Novel single-phase five-level VIENNA-type rectifier with model predictive current control

A novel single-phase five-level active rectifier based on the VIENNA-type rectifier with model predictive current control is presented. The proposed topology operates in unidirectional mode, imposing a sinusoidal grid-side current with unitary power factor. A unidirectional electric vehicle battery charger is the target application in which the proposed rectifier is used; however, it can also be used as an active rectifier for other purposes aiming to improve the efficiency of ac-to-dc rectification. The model predictive current control is used to select the active rectifier state during each sampling period, trying to minimize the grid current error and obtain low total harmonic distortion. The suitability and performance of the proposed topology of active rectifier, as well as the principle of operation and the digital control algorithm, are evaluated through simulation and experimental results.This work has been supported by COMPETE: POCI-01- 0145–FEDER–007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation – COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT – Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015 – POCI – 01–0145–FEDER–016434.info:eu-repo/semantics/publishedVersio

Modelamiento y desarrollo de un rectificador Boost PFC sin puente

RESUMEN: Este artículo propone un modelo para rectificadores elevadores PFC (Power Factor Correction por sus siglas en inglés) sin puente para propósitos de control y basado en el análisis del promedio de pequeña señal. A partir de las leyes circuitales, cuatro modos de operación son definidos y explicados, asegurando una relación entre las variables físicas del convertidor. Basados en el modelo propuesto, dos lazos cerrados de control compuestos por controladores lineales Proporcionales e Integrales (PI) son propuestos. Algunas consideraciones de diseño para dimensionar los elementos reactivos son incluidas, de tal forma que se obtienen valores mínimos para su inductancia y capacitancia. Se presenta la implementación de un prototipo de 900 W con resultados experimentales que permite validar y reafirmar el modelo propuesto. Los resultados experimentales demuestran que el uso del convertidor PFC permite elevar el factor de potencia FP a 0,99 o más y reducir el THDi (Total Harmonic Distortion of the Current por sus siglas en Inglés) a 3,9 %, además de controlar el bus DC en la salida. Se verifica experimentalmente que el convertidor PFC desarrollado está de acuerdo con los estándares de calidad de la potencia EN 61000-3-2 (IEC 1000-3-2).ABSTRACT: This paper proposes a model of the bridgeless PFC (Power Factor Correction) boost rectifier for control purposes based on an averaged small-signal analysis. From circuital laws, four operation modes are defined and explained, ensuring a relationship of physical variables in the converter. Based on the proposed model, two-loop cascade control structures composed of Proportional-Integral (PI) lineal controllers are proposed. Design consideration for dimensioning reactive elements is included, providing minimum values for their inductance and capacitance. Implementation of a laboratory prototype of 900 W and experimental results are presented to validate and reaffirm the proposed model. Experimental results demonstrate that the use of the bridgeless PFC boost converter model allows the Power Factor (PF) to be elevated up to 0.99, to reduce the THDi (Total Harmonic Distortion of the Current) to 3.9% and to control the DC voltage level on output. Compliance of standards of power quality EN 61000-3-2 (IEC 1000-3-2) are experimentally verified

Experimental validation of a proposed single-phase five-level active rectifier operating with model predictive current control

This paper presents a model predictive current control applied to a proposed single-phase five-level active rectifier (FLAR). This current control strategy uses the discrete-time nature of the active rectifier to define its state in each sampling interval. Although the switching frequency is not constant, this current control strategy allows to follow the reference with low total harmonic distortion (THDF). The implementation of the active rectifier that was used to obtain the experimental results is described in detail along the paper, presenting the circuit topology, the principle of operation, the power theory, and the current control strategy. The experimental results confirm the robustness and good performance (with low current THDF and controlled output voltage) of the proposed single-phase FLAR operating with model predictive current control.This work has been supported by FCT – Fundação para a Ciência e Tecnologia in the scope of the project: PEstUID/CEC/00319/2013. Mr. Vítor Monteiro was supported by the doctoral scholarship SFRH/BD/80155/2011 granted by the FCT agency

Model predictive control applied to an improved five-level bidirectional converter

This paper presents an improved five level bidirectional converter (iFBC) controlled by finite control set model predictive control (FCS-MPC). This control strategy consists in using the discrete time nature of the iFBC to define its state in each sampling interval. Using FCS-MPC the switching frequency is not constant; however, it is suitable to follow the current reference with low total harmonic distortion (THD). The iFBC prototype that was specially developed for obtaining experimental results is described in detail along the paper, as well as its principle of operation, power theory, and current control strategy. The iFBC was experimentally validated connected to the power grid through a second order LfCf passive filter, operating as an active rectifier and as a grid tie inverter. For both operation modes, the experimental results confirm the good performance (in terms of efficiency, low current THD and controlled output voltage) of the iFBC controlled by FCS-MPC.FC

Data Center Power System Emulation and GaN-Based High-Efficiency Rectifier with Reactive Power Regulation

Data centers are indispensable for today\u27s computing and networking society, which has a considerable power consumption and significant impact on power system. Meanwhile, the average energy usage efficiency of data centers is still not high, leading to significant power loss and system cost. In this dissertation, effective methods are proposed to investigate the data center load characteristics, improve data center power usage efficiency, and reduce the system cost. First, a dynamic power model of a typical data center ac power system is proposed, which is complete and able to predict the data center\u27s dynamic performance. Also, a converter-based data center power emulator serving as an all-in-one load is developed. The power emulator has been verified experimentally in a regional network in the HTB. Dynamic performances during voltage sag events and server load variations are emulated and discussed. Then, a gallium nitride (GaN) based critical conduction mode (CRM) totem-pole power factor correction (PFC) rectifier is designed as the single-phase front-end rectifier to improve the data center power distribution efficiency. Zero voltage switching (ZVS) modulation with ZVS time margin is developed, and a digital variable ON-time control is employed. A hardware prototype of the PFC rectifier is built and demonstrated with high efficiency. To achieve low input current total harmonic distortion (iTHD), current distortion mechanisms are analyzed, and effective solutions for mitigating current distortion are proposed and validated with experiments. The idea of providing reactive power compensation with the rack-level GaN-based front-end rectifiers is proposed for data centers to reduce data center\u27s power loss and system cost. Full-range ZVS modulation is extended into non-unity PF condition and a GaN-based T-type totem-pole rectifier with reactive power control is proposed. A hardware prototype of the proposed rectifier is built and demonstrated experimentally with high power efficiency and flexible reactive power regulation. Experimental emulation of the whole data center system also validates the capability of reactive power compensation by the front-end rectifiers, which can also generate or consume more reactive power to achieve flexible PF regulation and help support the power system

A novel control strategy based on predictive control for a bidirectional interleaved three-phase converter

An experimental confirmation of predictive control applied to a bidirectional interleaved three-phase (BIT) converter is presented. The BIT converter is a powerful solution for numerous applications, mainly, renewables interface, motor drivers, active rectifiers, and active power filters. However, a precise and robust digital control strategy is required, maintaining a low computational effort. In this paper, a predictive control based on continuous control set is proposed as a new control scheme for the BIT converter, permitting the control of the ac side current with fixed switching frequency and with a faster response. The predictive control scheme applied to the BIT converter is defined along the paper, evidencing in detail the digital employment aspects according to the discrete-time model of the BIT converter. An explicit experimental validation under realistic operating conditions is presented using a developed laboratorial prototype, highlighting the convenience of the control applied to the BIT converter.This work has been supported by FCT – Fundação para a Ciência e Tecnologia in the scope of the project: PEstUID/CEC/00319/2013. This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation < COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT < Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015< POCI< 01<0145<FEDER<016434. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency.info:eu-repo/semantics/publishedVersio

Power factor correction without current sensor based on digital current rebuilding

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 works. F. J. Azcondo, Á. de Castro, V. M. López, Ó. García, "Power Factor Correction Without Current Sensor Based on Digital Current Rebuilding", IEEE Transactions on Power Electronics, vol. 25, no. 6, pp. 1527 - 1536, June 2010.A new digital control technique for power factor (PF) correction is presented. The main novelty of the method is that there is no current sensor. Instead, the input current is digitally rebuilt, using the estimated input current in the current loop. The circuit measures the input and output voltage by means of low cost ad hoc analog-to-digital converters (ADCs). Taking advantage of the slow dynamic behavior of these voltages, almost completely digital ADCs have been designed, leaving only a comparator and an RC filter in the analog part. Avoiding measuring current can provide a significant advantage compared to analog controllers and this also helps to reduce the total cost. The ultimate objective is to obtain a low-cost digital controller that can be easily integrated as an intellectual property (IP) block into a field-programmable gate array, or an application-specific integrated circuit. The experimental results show a reasonably high PF, despite not measuring the input current, and therefore the feasibility of the method.This work has been funded by the Spanish Government with the project TEC2008-01753 entitled: “Digital power processing for the control of gaseous discharges”

A Single-phase Rectifier With Ripple-power Decoupling and Application to LED Lighting

In recent years, Light-Emitting-Diode (LED) is widely used in lighting applications for its high efficacy and high reliability. However, the rectifier, which is required by the LEDs to convert the AC power from the grid into DC power, suffers from low-reliability caused by the filtering capacitor. In order to fully utilize the long operational hours of the LEDs, this thesis proposes a rectifier that has improved reliability by adding a ripple-port to eliminate the non-reliable electrolytic capacitor. The ripple-port is capable of decoupling the ripple-power inherited in a single-phase rectifier, which enables using the reliable film capacitor to replace the electrolytic capacitor. To guarantee that the ripple-port can effectively decouple the ripple-power, a closed-loop control scheme is designed and implemented in a digital controller. Simulation and experimental results show that the proposed rectifier can reduce the required capacitance by 70%, which results in a 60% increase in lifetime. The proposed ripple-port circuit can be considered as an add-on module to be integrated into the rectifiers used in applications that require long lifetime. A detailed analysis of the efficiency, cost and reliability of applying the ripple-port in LED lighting applications supports the feasibility of the proposed circuit

Hardware implementation of boost power factor correction converter.

Nowadays, there has been an increasing demand of unity power factor in electrical power sector. Due to the nonlinear nature of load equipment, switching devices, source voltage and current are out of phase with each other. Many power converters topologies are used for the power factor correction. The boost converter with controller is most common for power factor correction circuits. The controller objective is to maintain the output voltage regulation and input current tracking with source voltage. The voltage ripple present due to the ac component of the current tracking objective, hence instead of ignoring that ripple, it is used in controller designing. The mathematical modeling of system depends on ac and dc dynamics of the circuit. The Lypunov stability analysis used for designing the controller of boost converter. In this work, experimental set-up for boost power factor correction converter was made with power pole board and NI compact RIO. The controller algorithm executed in LabVIEW FPGA module and results were verified. This novel controller ensures the convergence of the error signal by stability analysis