Research Of Vector Control Strategy Without Speed Sensor Used In High-power Asynchronous Motor

Applications can be seen everywhere in the industrial production of high-power Asynchronous motor, this paper mainly applies to the related research of high-power Asynchronous motor speed control system used in crusher. Most of the crushers are used in mine acquisition and cement production and other industrial fields, the power of the drive motor is generally large, so it needs energy-saving control to its speed control system. Traditional V/F control (Constant voltage frequency ratio) can not meet the requirements because of small starting torque disadvantage. However, the installation of speed sensor in the crusher application is not suitable, not only increasing the cost of the system but more likely destroying the original mechanical structure, speed sensorless vector control is now mainstream AC drive system in industrial production.In this paper, it dose system research on high-power AC motor speed sensorless vector control system applied to the crusher. It builds rotor field oriented vector control based on the dynamic mathematical model of the three-phase asynchronous motor, The ability to achieve complete decoupling of the current control is the key factor affecting the performance of vector control. It gives detailed mathematical derivation of the the voltage feedforward decoupling to achieve the complete decoupling control of the system, and makes a comparison from the design of the two current regulators from the dynamic and steady-state characteristics. Then, it presents an improved voltage-flux model as a system of flux observer based on the analyzing and comparing the advantages and disadvantages of the current-flux model and voltage-flux model.Next, it detailedly studies MRAS speed observer, comparing advantages and disadvantages of MRAS based on rotor flux, back-EMF MRAS and instantaneous reactive power, and ultimately selects MRAS speed observer based on the rotor flux as Sensor system speed.Energy-saving operation of the light load condition is required in the case of light load. According to the different characteristics of the three-phase asynchronous motor load,it proposes a power factor loop control method based on the energy buck light load.when the motor is running at light load stage, it switches to the energy-saving control method and to speed sensorless vector control when the motor is running in heavy load.Finally,it builds simulation model of MRAS rotor flux asynchronous motor speed sensorless vector control system in Matlab/Simulink simulation,the results of simulation show the correctness and feasibility of speed sensorless vector control algorithm.On the basis of the theoretical analysis and simulation studies, It builds a low power laboratory experiment platform using DSP and CPLD as the to control core. A large number of experimental verification of the speed sensor and the speed sensorless vector control algorithm is completed, the results show the system has a good dynamic and static performance and anti-load disturbance, and verify the feasibility of high-power asynchronous motor vector control design method used in crusher.