Research On Active Disturbance Rejection Control Strategy For Cascade Speed Drive System By Chopper

The technology of slip power recovery controlled by chopper for winding induction motor has been widely applied in high-voltage large-capacity motor. But the conventional control system is difficult to get a good control performance for speed regulation or steady speed, when running in some operation conditions as speed demand change, load disturbance, especially for some impact load disturbance, because of the mathematic model of motor drive speed control system has the nonlinear and time-varied dynamic characteristics.Auto-Disturbance-Rejection-Control (ADRC) is a new type nonlinear technology, which is an increasing concern in control engineering. ADRC inherits and develops the error control kernel of PID regulator. Using ADRC,the control performance of complex systems can be improved by mediating the conflicts between overshoot and rapidity, due to the organization of the transition process, reasonable extraction of differential signal, the real-time estimation and compensation of the unknown or uncertainties total disturbances, and nonlinear control law.Thus, a double-closed-loop control system based on ADRC is presented to improve the dynamic performance of slip power recovery drives, after studying the working principle and mathematical model of cascade speed control system with chopper. The main research works have carried out as follows.1)Base on the average principle equivalent circuit, the varying parameter dynamic model and simulation models of the cascade speed control system with chopper are established. Those can describe the dynamic characteristics of this system in the whole speed range by reflecting the parameters change with the motor speed and rotor rectified current, and can be used as a theoretical basis for engineering design.2)A computer aided design software for ADRC is developed. Using MATLAB as the experimental platform, a user-defined ADRC Block library is created by the way of developing MATLAB function files for special nonlinear functions, designing system functions for special dynamic algorithms, then masking some user defined subsystems for Control Law combination and ADRC algorithms which often used. The simulation model of ADRC can be built as module block form. It is a useful tool for searching and simulation of ADRC technology.3)The speed control system of slip recovery power motor is designed based on ADRC technology and this method is firstly proposed. The new type of double closed loop control system for cascade control motor is designed by using ADRC as auto speed regulator and PID as auto current regulator to enhance the control performance. The algorithm design and system simulation has completed, then the simulation experiments of many disturbances for driving impacting load or square torque load are made to achieve the objective of improving system dynamic performance.4)The parameters of ADRC are optimized by immune genetic algorithm, and the optimized results are applied in cascade speed control system.