| In today's world,with the continuous innovation and breakthroughs in power electronics technology and the increasingly mature and perfect for control system,frequency conversion speed regulation is applied widely in various fields.As the main body of speed control system,Permanent Magnet Synchronous Motor(PMSM)plays an important role.Compared with the DC motor and asynchronous motor,it has its own unique characteristics: without brush and slip ring,simple structure,both economical and safe and reliable;rotor without excitation winding,save the excitation current,small volume,power factor and efficiency are very high.Therefore,whether it's from military industry or civilian,especially in the field of high accuracy and fast response control,it can be seen everywhere.Combined with power electronics,microelectronics and modern control technology,it represents the development direction of motor in the new century.Accurate initial position detection is the key to the smooth and stable starting of the closed loop control of permanent magnet synchronous motor.When the new energy vehicle and the servo drive drive system are used,it is often expected that the permanent magnet synchronous motor can realize the precise control of "low speed,large torque,light load and high speed",and the motor needs to be transported to the state of weak magnetic speed regulation.This paper focuses on these issues.The contents of the study are as follows:1.On the laboratory 2.2kW permanent magnet synchronous motor vector control experimental platform,the experiment results of vector control in the full speed range of motor were perfected.2.On the basis of mathematical model and related theory,the initial position detection of permanent magnet synchronous motor is carried out by using the prepositioning method and voltage vector injection method.The experimental results verify the correctness of the method.3.Aiming at the problem that the given value of axial current can not be solved in the control strategy of MTPA(Maximum Torque Per Ampere Control)control strategy for permanent magnet synchronous motor(PMSM),a method of curve fitting for solving high order equation is proposed,and the given value of the AC axis current at different rotational speed requirements is obtained.The simulation model is built under MATLAB/Simulink environment,and the motor starting performance,speed regulation performance and load disturbance performance are simulated.The simulation results show that the method is easy to implement and has high control accuracy.4.The gradient descent method is used to speed control of the built-in permanent magnet synchronous motor.The voltage difference and the gradient of torque are used to calculate the current compensation value,and the closed-loop voltage control is realized.By monitoring the amplitude and phase angle of the synthetic voltage vector,the natural transition of different modulation regions is completed in the weak magnetic speed control high speed area,and the test is carried out under the MATLAB/ Simulink environment.The simulation results show that the over modulation control scheme proposed in this paper makes the motor improved the stator voltage and output torque at a given rotational speed,and expanded the steady magnetic flux region of PMSM under a certain load torque.5.Further perfected the experimental platform of 2.2k W permanent magnet synchronous motor control system and the program of vector control.The weak magnetic speed regulation program based on MTPA was written.The weak magnetic speed regulation of a certain range under the rated load of permanent magnet synchronous motor was realized on the experimental platform.The results proved the correctness and the feasibility of the method of flux weakening. |
PDF Full Text Request