Design Of The Low Cost PMSM Servo Controller Based On Parameter Identification

With the increasingly application of the vector control in servo drivers for permanent magnet synchronous motor,the servo system has developed to achieve the requirement of high precision and satisfactory performance.Parameter identification is a current research hotpot in many study fields of the servo drivers.However,for the low cost application of servo systems,the lowprecision sensors may cause high noises and errors of the current and position feedback,which brings adverse effect to the performance of servo motors and the precision of parameter identification as well.This paper has studied to obtain the motor parameters through parameter identification method,and the parameters of the controllers have been designed and adjusted based on the identification results,thus to improve the performance of low-cost servo divers.Firstly,the effect on voltage vector trajectory bringing by non-ideal factors of the inverter,as well as the effect on current,angle and speed feedback caused by the sensor errors have been analyzed in detail,followed by the quantitative derivation of the identification errors bringing by the factors described above.The equivalent voltages of resistance and inverter are identified offline by using the multi-amplitude voltage positioning method,thus the precision of the off-line identification for inductance can be improved by voltage compensation.The online step identification method has been proposed to avoid the degenerate-rank problem in the process of the resistance and flux linkage identification,as well as the mutual effect of identification results.Meanwhile,in view of the issue that the online identification results of inductance are mainly effected by the operating condition and the angle errors,this paper has proposed a high frequency injection algorithm with consideration of disturbance,which enhanced the precision and stability of the inductance identification.Finally,to identify the mechanical parameters of servo motors,an integral strategy for the inertia identification based on the fitting of friction torque has been proposed to decrease the identification errors caused by the speed noise and friction torque.This paper has designed parameters of the current and speed controller with the bandwidth of the servo system as the index.Followed by a state observer to optimize the speed feedback,which improved the stability and dynamic performance of the system.Finally,the observed load torque was utilized as the feedforward compensation for the current to suppress the speed fluctuation as results of torque mutation.Simulations and experiments have been carried out to verify the effectiveness and feasibility of the proposed parameter identification method and controller design of servo motors with the 94 W low-cost permanent magnet synchronous servo system as its research object.The results demonstrate that the proposed strategy can certainly improve the precision of the parameter identification method as well as the performance of the servo system.