Research On Parameter Identification Of Three Phase Asynchronous Motor

Asynchronous motors with its small size,low dissipation,simple structure,low cost,quickly occupy the dominant position in the field of modem speed control.In the existing AC speed control method,the vector control independently controls the torque and the excitation component of the asynchronous motor,which effectively improves the control accuracy,and thus has been widely used.The key to vector control lies in the accurate observation of the flux linkage,and the accuracy of the flux linkage depends on various parameters of the motor.Inaccurate parameters can cause the motor's rotational speed to fluctuate and torque oscillation.There are two main reasons for the accuracy of the motor parameters.One is the setting of the motor's initial parameters,and the other is that the temperature rise and magnetic saturation cause a large change in the motor parameters.To solve the above problems,this dissertation studies the off-line parameter identification and on-line parameter identification.Firstly,the mathematical model is simplified on the basis of the mathematical transformation and vector control of the motor,and the excitation and torque components of the asynchronous motor are decoupled.An MRAS vector control system based on rotating magnetic field orientation is proposed.The SVPWM modulation method was used to establish vector control system.to improve bus voltage utilization.Secondly,to improve the accuracy of the motor's initial parameters,the offline parameter identification principle was analyzed.The stator resistance,rotor resistance,and stator leakage inductance were identified by DC and single-phase AC experiments.Under the condition that the motor was idling,rotor mutual inductance.was determined.Then,qualitative analysis of the influence of changes in motor parameters on speed,torque,and flux linkage is performed.For the parameter change problem,an MRAS system that recognizes the rotor time constant,rotor time constantand stator resistance simultaneously is established and validated by a MATLAB simulation tool.Finally,TMS320F28335 is used as the core control chip to build the hardware platform of the speed control system.The hardware architecture,main circuit design and software design for parameter identification are elaborated and analyzed in detail.A series of experiments on the control scheme are performed on the prototype.The experimental waveforms and simulation waveforms are basically the same,indicating that the design method is credible.