System identification of a dc-dc converter system using a fast affine projection algorithm

Many fast affine projection (FAP) algorithms have been proposed in the last two decades. These algorithms offer a good tradeoff between convergence rate and computational complexity. Most of the existing FAP algorithms use a constant projection order. Recently, the evolutionary APA (E-APA) with a variable projection order has been proposed. In this paper, an efficient implementation of the E-APA based on dichotomous coordinate descent (DCD) method is proposed and investigated. It is shown that the proposed algorithm obtains both fast convergence speed and small steady-state error.

In this paper we will present a method to facilitate bachelor students with educational laboratory setups which they can use to build fully operational mechatronic and power electronic systems in the spirit of the internet of things. First we will examine all required components and their position in the overall system. It will be demonstrated that both analog and digital control can be applied to the same power electronics board and that this system can be controlled via a web-server. Starting with the internet connection, a Single Board Computer [SBC] will be able to connect to a web-server running a server-side script for communication with the outside world. The user has access to this web-server and can set parameters. The SBC can control multiple micro-controllers via I2C or USB connections. A micro-controller is then reading signals and giving control signals to a high speed analog control circuitry which in turn can regulate the power electronics. The power electronics regulates the electric motor or actuator, driving the actual applications. The main focus of this paper is on the development of a general power electronics board that facilitates multiple purposes. Several aspects of energy conversion have to be taken into consideration and therefore, the board is made general in such a way, that it can serve as a platform to teach students the variety of DC-DC and DC-AC converters that form the energy conversion backbone in the future IoT.

This paper considers an adaptive echo canceller which can be used in tasks of acoustic or electrical echo cancellation. The solution of these tasks usually requires the usage of the adaptive filters with a large number of weights. This means that a lot of computational resources of hardware or software are required for the echo canceller implementation. The usage of the Fast (computationally efficient) Affine Projection (FAP) adaptive filtering algorithm ensures the adaptive filter functional efficiency and complexity tradeoff in the echo cancellation tasks. The algorithm consists of two groups of calculations: a fast calculation of the adaptive filter error and a fast calculation of the normalizing matrix and its inversion. The second group is based on the usage of some calculations adopted from the sliding window Fast Recursive Least Squares adaptive filtering algorithms. However these calculations are potentially unstable. The given paper presents a simplified stable version of the multichannel FAP algorithm. The simplification is achieved due to the diagonalization of the normalizing matrix that ensures a simple procedure of direct calculation of this matrix and its inversion. If the echo signal is noisy (and that what always happens in our real world) then the original and the simplified FAP algorithms demonstrate about the same performance. The simulation of the two-channel acoustic echo cancellers confirms this statement.

This paper describes the medium voltage high power DVR (dynamic voltage restorer) with the new voltage disturbance detection method and the real-time digital voltage control. The new voltage disturbance detector was implemented by using the delta rule of the neural network control. Through the proposed method, we can instantaneously obtain the peak value of each phase voltage even under the single phase input voltage conditions. Compared to the conventional synchronous reference frame method, the proposed one shows the minimum time delay to determine the instance of the voltage sag or voltage swell event. Also real-time digital voltage control technique was adopted, where the inverter output filter capacitance voltage, the filter reactor current and the load current are sampled to calculate the inverter PWM command for the next sampling interval. By using digital control, the disturbance voltage can be compensated to the reference voltage level within two sampling intervals. The proposed disturbance detector and the voltage compensator were applied to the medium voltage high power DVR (22.9 kV/4 MVA) that was developed for the application of semiconductor manufacture plant. The performances of the proposed DVR control were verified through computer simulation and experimental results. Finally, conclusions are given.

Multi-cell inverter include an array of singlephase inverters capable of handling higher voltage ratings with lower rating power electronics devices. In this paper, a Real Time Digital Feedback Controller (RTDFBC) combined with a Repetitive Controller is proposed to control a Variable Frequency Drive (VFD) fed by a multi-cell inverter. This digital control is characterized by a very fast transient response, low switching losses, and a proper compensation for load disturbances and cyclical fluctuations.

Power electronics are used to minimize losses in converting the energy produced by the generator in a wind turbine, and to drive motors that control the pitch and yaw of the wind turbine to ensure maximum power extraction. The power electronic system is based on a series of three-phase pulse width modulated (PWM) power modules consisting of IGBT power switches and associated diodes that are soldered to a ceramic substrate and interconnected with wirebonds. The design of the packaging and cooling of the power electronics is crucial to enhancing the energy efficiency and the reliability of the electronics, which generate heat loads in the hundreds of watts/cm2, and are often placed in harsh and inaccessible offshore environments. Without adequate heat removal, the increase in device temperature will reduce the efficiency of power electronic devices leading to thermal runaway and eventual failure of the entire power electronic system. Furthermore, the increased temperatures can lead to failure of the packaging elements as well. This paper will provide an overview of the fundamental packaging level mechanisms that can cause failures in the power electronic system. These include wirebond and lead fatigue, die attach fatigue, substrate cracking, and lead bonding fatigue.

Power electronic systems have become a key component in the efficient generation, distribution, storage, and use of energy. This increasingly places power electronic systems in harsh environments under elevated stress conditions where, in many cases, their reliable operation is now mission critical. The semiconductor material conventionally used, silicon, possesses limited capability for high temperature applications due to its small bandgap. Power electronic components based on wide bandgap (WBG) semiconductors, such as SiC and GaN, can be operated reliably at higher temperatures. Furthermore, WBG devices have higher breakdown voltages and switching frequencies, rendering them more ideal switches and rectifiers for highefficiency as well as low-volume and low-weight systems. Yet, new packaging concepts are required to make use of the high temperature capability of power electronic systems based on WBG semiconductor devices. In this paper, a summary of the progress in the development and commercialization of wide bandgap power components and power electronic systems is given. The properties of SiC and GaN components are compared to those based on silicon. The shortcomings of conventional power electronic packaging technologies are analyzed, and alternatives introduced and compared. An overview of research is given on Transient Liquid Phase Sintering (TLPS), a promising interconnect technology for the manufacturing of WBG and high temperature power electronic systems. TLPS is a liquid-assisted sintering process during which a low melting temperature constituent melts, surrounds, and diffuses in a high melting temperature constituent. Intermetallic compounds with high melting temperatures are formed by liquid-solid diffusion. Interconnect systems can be processed at low temperatures but are capable of operating at the high melting temperatures of the intermetallic compound. Different process approaches are contrasted and material systems compared. Latest results of research on paste-based low temperature TLPS are presented. The pastes assessed are based on the Cu-Sn and Ni-Sn material systems. It is shown that joints formed by TLPS remain strong up to 600°C and exhibit softening temperatures far higher than conventional interconnect technologies. They show minimum creep and possess very limited voiding. The process does not require an inert or reducing atmosphere or vacuum and is compatible with standard reflow soldering equipment. It shows good wettability to common metallizations such as Cu, Ni, Ag, and ENIG. This attach technology shows the potential to enable reliable operation of wide bandgap power electronic systems under high stress conditions.

This paper investigates a permanent magnet synchronous generator (PMSG)-based wind energy conversion system (WECS) evaluating various conditions of power flow. The variable parameter reweighted zero-attracting least mean square (VP-RZA-LMS) algorithm is applied to the voltage source inverter (VSI) to account for a variety of power quality problems like compensation of reactive power, power balancing and active power transfer. A Simulink model is developed to validate the same. The proposed control algorithm provides faster convergence speed and is also dependent on a relatively lesser number of parameters.KeywordsWind energy conversion system (WECS)Permanent magnet synchronous generator (PMSG)Power qualityLeast mean square (LMS)Power electronics

In this paper, a joint adaptive algorithm combining normalized least mean square (NLMS) and recursive least squares (RLS) is presented for digital predistortion to compensate nonlinearity of power amplifier (PA). NLMS features stability and less calculation amount, while RLS characterizes precision and fast convergence speed. The simulation results show that this joint method can achieve not only a desirable linearization performance, but the rapid convergence and better stability.Keywordspower amplifierdigital predistortionnormalized least mean Squarerecursive least squares

Power electronics, a pivotal field orchestrating electrical energy flow in the modern world, deals with efficient conversion, control, and management of electrical power across diverse applications. While its scope encompasses circuits for energy conversion, its challenges include transporting electrical energy over extended distances. Focusing on electrical‐to‐electrical conversions, the goal is minimal loss for delivering maximum power. The article explores the intricacies of power electronics, presenting key equations, and concepts. The current global power electronics market witnesses growth, driven by demand for energy‐efficient technologies, renewables integration, and the rise of electric vehicles. Future trends indicate continued growth, driven by renewable energy systems, and electric vehicles. Wide bandgap semiconductors, play a crucial role, with ultra‐wide bandgap semiconductors like diamond emerging as potential disruptors. A comparative analysis of semiconductor properties reveals diamond's unique attributes. Despite its challenges, diamond shows promise for power electronic applications, with ongoing research on components like Schottky diodes. Thermal considerations, substrate limitations, and dislocation challenges are discussed, emphasizing the need for advancements to harness the full potential of diamond in power electronics. Finally, some inputs about the importance of overcoming these challenges for the successful integration of diamond in power electronic systems are given.

Batteries in a fuel cell power system are essential to provide the additional load demands during the sharp load transients. This necessitates a power electronics system, which would control the energy flow between the fuel cell stack, the battery and the load during the transient and in the steady-state. In this paper, a cost-effective and efficient power electronic system is proposed for a fuel cell based hybrid power system based on a distributed power electronics topology. The system includes a hierarchical controlling architecture, in which the master control optimizes the control parameters of the individual subsystem controls, which in turn optimizes the performance and efficiency of the overall system while nullifying the effects of load transients on the fuel cell stack subsystem. The power electronics system concept is further experimentally validated using a four module bidirectional DC-DC converter with Nexa PEM stack.

The tracking/rejection of periodic signals constitutes a wide field of research in the control theory and applications area and Repetitive Control has proven to be an efficient way to face this topic; however, in some applications the period of the signal to be tracked/rejected changes in time or is uncertain, which causes and important performance degradation in the standard repetitive controller. This thesis presents some contributions to the open topic of repetitive control working under varying frequency conditions. These contributions can be organized as follows: One approach that overcomes the problem of working under time varying frequency conditions is the adaptation of the controller sampling period, nevertheless, the system framework changes from Linear Time Invariant to Linear Time-Varying and the closed-loop stability can be compromised. This work presents two different methodologies aimed at analysing the system stability under these conditions. The first one uses a Linear Matrix Inequality (LMI) gridding approach which provides necessary conditions to accomplish a sufficient condition for the closed-loop Bounded Input Bounded Output stability of the system. The second one applies robust control techniques in order to analyse the stability and yields sufficient stability conditions. Both methodologies yield a frequency variation interval for which the system stability can be assured. Although several approaches exist for the stability analysis of general time-varying sampling period controllers few of them allow an integrated controller design which assures closed-loop stability under such conditions. In this thesis two design methodologies are presented, which assure stability of the repetitive control system working under varying sampling period for a given frequency variation interval: a mu-synthesis technique and a pre-compensation strategy. On a second branch, High Order Repetitive Control (HORC) is mainly used to improve the repetitive control performance robustness under disturbance/reference signals with varying or uncertain frequency. Unlike standard repetitive control, the HORC involves a weighted sum of several signal periods. With a proper selection of the associated weights, this high order function offers a characteristic frequency response in which the high gain peaks located at harmonic frequencies are extended to a wider region around the harmonics. Furthermore, the use of an odd-harmonic internal model will make the system more appropriate for applications where signals have only odd-harmonic components, as in power electronics systems. Thus an Odd-harmonic High Order Repetitive Controller suitable for applications involving odd-harmonic type signals with varying/uncertain frequency is presented. The open loop stability of internal models used in HORC and the one presented here is analysed. Additionally, as a consequence of this analysis, an Anti-Windup (AW) scheme for repetitive control is proposed. This AW proposal is based on the idea of having a small steady state tracking error and fast recovery once the system goes out of saturation. The experimental validation of these proposals has been performed in two different applications: the Roto-magnet plant and the active power filter application. The Roto-magnet plant is an experimental didactic plant used as a tool for analysing and understanding the nature of the periodic disturbances, as well as to study the different control techniques used to tackle this problem. This plant has been adopted as experimental test bench for rotational machines. On the other hand, shunt active power filters have been widely used as a way to overcome power quality problems caused by nonlinear and reactive loads. These power electronics devices are designed with the goal of obtaining a power factor close to 1 and achieving current harmonics and reactive power compensation.

A stochastic conjugate gradient multi-modulus algorithm based on global artificial fish swarm and genetic optimization DNA encoding sequences(GAFS-GDNA-SMMA) is proposed to solve the high computational loads, low convergence rate, and large mean square error(MSE) of the multi-modulus blind equalization algorithm(MMA). In this proposed algorithm, the optimal DNA coding sequence can be found and used as the initial optimal weight vector of the stochastic conjugate gradient MMA(SMMA) after decoding the optimization DNA sequences. The simulation results show that the proposed algorithm has the faster convergence speed and smaller mean square error comparison with MMA, SMMA, GA-DNA-SMMA(Genetic algorithm and DNA optimization based SMMA)

Modeling and Verification of Dependable Electronic Power System Architecture

The electronic power system can be viewed as a system composed of a set of concurrently interacting subsystems to generate, transmit, and distribute electric power. The complex interaction among sub-systems makes the design of electronic power system complicated. Furthermore, in order to guarantee the safe generation and distribution of electronic power, the fault tolerant mechanisms are incorporated in the system design to satisfy high reliability requirements. As a result, the incorporation makes the design of such system more complicated. We propose a dependable electronic power system architecture, which can provide a generic framework to guide the development of electronic power system to ease the development complexity. In order to provide common idioms and patterns to the system *designers, we formally model the electronic power system architecture by using the PVS formal language. Based on the PVS model of this system architecture, we formally verify the fault tolerant properties of the system architecture by using the PVS theorem prover, which can guarantee that the system architecture can satisfy high reliability requirements. KeywordsSystem Architecture; PVS System; Fault Tolerance; Formal Modeling; Formal Verification.