Decoupled DC-Link capacitor voltage control of DC-AC multilevel multileg converters

© 2015 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 worksThis paper studies the coupling between the capacitor voltage control loops of diode-clamped (or functionally equivalent) multilevel multileg (multiphase) dc-ac converters. From a complete model of the plant revealing the coupling, a simple approach consisting in multiplying the vector of control commands by a constant matrix is proposed to decouple the control problem and achieve a better controller performance. Simulation and experimental results are presented to prove the superior performance of the proposed decoupled control.Postprint (author's final draft

Multibattery charger system based on a three-level dual-active-bridge power converter

© 2021 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 works.A charger for two batteries connected in series is presented in this work. From the three-phase grid, the batteries are charged through a three-level neutral-point-clamped ac-dc converter in cascade with a three-level dual active bridge converter. The system provides galvanic isolation and allows bidirectional power flow. A simple control strategy to charge the batteries is presented, based on the regulation of the commonand differential-mode components of the batteries’ charging currents. With this control approach, each battery bank can be charged independently, allowing it to reach full battery bank capacity, even under different battery initial state-of-charge values or different battery nominal capacities. Moreover, the proposed control system also regulates the total dc-link voltage and the dc-link voltage balance in both dc-links of the system. The simulation results verify the feasibility of the proposed implementation and control system approach.This work was supported by the Ministerio de Economía, Competitividad, Spain, under Grant DPI2017-89153-P (AEI/FEDER, UE).Peer ReviewedPostprint (published version

Comparison of modulations and dc-link balance control strategies for a multibattery charger system based on a three-level dual-active-bridge power converter,

© 2022 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 works.This paper focuses on the study of a charger for two batteries connected in series. From the three-phase grid, the batteries are charged through a three-level neutral-point-clamped (NPC) ac-dc converter in cascade with a three-level NPC dualactive-bridge converter. The system provides galvanic isolation and allows bidirectional power flow. A simple control strategy to charge the batteries is considered, based on the regulation of the common- and differential-mode components of the batteries charging currents. In addition, the proposed control system regulates the total dc-link voltage and the dc-link voltage balance in the two systems dc-links. This work is particularly focused on the comparison of the charger performance under two competitive ac-dc converter modulations, in terms of the ac-side voltage harmonic content, the number of switching transitions, the dc-link voltage balance, and the charging current control capacity. Simulation results with the performance comparison are provided and the merits and demerits of each option are highlighted.This publication is part of Grant DPI2017-89153-P, funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe.Peer ReviewedPostprint (author's final draft

Switching-Cell Arrays - An Alternative Design Approach in Power Conversion

© 2018 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 conventional design of voltage-source power converters is based on a two-level half-bridge configuration and the selection of power devices designed to meet the full application specifications (voltage, current, etc.). This leads to the need to design and optimize a large number of different devices and their ancillary circuitry and prevents taking advantage from scale economies. This paper proposes a paradigm shift in the design of power converters through the use of a novel configurable device consisting on a matrix arrangement of highly-optimized switching cells at a single voltage class. Each switching cell consists of a controlled switch with antiparallel diode together with a self-powered gate driver. By properly interconnecting the switching cells, the switching cell array (SCA) can be configured as a multilevel active-clamped leg with different number of levels. Thus, the SCA presents adjustable voltage and current ratings, according to the selected configuration. For maximum compactness, the SCA can be conceived to be only configurable by the device manufacturer upon the customer needs. For minimum cost, it can also be conceived to be configurable by the customer, leading to field-configurable SCAs. Experimental results of a 6x3 field-configurable SCA are provided to illustrate and validate this design approach.Peer ReviewedPostprint (author's final draft

Enhanced DC-Link Capacitor Voltage Balancing Control of DC-AC Multilevel Multileg Converters

This paper presents a capacitor voltage balancing control applicable to any multilevel dc-ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc-ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five-phase dc-ac conversion system

Enhanced DC-Link Capacitor Voltage Balancing Control of DC-AC Multilevel Multileg Converters

This paper presents a capacitor voltage balancing control applicable to any multilevel dc-ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc-ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five-phase dc-ac conversion system.Postprint (published version