed operation,and related control algorithms are proposed respectively.In view of the initial positioning of the switched reluctance motor,a triangle-like algorithm based on a linear model of the peak value of the impulse current was proposed.The algorithm establishes a linear model by piecewise linearizing the full-cycle impulse response current peak curve obtained.Combined with the existing rotor partitioning strategy,a set of similar triangles containing peak pulse current and rotor position information is constructed,and the function relationship between the rotor position angle and the peak value of the three-phase impulse current is derived through similarity theory.The algorithm does not need any prior knowledge in the implementation process,the process is easy to implement and calculate.Through experimental verification,the algorithm has stronger operability and higher positioning accuracy than the two existing positioning algorithms.For low-speed operation of the switched reluctance motor,this paper proposes a seneorless algorithm for winding commutation control using the characteristic point detection of the phase current slope difference curve based on the theoretical study of the phase current slope difference.The algorithm fully considers the response characteristics of the current slope difference curve under different rotor positions and current amplitudes,and analyzes the distribution and offset of the characteristic points of the current slope difference curve when the SRM under single-phase and singlephase two-phase turns on operation.Corresponding feature point detection commutation schemes are provided for different control methods to improve the accuracy of commutation point detection.Aiming at the problem of sensorless control of switched reluctance motor at medium and high speed and full speed range,this paper proposes a strategy for control mode switching based on the comparison of the number of chopping operation in a single excitation cycle.This method ensures the continuity of the motor at full speed,meanwhile,the accuracy of the sensorless algorithm in the low and medium speed operation is considered.For sensorless operation at full speed,based on the analysis of the current waveforms at each speed,this paper comprehensively compares the constraints and performance of different current gradient algorithms to determine the algorithm selection in the high-speed phase of the motor.This algorithm is then combined with the low and medium speed sensorless algorithm and the control mode switching strategy to ultimately achieve positionless continuous operation at full speed...