Research On Electrical Parameters Identification Of Permanent Magnet Synchronous Motor Based Servo System

Due to advanced operating efficiency,strong starting torque and high power/torque density,permanent magnet synchronous motors(PMSMs)are widely applied in the servo systems.The parameters such as stator resistance,inductance and permanent magnet flux linkage are particularly important for the controller design and condition monitoring of the motor servo systems.When the motor works,dragging the load,the current increases,so the temperature of the motor stator and rotor increases,and the air gap magnetic field appears saturated.Obviously,the electrical parameters get changed,resulting in poor motor control accuracy.To solve the above-mentioned problems,this paper studies the identification algorithms of the PMSM’s electrical parameters(resistance,inductance,permanent magnet flux linkage)and the compensation scheme of inverter nonlinear factors,proposes an optimization algorithm to improve the accuracy of parameter identification and verifies these algorithms by establishing an experimental platform.The main contents are as follows:(1)The PMSM’s mathematical model and principle of coordinate transformation are analyzed.The online identification equations are derived and the offline identification algorithm for PMSM’s electrical parameters is given.(2)The voltage distortion caused by the nonlinear factors of the voltage source inverter is analyzed and then an experimental platform is established to implement the experimental researches on inverter nonlinear compensation methods.Also,the suppression effect of voltage distortion and sixth harmonic of current at different motor speeds shows the VSI compensation result by setting the compensation time to adjust the turn-on / turn-off time of the switch.(3)The online identification of PMSM’s electrical parameters based on model reference adaptive algorithm is studied,with the resistance,inductance and permanent magnet flux linkage identified non-simultaneously.The robustness of the parameter identification adaptive laws is improved by comparing the sensitivities to the motor speed.In order to improve parameter identification accuracy,the influence of the selection of the initial resistance value on the parameter identification result is analyzed.(4)The PMSM’s the electrical multi-parameter simultaneous identification algorithm based on the least squares algorithm is studied,with the mathematical principle of the least squares method,recursive least squares method and recursive least squares method with forgetting factors analyzed,and the effectiveness of the algorithm verified experimentally.In order to improve the identification accuracy,an optimized least squares identification algorithm suitable for surface-mounted permanent magnet synchronous motor parameter identification is proposed.(5)The online PMSM’s identification model based on the bistable constant-torque algorithm and application conditions of the short-term injection current on the d-axis are studied.Then,the effectiveness of the algorithm,the conclusion about the compensation strategy of the inverter nonlinear factors and the calculation method of its equivalent resistance are validated experimentally.