M. Lopez

Current distribution control design for paralleled DC/DC converters using sliding-mode control

This paper shows the analysis and design of a parallel-connected converter system using sliding mode control techniques. The design is particularised for a system that consists of N boost converters and a current feedback loop based on a proportional-integral compensator of the output voltage error. The paper emphasises the advantages of the sliding-mode control over the classic design method based on small-signal models, thus providing an effective and robust means of controlling nonlinear multi-input converters. The design is based on the Utkin conditions, which permit us to know the regions under which a sliding mode exists. This fact allows us to design the compensator and to introduce some modifications in the control loop that avoids input-current overshoots during the system startup. Simple design expressions are obtained and verified with simulation and experimental results, thus showing the improvements achieved with the proposed modifications.

Sliding-mode-control design of a high-power-factor buck-boost rectifier

This paper presents multi-input sliding-mode control schemes for unity-power-factor rectifiers based on buck-boost converters. The proposed controllers can effectively improve the tracking performance of the line current and the output voltage regulation. The sliding surfaces are designed by imposing a desired dynamic behavior on the system, which allows us to determine the main parameters in designing the sliding-mode controller. This results in fast controllers which provide both robustness, with regard to external disturbances, and a good dynamic response of the output voltage.

Interleaving of parallel DC-DC converters using sliding mode control

This paper introduces a new approach to interleaving parallel power converters using a multi-input sliding-mode control scheme. The control approach is based on sliding surfaces which naturally provide interleaving between cells of a modular power supply system. Moreover, the sliding surfaces provide equal current distribution among the power converter modules and a regulated voltage in the output. The technique is also effective if there is a varying number of cells in the system, each as the failure of one or more cells. Simulation and experimental results are presented for a parallel structure based on three buck power converters.

A systematic method to design sliding mode surfaces by imposing a desired dynamic response [rectifier control]

A systematic method applied to design sliding mode surfaces is described. The design technique allows to find a simple surface for an specific desired dynamic response of the system. This design technique is specially interesting in tracking problems such as unity-power-factor rectifiers.

Dynamic response optimization of quantum series-parallel resonant converters using sliding mode control

A novel design methodology of sliding mode control schemes for quantum resonant converters is presented. The method is based on the imposition of a specified output-voltage dynamic response, and it provides a set of sliding surfaces guaranteeing high robustness and large-signal stability. Among these schemes, the final configuration is selected taking into account a simple practical implementation. Simulation and experimental results are reported, confirming the validity of the proposed solution.

An averaged large-signal modeling method for resonant converters

An averaged large-signal modelling method for resonant converters is presented, which is based on the classification of the state variables according to their dynamic behaviour. The modelling technique is applied to a series-parallel resonant converter, which is controlled for switching at zero-resonant current. Based on the averaged model, a sliding mode controller for this resonant converter is proposed, which provides robustness in relation to external disturbances and a good dynamic response of the output voltage.

A new family of single-stage high-power-factor AC/DC converters

A new family of single-stage unity power factor converters is proposed. Although they operate in continuous conduction mode, a single switch is able to control the line current and the output voltage at the same time. The proposed structures are based on a three-state switch whose switching and conduction losses are similar to those of a conventional device.

A sliding mode controller for the current-source parallel-resonant converter with zero-voltage switching

This paper presents a new switch control strategy for the current-source parallel-resonant converter, which provides zero-voltage switching conditions. To implement the new control technique, a sliding mode controller is proposed. The controller design is carried out using an averaged large-signal model of the converter, and allows determination of the main constraints of the controller parameters. The controller provides fast transient response, absence of steady-state errors in the output voltage and a robust output voltage response in relation to the input voltage and load disturbances.

Multi-input sliding mode control for parallel-connected series resonant converters

A multi-input sliding-mode control scheme for a multi-module parallel power converter system is investigated. The system is based on series resonant power converters operating at resonant frequency and switching at zero resonant current. An averaged circuit model for each module is derived which allows a description of the dynamic behavior of this power converter under large-signal conditions. This model is used for designing a simple multi-input sliding mode controller for a modular power system. Using this control strategy makes the dynamic response of the system correspond to a second-order linear behavior and the asymptotic stability in the global state space can be guaranteed.

Control loop design of parallel connected converters using sliding mode and linear control techniques

This paper shows the design of a parallel connected converter system using both linear control techniques applied to small-signal models and sliding mode control. The paper presents a sliding mode strategy as an alternative design method. This different approach allows to endow the system with prominent dynamic characteristics. Analysis and design consideration are investigated in the case of sliding mode control.