Modeling And Identification Of Brushless DC Motor System

The brushless DC motor (BLDCM) is a new style motor which is grown up fastly along with the power electronics, Micro-electronics Technology, New motor control theory and new permanent magnet materials. BLDCM has lots of merits, such as high torque, small cubage, simple configuration, high reliability and so on. With the development of brushless DC motor in the field, the demand for control system of the motor is increasing. We consider not only the low-cost, the reasonable control algorithm, but also good control performance and short development cycle. Actually, the Control system design is often in the case of offline. It is a key issue for designers What kind of model to replace the actual system in the process of controller design.Firstly, this dissertation analyzes deeply in the components and mechanism of the Brushless DC motor system, especially in the main dynamic characteristics, the process of commutation ,torque ripple and so on. Based on the different characteristics of motor in the different phase of commutation, the model of brushless direct current motor system has been reduced to a simple state space model which is mutative according to period of time. Further, based on the real rotate speed response, the improved genetic algorithm has been indicated to accurately identify model parameters.For verifying the validity of this method, we have designed a real-time controller system based on the STM32 Micro-controllers. The hardware platforms include micro-controllers, power driver and inversion circuit, current detection circuit, voltage detection circuit, power circuit and others. Throuth the software design, rotor position detection, motor starting, current sampling, the calculation of speed, current regulation, speed regulations had been completed. Based on the platform, we have obtained the required samples for building modal. Then, through the contrastive experiments between this model and other common model , it is obvious that the structure of the model is reasonable,and parameters'identification is precise.Moreover, we design the speed control simulation platform of Brushless motor base on the modal. Common PID controller is used to verify the effectiveness of the platform, and the comparion of simulation data and the actual recorded data turn out that designed control algorithm based on the simulation platform can be directly applied in practice.