Variable-structure controller design for electric drives with variable-torque load

Abstract The paper is devoted to the design of a framework to study uncertain nonlinear dynamical plants. We use the results of this study to design a variable-structure control system for the considered plants. Our studies are based on the use of interval methods to take into account possible plant parameters variations and perform a piecewise linear approximation of the plant’s nonlinearity. We offer to replace a nonlinear function, which is used to define a plant’s dynamic with a phase space domain where this function is localized. This allows us to rewrite the initial nonlinear differential equation into piecewise linear form and apply the Laplace-Carson transformation for the considered differential equation to define the generalized transfer function which gives us the possibility to study and design system dynamics. We use a determined piecewise linear interval transfer function to solve the inverse dynamic problem and define the controller’s transfer function which allows for reaching the desired motion tra jectories. We show the use of our approach and its benefits by designing a controller for a ventilator electric drive. Comparison of the designed control system with the known one allows us to claim its high accuracy and energy efficiency.