Observer based feedback control of 3rd order LCC resonant converters

The paper considers specific issues related to the design and realisation of observer-based feedback of isolated output voltage for resonant power converters. To provide a focus to the study, a 3rd order LCC converter is employed as a candidate topology. It is shown that whilst resonant converters nominally operate at high switching frequencies to facilitate the use of small reactive components, by appropriate pre-conditioning of non-isolated resonant-tank voltages and currents, the resulting observer can be implemented at relatively low sampling frequencies, and hence, take advantage of low-cost digital hardware. Experimental results are used to demonstrate the accuracy of observer estimates under both transient and steady-state operating conditions, and to show operation of the observer as part of a closed-loop feedback system where the LCC resonant converter is used as a regulated power supply

Local control of multiple module converters with ratings-based load sharing

Multiple module dc-dc converters show promise in meeting the increasing demands on ef- ficiency and performance of energy conversion systems. In order to increase reliability, maintainability, and expandability, a modular approach in converter design is often desired. This thesis proposes local control of multiple module converters as an alternative to using a central controller or master controller. A power ratings-based load sharing scheme that allows for uniform and non-uniform sharing is introduced. Focus is given to an input series, output parallel (ISOP) configuration and modules with a push-pull topology. Sensorless current mode (SCM) control is digitally implemented on separate controllers for each of the modules. The benefits of interleaving the switching signals of the distributed modules is presented. Simulation and experimental results demonstrate stable, ratings-based sharing in an ISOP converter with a high conversion ratio for both uniform and non-uniform load sharing cases

Hysteresis and Delta Modulation Control of Converters Using Sensorless Current Mode

Sensorless current mode (SCM) is a control formulation for dc-dc converters that results in voltage-source characteristics, excellent open-loop tracking, and near-ideal source rejection. Hysteresis and delta modulation are well-known, easy-to-construct large-signal methods for switched systems. Combining either large-signal method with SCM creates a controller that is simpler and more robust than a pulse-width modulation (PWM) based controller. The small-signal advantages of PWM-based SCM are retained and expanded to include converter response to large-signal disturbances. These approaches can be used with any converter topology over a broad range of operating conditions. In the present work, hysteresis and delta modulation SCM controllers are derived and simulated. Extensive experimental results demonstrate the large-signal behavior of both control schemes

Design and Implementation of Takagi-Sugeno Fuzzy Tracking Control for a DC-DC Buck Converter

This paper presents the design and implementation of a Takagi-Sugeno (T-S) fuzzy controller for a DC-DC buck converter using Arduino board. The proposed fuzzy controller is able to pilot the states of the buck converter to track a reference model. The T-S fuzzy model is employed, firstly, to represent exactly the dynamics of the nonlinear buck converter system, and then the considered controller is designed on the basis of a concept called Virtual Desired Variables (VDVs). In this case, a two-stage design procedure is developed: i) determine the reference model according to the desired output voltage, ii) determine the fuzzy controller gains by solving a set of Linear Matrix Inequalities (LMIs). A digital implementation of the proposed T-S fuzzy controller is carried out using the ATmega328P-based Microcontroller of the Arduino Uno board. Simulations and experimental results demonstrate the validity and effectiveness of the proposed control scheme

Nonlinear Analysis and Control of Interleaved Boost Converter Using Real-Time Cycle to Cycle Variable Slope Compensation

Switched-mode power converters are inherently nonlinear and piecewise smooth systems that may exhibit a series of undesirable operations that can greatly reduce the converter's efficiency and lifetime. This paper presents a nonlinear analysis technique to investigate the influence of system parameters on the stability of interleaved boost converters. In this approach, Monodromy matrix that contains all the comprehensive information of converter parameters and control loop can be employed to fully reveal and understand the inherent nonlinear dynamics of interleaved boost converters, including the interaction effect of switching operation. Thereby not only the boundary conditions but also the relationship between stability margin and the parameters given can be intuitively studied by the eigenvalues of this matrix. Furthermore, by employing the knowledge gained from this analysis, a real-Time cycle to cycle variable slope compensation method is proposed to guarantee a satisfactory performance of the converter with an extended range of stable operation. Outcomes show that systems can regain stability by applying the proposed method within a few time periods of switching cycles. The numerical and analytical results validate the theoretical analysis, and experimental results verify the effectiveness of the proposed approach

Modeling and Nonlinear Control of dc–dc Converters for Microgrid Applications

This paper proposes a high-performance control strategy for dc–dc converters supplying combined loads (constant current/power, and/or linear loads). This strategy combines a feedback law with a feedforward compensation. The feedback law is based on full feedback linearization, which guarantees that zero dynamics are avoided. To design a single controller for the three basic converter topologies (i.e., buck, boost and buck–boost), a unified model for these converters is introduced. From the resulting combined control law, the specific control law for each type of converter can be obtained by setting three constant coefficient to 0 or 1. The feedforward compensation is based on the estimated values of the load obtained via a nonlinear observer. The main advantage of this unified approach is that it is implemented by using a single algorithm which can be executed in a dedicated hardware, for instance, a single integrated circuit, providing a unified solution for the control of the mentioned topologies. The good performance of the proposed scheme is verified through simulations and tested via experimental application cases, concluding that this is a good unified solution to control dc–dc converters used in microgrid applications.Fil: Solsona, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Gómez Jorge, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Busada, Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentin

Control of power electronic interfaces in distributed generation.

Renewable energy has gained popularity as an alternative resource for electric power generation. As such, Distributed Generation (DG) is expected to open new horizons to electric power generation. Most renewable energy sources cannot be connected to the load directly. Integration of the renewable energy sources with the load has brought new challenges in terms of the system’s stability, voltage regulation and power quality issues. For example, the output power, voltage and frequency of an example wind turbine depend on the wind speed, which fluctuate over time and cannot be forecasted accurately. At the same time, the nonlinearity of residential electrical load is steadily increasing with the growing use of devices with rectifiers at their front end. This nonlinearity of the load deviates both current and voltage waveforms in the distribution feeder from their sinusoidal shape, hence increasing the Total Harmonics Distortions (THD) and polluting the grid. Advances in Power Electronic Interfaces (PEI) have increased the viability of DG systems and enhanced controllability and power transfer capability. Power electronic converter as an interface between energy sources and the grid/load has a higher degree of controllability compared to electrical machine used as the generator. This controllability can be used to not only overcome the aforementioned shortfalls of integration of renewable energy with the grid/load but also to reduce THD and improve the power quality. As a consequence, design of a sophisticated controller that can take advantage of this controllability provided by PEIs to facilitate the integration of DG with the load and generate high quality power has become of great interest. In this study a set of nonlinear controllers and observers are proposed for the control of PEIs with different DG technologies. Lyapunov stability analysis, simulation and experimental results are used to validate the effectiveness of the proposed control solution in terms of tracking objective and meeting the THD requirements of IEEE 519 and EN 50160 standards for US and European power systems, respectively