Research On Sensorless Control Strategy Of Synchronous Reluctance Motor

With the merits of simple structure,low cost,high-energy efficiency and wide speed adjustment,Synchronous Reluctance Motor（Syn RM）has been increasingly used in various fields such as industrial production and new energy vehicles,etc.The high-performance control of Syn RM needs to obtain accurate rotor position.However,the position sensor not only magnify costs and take up space,but also in harsh working environment,the sensor may lose accuracy or even failure,reducing the reliability of the system.To solve this problem,the sensorless control strategy of Syn RM is studied in this thesis.And its main work is as follows:Firstly,this thesis describes the basic structure and working principle of Syn RM,and its mathematical model in two-phase synchronous rotating coordinate system is deduced.Through the analysis of vector control and spatial vector pulse width modulation,the simulation model of the vector control system of Syn RM is constructed,which establishes the groundwork for the follow-up research.Secondly,the problem of dynamic coupling of current in the vector control system is analyzed.And the simulation experiment shows that the traditional feed-forward decoupling effect commonly used in engineering needs to rely on accurate parameters,while the inductance parameters of Syn RM has nonlinear characteristics due to its special structural.Aiming at sloving these problems,this section proposes an improved feed-forward decoupling control strategy based on the recursive least squares method with forgetting factor by substituting the inductance on-line identification value into the voltage feedforward decoupling control.Through simulation analysis,it shows the improved control strategy boosts the dynamic and static behaviour and the robustness of the system.Then,the open-loop and closed-loop sensorless control strategies are analyzed for different performance requirements.Among them,the closed-loop sensorless vector control is mainly studied.In the low-speed region,the pulse high frequency voltage injection method is used to design a reasonable scheme of extracting rotor position information and simplify the filtering process,meanwhile the simulation verifies that it has better performance in this speed region.In order to reduce the chattering and steady-state errors,the sliding mode observer method is used in the medium and high-speed region with the S-type saturation function instead of conformance function,and its availavility is demonstrated by simulation contrast experiment.In the transition speed area,a weighted composite control method is designed to ensure that the above two control algorithms can switch smoothly.The simulation results show that the composite control combines the advantages of the two methods,so that the full speed range of Syn RM sensorless vector control achieves good operation performance.Finally,an experimental platform for the Syn RM control system is built,and the soft hardware of this system is designed.After debugging,some relevant experiments are completed on the experimental platform,which verifies the effectiveness of these control methods and the rationality of the software and hardware design.