Reserach On Speed Estimation Strategy Of Servo Drive System With Low Resolution Sensor

Permanent magnet synchronous motor(PMSM)has gradually became the mainstream in the field of ac speed control system and servo drive,widely used in household appliances,new energy,aerospace and industrial manufacturing,due to the benefits of high efficiency and reliable operation and s impler control system,etc.In order to obtain the high precise rotor position information,photoelectric encoder or the rotary transformer are often adopted,but this may greatly increase s the system cost,however,sensorless technology can not completely be applied to servo or industrial fields.As a result,low resolution position sensor technology has became one of the heat topic of researches,owing to the benefits of low cost and good control performance.In the paper,the low resolution position sensor signals and different types and different installation ways of hall position sensors are analyzed,and speed and position estimation strategies are proposed based on interval time detection of hall sector by analyzing how to obtain continuous high-resolution position signals from discrete low-resolution Hall signals.For the problem of higher estimation error in speed change of the method based on average speed,a method enhanced based on average acceleration is proposed.Above all,a method with current feedback to improve the starting performance,which is based on initial velocity compensation is proposed.The effectiveness of the three proposed approaches are verified from simulations.On the basis of the three methods,the vector tracking position o bserver method is proposed to improve the dynamic performance of the machine.It consists of average speed calculation,a position error detector,based on the unit back electromotive force,and speed compensation with controller adjusting,to better compensate for estimation than the method based on interval time detection.The structure of the observer is designed and the anti-electromotive force is observed by the slide mode observer,so as to improve the estimation accuracy.The simulation model is established in Mtalab to verify the effectiveness of this method.Finally,the low-resolution position sensor permanent magnet synchronous motor control technology is verified on a 750 W servo motor platform.The experimental results show that the average accel eration method with initial velocity compensation is higher than the average velocity method and the average acceleration method,and it is proved that the estimation performance of the vector tracking position observer is better than the three methods.Th e experimental results also prove the correctness of the algorithm and the correctness of the theoretical analysis.