Bisection Algorithm based Indirect Finite Control Set Model Predictive Control for Modular Multilevel Converters

In this work, an idea based on the bisection algorithm is used to reduce the computational burden of indirect finite control set model predictive control (FCS-MPC) for modular multilevel converters (MMCs). The proposed method greatly reduces the search space for reaching the optimal insertion index (number of submodules to be inserted). Therefore, the strategy proposed offers similar steady-state and dynamic performance compared to full indirect FCS-MPC at a much lower computational burden. A new cost function is also proposed for indirect FCS-MPC which eliminates the need for an outer loop or additional control of differential current to regulate the summation voltages in each arm. The results of the proposed strategy are validated through simulations in MATLAB/Simulink.acceptedVersio

Model Predictive Control for Power Converters and Drives: Advances and Trends

Model predictive control (MPC) is a very attractive solution for controlling power electronic converters. The aim of this paper is to present and discuss the latest developments in MPC for power converters and drives, describing the current state of this control strategy and analyzing the new trends and challenges it presents when applied to power electronic systems. The paper revisits the operating principle of MPC and identifies three key elements in the MPC strategies, namely the prediction model, the cost function, and the optimization algorithm. This paper summarizes the most recent research concerning these elements, providing details about the different solutions proposed by the academic and industrial communitiesMinisterio de Economia y Competitividad TEC2016-78430-RConsejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) P11-TIC-707

Design and Advanced Model Predictive Control of Wide Bandgap Based Power Converters

The field of power electronics (PE) is experiencing a revolution by harnessing the superior technical characteristics of wide-band gap (WBG) materials, namely Silicone Carbide (SiC) and Gallium Nitride (GaN). Semiconductor devices devised using WBG materials enable high temperature operation at reduced footprint, offer higher blocking voltages, and operate at much higher switching frequencies compared to conventional Silicon (Si) based counterpart. These characteristics are highly desirable as they allow converter designs for challenging applications such as more-electric-aircraft (MEA), electric vehicle (EV) power train, and the like. This dissertation presents designs of a WBG based power converters for a 1 MW, 1 MHz ultra-fast offboard EV charger, and 250 kW integrated modular motor drive (IMMD) for a MEA application. The goal of these designs is to demonstrate the superior power density and efficiency that are achievable by leveraging the power of SiC and GaN semiconductors. Ultra-fast EV charging is expected to alleviate the challenge of range anxiety , which is currently hindering the mass adoption of EVs in automotive market. The power converter design presented in the dissertation utilizes SiC MOSFETs embedded in a topology that is a modification of the conventional three-level (3L) active neutral-point clamped (ANPC) converter. A novel phase-shifted modulation scheme presented alongside the design allows converter operation at switching frequency of 1 MHz, thereby miniaturizing the grid-side filter to enhance the power density. IMMDs combine the power electronic drive and the electric machine into a single unit, and thus is an efficient solution to realize the electrification of aircraft. The IMMD design presented in the dissertation uses GaN devices embedded in a stacked modular full-bridge converter topology to individually drive each of the motor coils. Various issues and solutions, pertaining to paralleling of GaN devices to meet the high current requirements are also addressed in the thesis. Experimental prototypes of the SiC ultra-fast EV charger and GaN IMMD were built, and the results confirm the efficacy of the proposed designs. Model predictive control (MPC) is a nonlinear control technique that has been widely investigated for various power electronic applications in the past decade. MPC exploits the discrete nature of power converters to make control decisions using a cost function. The controller offers various advantages over, e.g., linear PI controllers in terms of fast dynamic response, identical performance at a reduced switching frequency, and ease of applicability to MIMO applications. This dissertation also investigates MPC for key power electronic applications, such as, grid-tied VSC with an LCL filter and multilevel VSI with an LC filter. By implementing high performance MPC controllers on WBG based power converters, it is possible to formulate designs capable of fast dynamic tracking, high power operation at reduced THD, and increased power density

A distributed model predictive control strategy for back-to-back converters

In recent years Model Predictive Control (MPC) has been successfully used for the control of power electronics converters with different topologies and for different applications. MPC offers many advantages over more traditional control techniques such as the ability to avoid cascaded control loops, easy inclusion of constraint and fast transient response. On the other hand, the controller computational burden increases exponentially with the system complexity and may result in an unfeasible realization on modern digital control boards. This paper proposes a novel Distributed Model Predictive Control, which is able to achieve the same performance of the classical Model Predictive Control whilst reducing the computational requirements of its implementation. The proposed control approach is tested on a AC/AC converter in a back-to-back configuration used for power flow management. Simulation results are provided and validated through experimental testing in several operating conditions

New configurations of power converters for grid interconnection systems

The increased penetration of renewable energy sources and other distributed energy sources has been seen nowadays. In this scenario power converters play a crucial role by providing the interconnection of these energy sources. This paper presents new configurations of power converters for grid interconnection systems. Several topologies are analyzed which are based on isolated ac-ac matrix converters

Novel DC Capacitor Voltage Balancing Strategy of Modular Multilevel Converter based STATCOM for Reactive Power Compensation and Voltage Improvement

In recent years, the integration of renewable energy sources and their unpredictable nature has posed significant challenges to power grid stability and voltage regulation. To address these issues, the Modular Multilevel Converter (MMC) based Static Synchronous Compensator (Statcom) has emerged as a promising solution for reactive power compensation and voltage improvement. However, one critical concern in MMC-Statcom operation is the voltage balancing of DC capacitors, which directly affects system performance and efficiency. In this research, a novel DC capacitor voltage balancing strategy is proposed for MMC-Statcom to ensure optimal operation and enhanced performance. The proposed strategy employs advanced control algorithms and innovative switching techniques to maintain balanced DC capacitor voltages under varying operating conditions. By achieving balanced capacitor voltages, the MMC-Statcom can effectively compensate reactive power and regulate the grid voltage with improved efficiency and stability. The effectiveness of the proposed DC capacitor voltage balancing strategy is extensively evaluated through simulation studies and experimental validations. Comparative analyses are performed with existing voltage balancing methods, demonstrating superior performance and robustness of the novel strategy. The results showcase its potential for practical implementation in real-world power systems. Overall, this study presents a significant advancement in MMC-Statcom technology, providing an effective solution for reactive power compensation and voltage improvement while ensuring reliable and stable grid operation. The proposed novel DC capacitor voltage balancing strategy holds the promise of contributing to the enhancement of power system stability and facilitating the integration of renewable energy sources in modern electrical grids

Improved Predictive Control in Multi-Modular Matrix Converter for Six-Phase Generation Systems

Distributed generation systems are emerging as a good solution as part of the response to the world’s growing energy demand. In this context multi-phase wind generation systems are a feasible option. These systems consist of renewable AC sources which requires efficient and controlled power conversion stages. This work proposes a novel predictive current control strategy that takes advantage of a multi-modular matrix converter topology in the power stage of a six-phase generation system. The proposed method uses a coupling signal between the modules to decrease the error and the total harmonic distortion compared to independent control of each module. Experimental results validate the new control strategy showing the improvement regarding the target parameters

High-performance motor drives

This article reviews the present state and trends in the development of key parts of controlled induction motor drive systems: converter topologies, modulation methods, as well as control and estimation techniques. Two- and multilevel voltage-source converters, current-source converters, and direct converters are described. The main part of all the produced electric energy is used to feed electric motors, and the conversion of electrical power into mechanical power involves motors ranges from less than 1 W up to several dozen megawatts