Realization Of Low-noise High-speed Sensorless Control Strategy Of Switched Reluctance Motors

Compared with traditional motors,switched reluctance motors have many advantages,but the presence of the position sensors weakens these advantages.Therefore,in recent years,the research on the sensorless control strategy of switched reluctance motors,especially the current-gradient method,has been widely concerned.However,the current-gradient method regards the current peak position as the position that the stator tooth and rotor tooth overlap,there is a large fixed error when estimating the position,and there is large vibration noise in the switched reluctance motor at the natural frequency.Aiming to solve the above-mentioned problems,the current-gradient method is improved,and a low-noise high-speed sensorless control strategy of switched reluctance motors is realized based on the improved method in this thesis.Firstly,the basic theory of switched reluctance motors and the current-gradient method is elaborated,and the main source of noise in switched reluctance motors is analyzed,which is the resonance due to coincidence of the frequency of current harmonics and the natural frequency.Secondly,several approaches are proposed,including:(1)Deduce the relationship between the current rising slope and the phase inductance,phase current,and rotor position,so as to derive the law that the current peak position varies as the turn-on angle,the DC bus voltage,and the angle speed,thus deriving the actual current peak position.(2)Set up a look-up table mapping from the turn-on angle,the DC bus voltage,and the angle speed to the current peak position deviation,so as to correct the current peak position,thus reducing the fixed error of the angle estimation.(3)Reserve the random error of the angle estimation,so as to destroy the periodicity of the phase current,thus reducing vibration noise at the natural frequency.Finally,the simulation model is established using MATLAB/Simulink,and the actual measurement platform is built using a 6/4 pole switched reluctance motor.Through the simulation and actual measurement,the control strategy is verified.As is demonstrated by the tested results,the control strategy implemented in this thesis lowers the angle error to less than 2 degrees within 20,000 rpm,reduces the vibration acceleration by 40.8% in the natural frequency,and decreases the noise by 6dB,which meets the design requirements.