In this paper, a total sliding-mode control (TSMC) scheme is designed for the voltage tracking control of a conventional dc-dc boost converter. This control strategy is derived in the sense of Lyapunov stability theorem such that the stable tracking performance can be ensured under the occurrence of system uncertainties. The salient feature of this control scheme is that the controlled system has a total sliding motion without a reaching phase as in conventional sliding-mode control (CSMC). Moreover, the effectiveness of the proposed TSMC scheme is verified by numerical simulations and realistic experimentations, and the advantages of good transient response and robustness to uncertainties are indicated in comparison with a conventional proportional-integral control system and a CSMC scheme.

Design of Voltage Tracking Control for DC–DC Boost Converter Via Total Sliding-Mode Technique

This paper presents an approach and associated circuitry for harvesting near maximum output from low power sources in the 100 μW range for miniature wireless devices. A set of converter topologies and control approaches are presented together with detailed efficiency analysis and a design example for a buck-boost based energy harvesting converter using commercially available discrete circuitry. Experimental results are presented for harvesting energy from miniature RF and wind power sources operating over a 10:1 input power range from 500 μW to 50 μW. A closed-system efficiency of 65 % at 50 μW output power is achieved, including all control and converter losses. The results demonstrate that useful energy, sufficient to power typical wireless sensors, can be harvested from miniature sources that output less than 100 μW at a few hundred mV.

Resistor Emulation Approach to Low-Power Energy Harvesting

A new switching control algorithm based on state trajectory approximation is proposed to regulate the output voltage of a representative second-order DC-DC converter - the boost converter. The essence of the proposed algorithm is to trap the system into a stable limit cycle while ensuring the required voltage regulation. Unlike some of the earlier algorithms, the concept is applicable to both continuous and discontinuous current modes of operation, making it viable over a wide operating range under various load and line disturbances. A hybrid-automaton representation of the converter is used to perform the analysis, and the control problem is simplified to a guard-selection problem. Guard conditions, governing the transition of the converter operation from one discrete state to the other in a hybrid-automaton representation, are derived. The hybrid-automaton-based control system is implemented by using the state flow chart feature of MATLAB, and extensive simulations are carried out to check the suitability of the algorithm. The hybrid control law is also validated in real time by using a laboratory prototype. The experimental and simulation results prove the effectiveness of the proposed control law under varying line and load conditions.

A Hybrid Control Algorithm for Voltage Regulation in DC–DC Boost Converter

Finite-time stability concerns the boundness of system during a fixed finite-time interval. For switched systems, finite-time stability property can be affected significantly by switching behavior; however, it was neglected by most previous research. In this paper, the problems of finite-time stability analysis and stabilization for switched nonlinear discrete-time systems are addressed. First, sufficient conditions are given to ensure a class of switched nonlinear discrete-time system subjected to norm bounded disturbance finite-time bounded under arbitrary switching, and then the results are extended to H∞ finite-time boundness of switched nonlinear discrete-time systems. Finally based on the results on finite-time boundness, the state feedback controller is designed to H∞ finite-time stabilize a switched nonlinear discrete-time system. A numerical design example is given to illustrate the proposed results within this paper.

H∞ finite-time control for switched nonlinear discrete-time systems with norm-bounded disturbance

In this study, an adaptive fuzzy-neural-network control (AFNNC) scheme is designed for the voltage tracking control of a conventional dc-dc boost converter. First, the description of the circuit framework of a conventional boost converter and system modeling is introduced. Then, a total sliding-mode control (TSMC) strategy without the reaching phase in the conventional SMC is developed for enhancing system robustness during the transient response of the voltage control. In order to alleviate the control chattering phenomena caused by the sign function in the TSMC design and relax the requirement of detailed system dynamics, an AFNNC scheme is further investigated to imitate the TSMC law for the boost converter. In the AFNNC scheme, online learning algorithms are derived in the sense of Lyapunov stability theorem and projection algorithm to ensure the stability of the controlled system without the requirement of auxiliary compensated controllers despite the existence of uncertainties. The output of the AFNNC scheme can be easily supplied to the duty cycle of the power switch in the boost converter without strict constraints on control parameters selection in conventional control strategies. In addition, the effectiveness of the proposed AFNNC scheme is verified by realistic experimentations, and its advantages are indicated in comparison with the TSMC strategy.

Adaptive Fuzzy-Neural-Network Design for Voltage Tracking Control of a DC–DC Boost Converter

Buck converter is modelled as a hybrid automaton for the purpose of designing an appropriate control law to regulate its output voltage. The circuit when operated in continuous current mode is pulled into a limit cycle, specified by the regulation specifications, although the switching frequency varies with the load. On the other hand, under light-load conditions, the circuit is pulled into a fixed-frequency limit cycle in discontinuous current mode to satisfy the regulation criteria. Therefore, the controller design is generic in the sense that the required regulation is met throughout the operating range of the buck converter. The control problem is simplified as a guard selection problem and guards, defining the discrete states, are derived using a simple circuit theoretical approach, by imposing certain regulation and control constraints. Satisfactory operation of the buck converter under the proposed scheme is demonstrated using computer simulations and laboratory experiments. The suitability and simplicity of the proposed control scheme over a wide range of disturbances is highlighted.

Hybrid control approach for the output voltage regulation in buck type DC-DC converter

The control of DC-DC converters, in particular the boost converter, has been the focus of research for nearly 3 decades. Several attempts have been made to design a suitable controller for the boost converter. But these designs either suffer from model inaccuracy or their inability to apply to both continuous and discontinuous current modes (CCM and DCM). In this paper, a hybrid control scheme, based on hybrid automaton, is proposed for the output voltage regulation of a boost converter. Though the emphasis in this paper is on DCM, the scheme is applicable to both CCM and DCM operation. A safe area around the operating point is determined in the state space to ensure the stability of inter-mode switching. The safe area and the steady state set point are dynamic in the sense that they vary under various line and load disturbance conditions. Then, a suitably designed control algorithm prevents the system states from moving outside the safe area. Different load and input voltage disturbance conditions are simulated in MATLAB/SIMULINK and the results are presented to demonstrate the suitability of the controller. The transient and steady state performance of the closed loop control is found to be satisfactory.

Hybrid Control of a Boost Converter Operating in Discontinuous Current Mode

A tri-state converter has three controllable switches and hence has more operating flexibility. This also brings additional control design flexibility when viewing the converter as a hybrid dynamical system. The operational and control design flexibility of a tri-state boost converter is explored in this paper to control its output voltage. The analysis and control design for the converter is based on an exact hybrid automaton model. The hybrid control design is carried out to ensure the required voltage regulation and switching stability. Using a system theoretical approach, a geometrical region in the state plane around the set point is determined as a stable 'safe-set' by ensuring that a vector field of the system pointing towards the set point always exists to ensure the stability of switching in the converter. Within this stable region, the guards for the hybrid automaton model are determined as the switching control law to satisfy the regulation requirements. The control algorithm is tested using a model of the tri-state boost converter constructed in MATLAB/SIMULINK environment. Modeling, analysis, control design and simulation results are presented. Using the proposed control scheme, it is found that the tri-state converter can work with a wide range of loads and input voltages without compromising on regulation requirements.

Hybrid Control of a Tri-state Boost Converter

In a Single Inductor Double Output (SIDO) boost converter, power is fed to both the outputs through the same inductor and hence the control requirements on output voltages are inter-dependent, causing complexity in modeling and control design of such converters. But, there is some flexibility in disguise due to the increased number of controlled devices and storage elements. This is utilized in this paper, to arrive at different hybrid automaton models for representing the SIDO boost converter. The features of each representation are highlighted. For these models, a safe spherical region around the required set point is identified using the stability requirements for a given set of disturbances. Inside the safe region, hybrid control laws are proposed to regulate the two different outputs at their required levels. Simulation studies are carried out in MATLAB/SIMULINK and the results are presented. The response of the SIDO converter, under various disturbances, is found to be satisfactory under the proposed control scheme.

C. Sreekumar

Papers

A Hybrid Control Algorithm for Voltage Regulation in DC–DC Boost Converter

Hybrid control approach for the output voltage regulation in buck type DC-DC converter

Hybrid Control of a Boost Converter Operating in Discontinuous Current Mode

Hybrid Control of a Tri-state Boost Converter

On the hybrid automaton models and control synthesis of a single inductor, double output boost converter