Research On Control Strategy Of Speed Loop Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors are widely used due to high conversion efficiency,high power density,and easy to be controlled.The mathematical model and the main factors affecting the speed loop control performance are introduced in this paper.An optimization scheme is proposed to improve the dynamic response capability of the speed loop.Firstly,the vector control method of permanent magnet synchronous motor is introduced.Then,the control parameters of velocity loop and current loop are theoretically deduced.Therefore,the parameters of controller can be set.The basic principle and implementation method of space vector pulse width modulation algorithm are introduced.Secondly,the delay of speed feedback is proposed as the first factor affecting the performance of the speed loop.Therefore,a reduced-order extended Kalman filter algorithm which based on the composite load torque observer is proposed to reduce the delay of the speed feedback.The detailed theoretical derivation and analysis of the reduced-order extended Kalman filter algorithm are carried out.The advantage of the algorithm is that it simplifies the calculation and improves the dynamic response capability.The feasibility and effectiveness of the proposed algorithm are verified by a large number of simulations and experiments.The proposed algorithm greatly increases the speed loop bandwidth(from 70 Hz to 250Hz).Thirdly,the inertia identification algorithm is studied as another major factor affecting the performance of speed loop.When the motor is making a small vibration,the gradient correction algorithm is used to realize the inertia identification.Finally,the effectiveness of the proposed algorithm is verified by the experiment.The speed loop control parameter self-tuning and the reduced-order extended Kalman filter algorithm are optimized according to the identified moment of inertia.Through the above algorithm,the speed loop bandwidth is increased by 2 times,and operation amount is reduced by 50%.The applicability of the algorithm is improved by the inertia identification which accuracy reaches 0.8%.