Fixed-time sliding mode control method for step-down DC converter based on disturbance upper bound estimation

Abstract

The invention discloses a fixed-time sliding mode control method of a buck type direct current converter based on interference upper bound estimation, which comprises the following steps of: converting an average model of the buck type direct current converter system into a buck type direct current converter error dynamic equation according to a state variable; designing a fixed-time sliding moldsurface according to the state variable so that the state of an initialization system runs to the fixed-time sliding mold surface; defining an uncertain interference item according to the system parameters and the Lyapunov function; designing a self-adaptive fixed-time sliding mode controller according to the error dynamic equation of the buck type direct current converter and the fixed-time sliding mode surface, and estimating an estimated value of the upper bound of an uncertain interference term in the self-adaptive fixed-time sliding mode controller by designing a self-adaptive updating law; so that the adaptive fixed-time sliding mode controller is used for controlling the output voltage of the buck type direct current converter. The method achieves that the output voltage error converges to a neighborhood of the expected reference output voltage in fixed time under the condition of uncertain system parameters, and the upper bound of the convergence time is independent of the initial value of the system state variable.

Description

technical field [0001] The invention relates to a fixed-time sliding mode control method for a step-down DC converter based on an estimation of the upper bound of disturbance, in particular to a fixed-time sliding mode control method for a step-down DC converter with uncertain system parameters. Background technique [0002] DC converters are widely used in DC equipment that requires DC voltage change or power supply, such as industrial electronic equipment, communication equipment, and DC motor drivers. Buck converter is one of the main topologies of DC converters used to convert high input voltage to low output voltage. Since buck converters are nonlinear time-varying systems, the design of high-performance control strategies is usually a challenging problem. At present, many nonlinear control methods have been applied to buck converters, such as sliding mode control, neural network control, and fuzzy control. Among many methods, sliding mode control has received extensi...

AI Technical Summary

Problems solved by technology

[0008] In order to solve the problem of output voltage control of the step-down DC converter with uncertain system parameters, the present invention proposes a fixed-time sliding mode control method for the step-down DC converter based on the estimation of the upper bound of the disturbance. Based on the adaptive control theory, the adaptive law is designed to estimate the upper bound of the uncertain disturbance online, and a fixed-time adaptive controller is designed through the estimated value, so that the system output voltage error can be controlled within a fixed time when the system parameters are uncertain. converges to the neighborhood containing the reference expected output voltage, and its convergence time has nothing to do with the initial value of the system state variable

Images