Research On Electric Power Assist Operation Control Of Permanent Magnet Synchronous Motor Based On Hall Sensor

In recent years,with the national call for energy conservation and emission reduction and the strengthening of social awareness of environmental protection,people’s travel methods have gradually changed,and more and more people choose simpler travel methods.Among them,electric mopeds are an emerging electric power The vehicle can not only meet the requirements of longer distance riding,but also continue the light characteristics of bicycles.The power assist control system of electric bicycles uses discrete Hall sensors as the sensor for detecting the rotor position of the permanent magnet synchronous motor.In the actual operation process,Hall sensor failures occur more frequently,which will directly restrict the stability of the control system;in the power assist control system Among them,the assist torque control algorithm is the core strategy of the system.When the load of the electric assist vehicle changes or the road slope changes,how to calculate the assist torque becomes a difficult research point.In view of the above problems,this thesis studies the power assist control system of electric bicycles from the following aspects,as follows:Firstly,aiming at the fault problem of Hall sensor,a fault-tolerant control method of rotor position information based on the phase characteristics of Hall sensor signal is proposed.According to the phase characteristics of the output signal of the three-phase Hall position sensor,the fault detection of the original Hall position sensor is improved.The method improves the efficiency of fault detection;then according to the relationship between the three-phase Hall position signals,the transition delay relationship table of the reconstruction of the Hall signal when any phase Hall position sensor fails is given,and Based on the calculation formula of the time taken by the rotor to rotate through the corresponding electrical angle,based on the transition delay relationship table of the Hall signal reconstruction,a position information reconstruction for single-phase or two-phase Hall position sensor faults is proposed.The method is combined with the specific reconstruction methods of single-phase Hall fault and two-phase Hall fault.Secondly,this thesis proposes a torque control algorithm based on model reference adaptation based on the poor assisting effect of electric bicycles.According to the Lyapunov stability theory,the second Lyapunov method is used to derive the model reference adaptive control.The adaptive control rate of the system,the adaptive mechanism gradually changes the regulator parameters according to the adaptive control law,so that the output or state of the controlled object gradually tends to the output or state of the reference model,and finally obtains the desired adjustable system output.Finally,the mathematical model of the controlled object is established.By comparing with the simulation results of different assist torque control strategies,the effectiveness of the model-based adaptive control algorithm is verified under the conditions of load changes and slope changes.Finally,an experimental platform for electric mopeds is built.The hub-type permanent magnet synchronous motor is used as the control object,and STM32F030 is used as the main control chip.First,the improved Hall position sensor fault detection method and the rotor position information fault-tolerant control method are verified through the fault insertion experiment.After that,through the real vehicle road condition test,the actual riding effect of the adaptive torque control algorithm and the open-loop 1:1 control algorithm were compared.improve.