Study On Online Parameter Estimation Of Permanent Magnet Synchronous Motor

Besides being able to monitor the possible faults,acquiring the Parameters of PMSM of a vector control system is also a way to improve the performance of the hold system.In a PMSM's vector control system,the current regulator's PI paremater could be well determined with the accurate parameter of the motor and the coupling term could be calculated with d-q axis inductance and rotor permanent flux linkage to improve the decoupling performance.Also the output torque could be calculated precisely according to the motor's real parameter to fullfill torque control.Appling system identification theory to PMSM's vector control system,achieving online parameter identification to the motor which realizes an accurate acquisition of the motor's real-time paramter is certainly necessary to be well researched.The main contents of this paper aiming online parameter identification are listed as follows:1)The model of PMSM in two-phase sychronous rotating coodinate is derived to prove the rank of PMSM's d-q axis model is less than the quantity of its parameters.Tendency of the change of motor parameters under different conditions is analysed and those methods to acquiring PMSM's paremeters by off-line tests are well researched especially the mesaurement of d-q axis inductance after considering the saturation of magnetic circuits.2)The voltage source invertor's non-ideal factors are considered including the on-off delay of power electronic device,the forward voltage drop while turning-on and the artificial dead time which generating an error between the voltage command value and actual output voltage.Those non-ideal factors are analysed in this paper and a method to compansate the equivalent dead time is proposed.3)Due to the rank deficient problem could not been solved while the quantity of parameters bing identified are more than two,the parameters to be identified should be chosen to fit the different working condition of the motor.A method to chose the parameters to be identified is proposed to make sure that the chosen parameter could be identified with better accuracy and could be made better use of.The estimators are designed using Extended Kilman-Filter and the simulation results are given to show the efficiency of the above method.4)At last a PMSM experiment platform is built on which the theory research results are verified by conducting the proposed method.Also the estimators designed by EKF are tested which is proved to be able to identify the parameters bothe quickly and accurately enough.