Control Theory And Control Engineering

With the appearance all kinds of the new electronic power device and microprocessor and the advanced controlling theories be presented, which have greatly promoted the development of AC motor speed control system. The AC motor's controller which haves high accuracy, wide speed range and good performance of controlling can be realized. Vector Control is based on the theory developed of the electrical, electromechanical energy conversion principle and vector coordinate transformation. Its thought of controlling is converting asynchronous motors as DC motor to control or even better. Through the coordinate transformation, the stator current vector is decomposing two DC parts which orientated as the rotator magnetic field and controlled respectively. Thus magnetic flux and torque are decoupled. It controls the asynchronous motor as a synchronous way. Therefore, the vector control technology has been widely used in high-performance asynchronous motor speed control system.First of all, the vector control theory and its decoupling are introduced on the foundation of the mathematical model of asynchronous motor. The variables in 3-phase static coordinates are converted into the variables in 2-phase rotating coordinates and the components between torque and magnetic field of stator winding current are decoupled which uses the rotor-field-oriented technology. Thus, the asynchronous motor speed control is achieved. The structure diagram of vector control system which combines the current model of motor is given and provides the theoretical basis for the design of SVPWM vector control system. Based of SVPWM principle, the SVPWM software was designed. Asynchronous motors control systems have the characteristics of Nonlinear, strong coupling, parameters-varying and rapid response. the design of vector control systems' current controller using fuzzy-PI control algorithm, speed controller using fuzzy factor self-adjusting algorithm constitute double loop intelligent control systems to effectively control motor speed.Secondly, application of the principle of vector control, using digital single processor TMS320LF2407 of TI, which is special for motor control, as the core of system, using SKBPC3512 as the rectifier, using the intelligent power module PM25RLA120 of Mitsubishi Corporation as the inverter, using space voltage pulse width modulation technology, design digital PWM speed control system and construct an asynchronous motor for the vector control system based on DSP. In this paper, the main circuit, control circuit and protective circuit are designed in detail. In order to improve the capability of Anti-jamming, valid measures are taken. The modularization design is adopted in software so that it can be amended and replanted easily. The SVPWM vector control strategy is carried out. At last, the hardware and software is debugged. The experiment results expressed that the design of hardware and software in this paper is reasonable and valid.Finally, the controller is simulated respectively with the SIMULINK. module in the MATLAB. From the simulation results, the control strategy of this paper not only designs easily and avoids the restriction from the complex mathematical model of the controlled object, but also the rapidness of the system torque response and the control accuracy of speed are improved. It also has the good robustness against the perturbation of the rotor parameter. Thus, the static and dynamic characteristics of the system are ensured validly, which satisfy the requirement of engineering.