Abstract
This paper shows that an optimal preview control system approaches to a decoupled preview control system with input delay time due to processing time where the weighting factors of the control input variables in the quadratic performance index tend toward zero. Therefore, the asymptotic characteristics of the optimal preview control system are clarified by examining the decoupled preview control system. The relations between the design parameters and the responses of the preview control system become clear approximately and the design of the optimal preview control can be simplified by utilizing the properties of the decoupled control system. Further, the proposed design method is applied to a vector control system for induction motor drive. It is impossible to ignore the input delay time in this system because vector control relatively needs quick response and complex calculation. By this application, a trade off between the conditions of the vector control and magnitude of input variables becomes easy. To demonstrate the significance of this proposed method, simulation results are carried out.
