Research On Design And Control Of Switched Reluctance Motor With DC Excitation

Switched Reluctance Motor with DC Excitation(SRDC)is a double salient synchronous motor with stator excitation.which inherits the advantages of simple and reliable structure of the switched reluctance motor;uses vector control method of permanent magnet synchronous motor to obtain good static and dynamic characteristics,and reduce the cost and volume of the controller;and can also achieve wide speed regulation operation by adjusting the excitation.In the modern era when rare earth resources are increasingly depleted,this high-performance motor system without permanent magnets has good application prospects.However,the international research on SRDC motors has just begun,and many key issues need to be solved urgently:the systematic mathematical model of SRDC motors,mechanism of torque and torque ripple generation of the motor is urgently needed for in-depth study;the design method of SRDC motor is not complete,and the torque ripple of the existing SRDC motor is relatively large;there is no perfect control model of SRDC motor,nor corresponding control strategy,even suitable position sensorless control method.Therefore,the work done in this thesis mainly includes:With the help of basic electromagnetic theory,the analytical calculation model of SRDC motor is established,and the mechanism of SRDC motor torque generation is revealed.On this basis,using the dual-axis reaction theory,a vector control mathematical model of the SRDC motor is established.The study found that the d and q windings of the SRDC motor are not completely decoupled,but there is a third harmonic coupling inductance that varies with the rotor position angle.At the same time,the d and q axis inductances of the motor are not constant,and there are also 3rd harmonic components that vary with the rotor position angle,but the average values of the d and q axis inductances are equal.In order to improve the vector control performance of the SRDC motor,the general vector control model is improved.The method of vector control using constant parameters and voltage compensation based on the rotor position is proposed,and the dynamic voltage compensation decoupling control model of the SRDC motor is established.The torque formula of the SRDC motor is derived,which shows that the electromagnetic torque of the SRDC motor not only has the excitation torque component,but also has the third harmonic additional torque that varies with the rotor position angle.Two new stator magnetic pole structures are proposed.Type ? pole shoes can effectively reduce torque ripple,and Type ? pole shoes can be used to suppress torque ripple and also increase torque output.When the increment of the pole arc angle of the pole shoe within the range of 2.5°?3°,The use of I-type pole shoe magnetic poles reduces the torque ripple of the 5.5kW motor from about 80%to 38%.When the angle between the pole shoe and the pole body is 90°,and the pole arc angle increment of the pole shoe is 2°?3°,the use of type ? pole shoe magnetic poles greatly reduces the torque ripple of the motor.When the angle between the pole shoe and the pole body is greater than 120°,and the pole arc angle increment of the pole shoe is 1.5°?2°,the use of type ? pole shoe magnetic poles increase the torque output of the motor.Based on the electromagnetic field finite element analysis,the design method of SRDC motor is studied.The number of poles of the stator and rotor of the SRDC motor can be matched in many ways,but the best match is 12/8 pole and 6/4 pole.The best rotor pole arc angle of 12/8 pole SRDC motor is 17°,and the best stator pole arc angle is 15°?16°.The stator pole taper should be within 3°,and the rotor pole taper should not be too large,within the range of 0°?12°.When the AC and DC winding turns ratio of each pole is 1:1,the maximum output torque can be obtained.The number of AC and DC winding turns of each pole should be adjusted,synthetically taking into account the loss,torque output and torque ripple.Finally,comprehensively considering the various performance indicators of the motor,an experimental prototype was designed and the experimental test was completed.The experimental results verified the correctness of the design method.The vector control of the SRDC motor with minimum loss is studied,and the best match between the excitation and armature current is achieved through the minimum loss control strategy.Decoupling control is realize through dynamic voltage compensation.In order to improve the robustness and dynamic response characteristics of the control system,an H? speed controller based on sliding mode observer and an internal model current decoupling controller based on parameter identification are designed.Simlation and experimental results verify the effectiveness of this method..Research on the indirect position detection technology of SRDC motor is carried out,and a method of applying pulse injection method for accurate initial position detection is proposed;a method of using d and q axis inductance for operating position detection is proposed.The experimental results show that the indirect position detection method proposed in this thesis has high accuracy and can adapt to different speed requirements.