Research On Position And Speed Sensorless Control Of Ipmsm At Full Speed Range

Permanent magnet synchronous motor(PMSM)is extensively utilized in many industrial fields because of its attractive characteristics such as high efficiency and compact design.The vector control method based on rotor flux orientation is the most commonly implemented approach and has a good control feature at the full-speed range.And the control feature relays on the high-precision speed encoder.However,the high-precision speed encoder equipment will increase the cost and volume of the system.In industrial applications requiring high power density and low cost,the sensorless control methods without position and speed sensors are used to estimate accurate speed information.Therefore,it is greatly significant to study the sensorless control method of interior permanent magnet synchronous motor in the full-speed range.To reflect physical processes occurring in a real machine with maximum accuracy.Firstly,this paper deals with mathematical modelling of the threephase IPMSM in different coordinate systems,improving variable speed and load torque capabilities.The corresponding vector control of IPMSM using a two-level voltage source inverter is established and tested.To overcome the drawbacks of vector control and solve the medium and high speed concerns,this paper presents the basic principle of MRAS,designs the reliable reference model and adjustable model.Then,a suitable adaptive law is derived using Popov’s superstability theorem.The simulation results demonstrated the effectiveness and correctness of MRAS at medium and high speeds.However,the position and speed estimation accuracy decrease at standstill and low-speed ranges.To solve the difficulties of MRAS to accurately estimate the rotor position and speed at low-speed regions,this paper deals with the design and modelling of HF injection.The appropriate HF signal parameters are designed,the adjustment and selection of filter settings are derived.A suitable extraction algorithm using the heterodyne approach for extracting angular rotor parameters is applied.The simulation results established the validity and accuracy of HFI at zero and low-speed range,but the HFI estimation accuracy of speed and position decreases at medium-high speeds.To establish the IPMSM speed sensorless control in the full speed range,this paper proposes a new weight factor allocation method based on the sigmoid function to realize the smooth switching between the two sensorless methods.In the low-speed range,the weight factor of the speed estimation value obtained by the sensorless method based on high-frequency injection is higher.In the high-speed range,the weight factor of the speed estimation obtained by the sensorless method based on model reference adaptation is higher.However,in the transition region,facing the problem of the accumulation of position errors from the two sensorless approaches at a constant speed might lead the estimation accuracy to decline.Therefore the switching interval or transition region may differ and vary.Thus,to guarantee the effectiveness of the proposed method,it is also necessary to set the speed of the switching interval reasonably.To solve this issue,the selection of switching speed intervals is based on the rotor position error of HFI.Finally,the simulation results verify the effectiveness and correctness of the proposed position and speed sensorless method at full speed range.Figures 33,Tables 3,References 83.