A RISC-V Vector Processor With Simultaneous-Switching Switched-Capacitor DC-DC Converters in 28 nm FDSOI

This work demonstrates a RISC-V vector microprocessor implemented in 28 nm FDSOI with fully integrated simultaneous-switching switched-capacitor DC-DC (SC DC-DC) converters and adaptive clocking that generates four on-chip voltages between 0.45 and 1 V using only 1.0 V core and 1.8 V IO voltage inputs. The converters achieve high efficiency at the system level by switching simultaneously to avoid charge-sharing losses and by using an adaptive clock to maximize performance for the resulting voltage ripple. Details about the implementation of the DC-DC switches, DC-DC controller, and adaptive clock are provided, and the sources of conversion loss are analyzed based on measured results. This system pushes the capabilities of dynamic voltage scaling by enabling fast transitions (20 ns), simple packaging (no off-chip passives), low area overhead (16%), high conversion efficiency (80%-86%), and high energy efficiency (26.2 DP GFLOPS/W) for mobile devices

Effect of State Feedback Coupling on the Design of Voltage Source Inverters for Standalone Applications

This Ph.D. thesis aims at investigating the effect of state feedback cross‐coupling decoupling of the capacitor voltage on the dynamics performance of Voltage Source Inverters for standalone microgrids/Uninterruptible Power Supply systems. Computation and PWM delays are the main factors which limit the achievable bandwidth of current regulators in digital implementations. In particular, the performance of state feedback decoupling is degraded because of these delays. Two decoupling techniques aimed at improving the transient response of voltage and current regulators are investigated, named nonideal and ideal capacitor voltage decoupling respectively. In particular, the latter solution consists in leading the capacitor voltage on the state feedback decoupling path in order to compensate for system delays. Practical implementation issues are discussed with reference to both the decoupling techniques. Moreover, different resonant regulators structures for the inner current loop are analysed and compared to investigate which is the most suitable for standalone microgrid applications. A design methodology for the voltage loop, which considers the closed loop transfer functions developed for the inner current loop, is also provided. Proportional resonant voltage controllers tuned at specific harmonic frequencies are designed according to the Nyquist criterion taking into account application requirements. For this purpose, a mathematical expression based on root locus analysis is proposed to find the minimum value of the resonant gain at the fundamental frequency. The exact model of the output LC filter of a three‐phase inverter is derived in the z‐domain. The devised formulation allows the comparison of two techniques based on a lead compensator and Smith predictor structure. These solutions permit the bandwidth of the current regulator to be widened while still achieving good dynamic performance. As a consequence, the voltage regulator can be designed for a wide bandwidth and even mitigates odd harmonics arising with unbalance loads supply. Discrete‐time domain implementation issues of an anti‐wind up scheme are discussed as well, highlighting the limitations of some discretization methods. Experimental tests performed in accordance to Uninterruptible Power Supply standards verify the theoretical analysis

New hybrid active power filter for harmonic current suppression and reactive power compensation

In the case of undistorted and balanced grid voltages, low ratio shunt Active Power Filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic-current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt active power filter. A new method for alleviating the negative effects of a non-ideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance results of the proposed HAPF system is tested and presented under non-ideal supply voltage conditions

Single-phase power line conditioning with unity power factor under distorted utility voltage

The paper proposes a control method of a single-phase active power line conditioner (APLC) aimed at correcting the power factor of linear and non-linear loads supplied by distorted voltage utility. The method, that is based on the single-phase p-q theory and utilizes a third-order sinusoidal signal integrator, gets utility unity power factor and, at the same time, overcomes the shortcomings of the solutions pursuing utility sinusoidal current, namely the possible onset of un-damped resonance phenomena and the reduction in the energy delivery capabilities; moreover, the method makes the power factor correction robust against the supply distortion. The excellent performance of the method is substantiated by testing it by means of a hardware-in-the-loop setup

POPRAWA DYNAMIKI PRZEKSZTAŁTNIKOWEGO GENERATORA PV PODCZAS ZRZUTU MOCY

In distribution power grids supplied by dispersed power sources, for example RES (Renewable Energy Sources), in the event of a load dump, unexpected transient states may appear. These states involve a dangerous increase in voltage or current. This situation may lead to the disconnection of these sources. To prevent this phenomenon, a non-linear anti-windup regulator with a conditional integrator has been proposed. This solution allows a significant improvement of the generator’s dynamic properties both at load dump and on return to full load.W sieciach dystrybucyjnych o rozproszonym charakterze zasilania, np. OZE (Odnawialne Źródła Energii), w przypadku wystąpienia zrzutów mocy mogą pojawić się nieoczekiwane stany nieustalone. Polegają one na niebezpiecznym wzroście napięcia lub prądu. Taka sytuacja może doprowadzić do wyłączenia tych źródeł energii. Aby temu zapobiec, zaproponowano nieliniowy regulator anti-windup z warunkowym integratorem. Rozwiązanie to pozwoliło zdecydowanie poprawić własności dynamiczne zarówno przy zrzucie mocy jak i powrocie do pełnego obciążenia

Control Design of a Single-Phase DC/AC Inverter for PV Applications

This thesis presents controller designs of a 2 kVA single-phase inverter for photovoltaic (PV) applications. The demand for better controller designs is constantly rising as the renewable energy market continues to rapidly grow. Some background research has been done on solar energy, PV inverter configurations, inverter control design, and hardware component selection. Controllers are designed both for stand-alone and grid-connected modes of operation. For stand-alone inverter control, the outer control loop regulates the filter capacitor voltage. Combining the synchronous frame outer control loop with the capacitor current feedback inner control loop, the system can achieve both zero steady-state error and better step load performance. For grid-tied inverter control, proportional capacitor current feedback is used. This achieves the active damping needed to suppress the LCL filter resonance problem. The outer loop regulates the inverter output current flowing into the grid with a proportional resonant controller and harmonic compensators. With a revised grid synchronization unit, the active power and reactive power can be decoupled and controlled separately through a serial communication based user interface. To validate the designed controllers, a scaled down prototype is constructed and tested with a digital signal processor (DSP) TMS320F28335

Enabling grid-feeding converters with a dissonant-resonant controller for negative-sequence voltage elimination

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThe mitigation of the adverse effects of voltage unbalance in equipment and power quality can be performed by the power electronic converters that interface distributed generators to the grid. Inspired in a resonant controller, this article presents a dissonant-resonant controller for negative-sequence voltage elimination for a grid-feeding converter connected to the grid. The controller eliminates the negative-sequence voltage at the converter output with a regulable precision, it does not require knowing the grid impedance for successful operation, and it can be a good candidate for parallel operation because it operates not like an integrator, but like an “untuned” integrator. Using the stationary aß frame, a closed-loop model is developed in a complex space vector built from the complexification of the stationary components. This allows extracting stability conditions for safe closed-loop operation as well as deriving design guidelines for the controller parameters. Numerical and experimental results show the ability of the proposed controller to meet its design goals, thus, corroborating the theoretical approachPeer ReviewedPostprint (author's final draft

A generalized switching function-based SVM algorithm of single-phase three-leg converter with active power decoupling

In this paper, a generalized switching function-based space vector modulation (SVM) algorithm is presented and evaluated to minimize the dc voltage utilization and the ac utility grid current total harmonic distortion. This paper explores the control and modulation techniques of a single-phase three-leg converter with an active power decoupling method, where a generalized SVM algorithm is proposed and evaluated for easy implementation in a digital control platform. The active power decoupling method with the proposed converter can be achieved via dependent control and modulation techniques. The control method is separated into the ac active power control part and the dc power ripple control part, which can maintain a unity power factor at the ac utility grid and reduced the double-frequency ripple power effect on the dc-side. Simulation results validate the performance of the modulation algorithm and its control and demonstrate the feasibility of the proposed power converter, as well as the two mentioned operation modes of the power converter

Evaluation of a Trapezoidal Predictive Controller for a Four-Wire Active Power Filter for Utility Equipment of Metro Railway, Power-Land Substations

The realization of an improved predictive current controller based on a trapezoidal model is described, and the impact of this technique is assessed on the performance of a 2 kW, 21.6 kHz, four-wire, Active Power Filter for utility equipment of Metro Railway, Power-Land Substations. The operation of the trapezoidal predictive current controller is contrasted with that of a typical predictive control technique, based on a single Euler approximation, which has demonstrated generation of high-quality line currents, each using a 400 V DC link to improve the power quality of an unbalanced nonlinear load of Metro Railway. The results show that the supply current waveforms become virtually sinusoidal waves, reducing the current ripple by 50% and improving its power factor from 0.8 to 0.989 when the active filter is operated with a 1.6 kW load. The principle of operation of the trapezoidal predictive controller is analysed together with a description of its practical development, showing experimental results obtained with a 2 kW prototype

A Comprehensive Survey on Different Control Strategies and Applications of Active Power Filters for Power Quality Improvement

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Power quality (PQ) has become an important topic in today’s power system scenario. PQ issues are raised not only in normal three-phase systems but also with the incorporation of different distributed generations (DGs), including renewable energy sources, storage systems, and other systems like diesel generators, fuel cells, etc. The prevalence of these issues comes from the non-linear features and rapid changing of power electronics devices, such as switch-mode converters for adjustable speed drives and diode or thyristor rectifiers. The wide use of these fast switching devices in the utility system leads to an increase in disturbances associated with harmonics and reactive power. The occurrence of PQ disturbances in turn creates several unwanted effects on the utility system. Therefore, many researchers are working on the enhancement of PQ using different custom power devices (CPDs). In this work, the authors highlight the significance of the PQ in the utility network, its effect, and its solution, using different CPDs, such as passive, active, and hybrid filters. Further, the authors point out several compensation strategies, including reference signal generation and gating signal strategies. In addition, this paper also presents the role of the active power filter (APF) in different DG systems. Some technical and economic considerations and future developments are also discussed in this literature. For easy reference, a volume of journals of more than 140 publications on this particular subject is reported. The effectiveness of this research work will boost researchers’ ability to select proper control methodology and compensation strategy for various applications of APFs for improving PQ.publishedVersio