Self‐adaptive fractional‐order LQ‐PID voltage controller for robust disturbance compensation in DC‐DC buck converters

Abstract

This paper presents a state‐dependent self‐tuning fractional control strategy for a DC‐DC buck converter in order to enhance its output voltage regulation and disturbance attenuation capability. The proposed control scheme primarily employs a ubiquitous proportional‐integral‐derivative (PID) controller, where gains are optimally selected using a linear‐quadratic state‐space tuning approach. The optimal PID controller is then augmented with fractional‐order integral and derivative operators in order to improve the controller's degrees‐of‐freedom as well as the system's overall time‐domain performance. The fractional controller's robustness against bounded exogenous disturbances, contributed by the input fluctuations and load‐step transients, is further enhanced by adaptively modulating the fractional‐orders of the integro‐differential operators as a smooth nonlinear function of controlled‐variable's error‐dynamics. An online dynamic adjustment law, comprising of a zero‐mean Gaussian function of error and its derivative, is used to individually update the two fractional orders after every sampling interval. The error derivative is evaluated by measuring the output capacitor's current in order to compensate the noise injected by parasitic impedance. The other controller parameters are tuned via particle‐swarm‐optimization algorithm. The proposed self‐adaptive control strategy renders rapid transits, minimum transient recovery time, and minimal fluctuations around steady state in the response. Its efficacy is validated through hardware in‐the‐loop experiments conducted on a buck converter prototype.

Complex-order PID controller design for enhanced blood-glucose regulation in Type-I diabetes patients

“…The FO-PID control law is formulated by supplementing the conventional PID controller with predetermined fractional orders integral and differential operators as indicated below. 29…”

“…To simplify their implementation, the fractional operators are approximated via the Oustaloup recursive filters. 29 The Oustaloup approach is used to implement the fractional operator as demonstrated below.…”

Robust design of fractional order IMC controller for fractional order processes with time delay

“…Since it was developed, the classical order PID controller has been most often used to control real-time processes. 4,5 This controller has a simple structure that can be easily implemented into the hardware. Since then, a wide range of control techniques has been proposed for the PID controller.…”

“…Hence, the controller must be considered all situations. Since it was developed, the classical order PID controller has been most often used to control real‐time processes 4,5 . This controller has a simple structure that can be easily implemented into the hardware.…”

Sine Cosine Algorithm Assisted FOPID Controller Design for Interval Systems Using Reduced-Order Modeling Ensuring Stability

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