Research On Switched Reluctance Motor Position Detection Technology Based On Full Cycle Inductance Method

Switched reluctance motor(SRM)has the characteristics of simple,flexible control and less energy consumption.At present,it has been widely used in textile machinery,traction transport machinery,aerospace and other fields.The motor steadily operates and high performance control depends on accurate rotor position information.At present,most position sensors are used to obtain rotor position information,which undoubtedly increases the complexity and cost of the system and also limits the operation in special environments such as vibration and dust.application.Therefore,this paper proposed a position sensorless control technology based on the full-period inductance method.This paper takes a three-phase 12/8-pole switched reluctance motor as the research object.In order to make the control more precise,the flux linkage data of its four special positions are measured according to the torque balance method.The nonlinear flux linkage curve familyψ(i,θ)and the nonlinear static torque curve family T(i,θ)are calculated through the mathematical analysis and the nonlinear model of SRM is established,which lays the foundation for the research of the entire non-position detection control system.The position sensorless control system adopts high-frequency pulse injection method when the motor starts,determines the initial position according to the response current of the winding,and determines the initial conduction phase.When the motor is running,the current slope difference is used to calculate the full-period inductance,and the rotor speed is calculated according to the time difference between the intersection point and the intersection point between the three-phase full-period inductance,and then the rotor position is estimated.However,in this method,when the magnetic circuit is saturated,the inductance intersection point of the high-inductance area will shift and leads to errors in position estimation.Two optimization strategies are proposed for this problem.The first is the inductance intersection compensation method in the high inductance area:when the motor is in the magnetic circuit saturation,the functional relationship between the saturation current and the offset angle is constructed,and the inductance intersection is corrected in real time according to the functional relationship proposed.The second is the non-conducting phase inductance threshold method:the inductance of the non-conducting phase is not affected by the saturation of the magnetic circuit,and the inductance threshold is set at a special position in the high inductance area,and the inductance threshold is combined with the pulse signal generated by the non-conducting phase inductance.As a pulse at a special location in the high inductance area.On the basis of the above theoretical analysis,perform simulation analysis on the improved control scheme through the simulation platform,It is verified that the improved strategies can effectively reduce the influence of magnetic circuit saturation on position estimation to varying degrees and the position estimation of the non-conducting phase inductance threshold method is relatively more accurate,the fault tolerance rate when the non-magnetic circuit is saturated is improved.Finally,a hardware experiment platform was built to identify the initial position of the rotor at startup.The experiment verified that the improved strategy is consistent with the simulation results,which can accurately estimate the rotor speed and position,and realize positionless operation under different speeds and load conditions.