AHODFC And Its Application In AC Adjustable-Speed System With Varying Frequency

Up to the present, PID control is the most useful control method for its simple structure, strong robustness. But PID only considers the one-order differential signal of the error signal, and does not consider its high order differentials. And the approach of extracting differential signal is too simple to satisfy high performance requirement. The important property of the modern control theory is depending on model of the controlled plant based on a performance cost. The excessively depending makes the control arithmetic more and more complicated, so it is not easy to apply and spread in practice.The paper discusses the control question of nonlinear system with disturbance that the model is unknown, and the parameters are time-varying. The aim is to offer a control method which try to combine the merit of PID control with the merit of modern control theory.The thesis states the high order differentiator (HOD) that does not depend on the model of the controlled plant. The HOD can extract high quality one-order differential signal and high-order differential signals of the given signal. Then the paper introduces adaptive high order differential feedback controller (AHODFC) based on HOD, which also does not depend on the model of the controlled system. In order to testify its feasibility and practicability, the paper applies the theory to the AC adjustable-speed system with varying frequency.The important work is that we apply the AHODFC to the AC adjustable-speed system with varying frequency based on the existed projection. The industry computer is the controller and the AC motor is the controlled plant. The simulation and practice verify the AHODFC can successively control the AC adjustable-speed system with varying frequency and its parameters can tune easily and its robustness is good. So it has feasibility and practicability.The thesis builds a control interface of the AC adjustable-speed system with varying frequency on VC++, and the control interface can alternate each other strongly and can operate easily and can tune parameters on line. The control interface combines the control arithmetic with import and export drive program, and it can realize the operation of AC motor's start-up, run, stop and speed varietyand so on.