Estimation, identification, and sensorless control in motion control system

The paper presents the state of the art of motion systems particularly emphasizing both estimation and identification of parameters and control variables of an electric-motor-driven motion system. In a modern electrical drive system, it is required to take not only the electrical aspect but also the mechanical phase into total system consideration. Improvement in electrical aspect needs a variety of information pertaining to electrical machines and power electronic circuits for improving AC variable-speed drives. Important techniques of identification or estimation of parameters and control variables in AC drives are explained. Such information includes machine parameters, flux, speed, position, and so on. Also, the paper shows that there is some theoretical limit of performance. For improvement of the mechanical phase, the disturbance torque is the most important variable to be identified. It is used in motion control systems, for example, in the feedback loop. Various applications are possible by modification of such a basic approach. As a conclusion, the paper shows that the total robustness is attained by integrating advances of control technique on the electrical aspect and the mechanical aspect. There are numerous variations of controller by possible combinations of these two aspects according to applications