Vector Control System Researching Of PMSM Based On Synovial Observer

Permanent magnet synchronous motors (PMSM) are now gradually replacing DC motors and variable frequency AC motors in applications because of their superior feaures, including wide speed range, high accuracy, great efficiency, and srong adaptability. However, higher requirements of PMSM’s operating performance are proposed with their extensive use in more situations. In traditional speed regulating system, mechanical sensors are needed to locate the rotor position of the motor, updating real-time velocity information. Thus, the cost of motor is increased and the reliability is reduced for the motor with sensors is more vulnerable to external interference. To resolve this problem, more and more attention is being paid to the application of sensorless speed regulating system.This paper mainly studies surface mounted PMSMs. Firstly, the mathematical model of PMSM in different coordinate systems is introduced in detail, and the pulse width modulation technology SVPWM is analyzed. Therefore, the vector control method of stator current optimal theory (id=0) is adopted. Then, based on sliding mode control theory, a second-order observer of stator current, voltage and back electromotive force is designed and improved to estimate the position and speed of the rotor, according to the selected mathematical model of PMSM in the two-phase stationary coordinate system. The improved sliding mode observer overcomes the lag issues generated by a low pass filter in traditional one, enhancing the estimation accuracy of system, thus the control law is easier to implement. A simulation model of vector control system of PMSM is built in the MATLAB/Simulink platform, in which double-loop control structure is empolyed. The simulation results verify the feasibility and high accuracy of the sliding mode observer proposed.To test and verify the simulation results, some experiments have been done. The hardware part mainly includes:DSP TMS320F28335 as core control chip to design control circuit, optocoupler HCPL3120 and HCPL316J to drive the IGBT on and off, and UC3844 to provide a stable voltage for each module. Motor control program is written on Code Composer Studio V4.2 platform, in which hybrid programming of C and assembly language is applied.Then, the feasibilityand strong robustness of the control system are further verified through several experiments, by analyzing the measured waveforms and data.