Study On Sliding Mode Observer For Sensorless Control Of The Permanent-magnet Synchronous Motor

With the rapid development of the national economy,cars have become an indispensable part of people's life,which greatly facilitates people'stravel.However,vehicle needs a lot of fuel consumption,which is accompanied by environmental pollution and energy exhaustion.New energy vehicles have been widely paid attention to.As an indispensable part of new energy vehicles,electric vehicles are also concerned by the users.The permanent-magnet synchronous motor(PMSM)used in the new energy vehicle has the advantages of small volume,high efficiency and high power density,and it has been widely used in new energy vehicles.Traditional PMSM is equipped with mechanical sensors on rotor shaft to detect motor speed and position angle.However,the installation of mechanical sensors will inevitably lead to the increase of the size of the motor and the loss of the motor performance.In addition,the reliability of the motor in the bad environment will be reduced.Therefore,sensorless control has entered the line of vision.Based on vector control theory of PMSM,this paper eliminates mechanical sensors and adopts two control methods to study sensorless control of motor.Firstly,the sensorless control based on model reference adaptive control is investigated.It can be concluded from the research results that this method can effectively identify the speed and position angle of motor without mechanical sensors.However,this method has a strong dependence on the parameters of the motor.When the working environment of the motor changes,especially when the environment temperature changes,the resistance and inductance of the motor will be also changed.At this time,the model reference adaptive method is not ideal if the parameters of the motor can not be fed back in real time.Moreover,if the speed mutation,the motor needs long time to restabilize.Then,the sensorless control based on sliding mode observer is investigated.It can be concluded from the research results that this method can accurately estimate the speed and position angle of the motor.The traditional sliding mode observer can produce serious jitter when estimating the speed and position angle of the motor.On this basis,the modified sliding mode observer is further improved.The modified sliding mode observer can greatly weaken the jitter phenomenon and have strong anti-interference ability.After the speed mutation,the time of the motor's restabilization needs is very short.In order to verify the validity and feasibility of the two methods,the MATLAB/Simlink simulation analysis is used to control the PMSM with sensorless control.The experimental verification is carried out on the Dspace platform.The experimental results show that the two control methods can estimate the speed and position angle of the motor,and the model reference adaptive control method is a little worse than the sliding mode observer method.