Modeling The Non-linear Under Variable Load Double Loop Dc Motor Control System

With the development of the advanced automation technology, the DC motors are widely used in intelligent systems which need high precision control, while the double loop DC motor control system (DLM) is the typical scheme of DC motor control system. The DLM contains nonlinearity which including non-linear saturation is an important research direction of DC motor control system, and the identification of the closed-loop system is always a hot and difficult issue of model identification research in theory.The DLM model mainly includes the ideal model, the second-order linear model and the non-linear model in constant load or without considering the load disturbance, and so on. Owing to the saturated nonlinear of the internal of closed-loop system, the dynamic response of the ideal model and the second-order linear model is highly different from the real system, and the operation conditions are different between the ideal model which has constant load or without considering the load disturbance and the real system. In addition, the model in other literature are complex, verifying only in the simulation condition, lacking of support by the test results of the real system. In view of the above question, this paper mainly carried on the following research:â‘ We made a deep study on the mechanism of the DLM when the load of motor changed, got the mechanism model of the system. Through the analysis of the main dynamic characteristic and using the method of"quasi-equivalent"modeling, we got the DML non-linear state space model under the variable load and the gradual disturbances back EMF.â‘¡A parameter identification method which used in the non-linear state space model of the DLM under variable load was proposed. The method took the DLM and the load as a whole, and we did the parameter identification with improved genetic algorithm to this DLM model.â‘¢Mechanical properties of different types of load was analyzed, a DC motor experimental test platform which is used to study DC motor with variable load was developed. The constant inertia moment formed the changes of torque load on this platform which is composed of the DC motor, the encoder unit, the planetary gear box unit, the TMS320X2812 DSP unit, the servo drive unit, the interface unit, the speed detection unit and other components. The platform verified that the proposed variable load DC Motor Speed Control System with nonlinear state space model and parameter identification method is effectiveness. Through the above research, this paper presents a variable load DC Motor Speed Control System of nonlinear state space model and the model parameters identification method of integration, and the actual experimentals shows that the method is practical and effective.