Research And Design Of Controlling Method On Sensorless PM AC Servo System

Permanent Magnet Synchronous Motors (PMSM) are widely applied in differentdomains such as numerical controlled machine tools and industrial robots because oftheir several inherent advantages. Also, a significant attention in the development ofsensorless strategies has been paid to eliminate the position and speed sensors. In thispaper, the key problems of sensorless PMSM are investigated in detail. And based onthose, a feasible method for shaft sensorless PMSM drive system is presented.Based on the comprehensively deep research on the PMSM's mathematic model, anovel model of inverter-fed PMSM is proposed. The rationality of the controlstrategies can be validated by using this model and then the process of the experimentcan be expedited significantly.Sensorless PMSM Drive With Extended Kalman optimum Estimation of Speedand Rotor Position is proposed in this paper. The Kalman filter's basic principle isstudied in detail and linearization of nonlinear equation of motor driver is obtainedusingα ? βreference frame. Real-time optimal estimation online of motor position θand speed ω utilizing Extended Kalman filter (EKF) is accomplished. This methodhas rather good motor position and speed tracking performance. Moreover,ability ofanti-disturbance of load is the remarkable feature of this system. Its validity is verifiedby the simulation results.Based on the analysis of the mathematical model of PMSM in the estimationframe, a new state estimation method for sensorless PMSM vector control system isdesigned in this paper. Using the "electrical steady state" operation concepts, theactual rotor position as well as the motor speed can be estimated accurately duringtransit states. The error compensation algorithm of the state estimation is presentedthrough analyzing the parameter dependency of the proposed system. This method hassimpler control algorithms and little computational burden and can be easilyimplemented in digital control system. Simulation and experiment results demonstratethe feasibility of the proposed strategy.The starting procedure is a problem under sensorless drives since no informationis available before starting. As a solution, a new starting method which uses constantflux to detect initial rotor position at standstill is presented in this paper. Using thisnew method we can get the initial position of rotor accurately and make the startingmore steadily.Grounded on the work above, a real system includes TI's DSP TMS320LF2407Aas central control unit is developed, and the monitor control system based onController Area Network(CAN) bus is designed.