Search query: flying capacitor medium voltage

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abstract: With the commercialization of wide bandgap (WBG) semiconductor devices, the design strategy of medium voltage inverters has to change. This paper compares SiC MOSFET in two medium voltage multilevel inverters: Flying Capacitor Converter (FCC) and Modular Multilevel Converter (MMC) Both topologies have a single DC source and floating capacitors. Capacitor selection and power loss analysis are compared and the simulation results of both topologies are presented. The result shows that FCC is superior in terms of power density because the capacitor size of the FCC is directly related to the switching frequency whereas the capacitor size of the MMC is related to AC line frequency. FCC also has fewer switching devices and capacitors, and better utilization of switching devices. On the other hand, the MMC has better modularity, lower capacitor current, lower total harmonic distortion (THD) and a more mature voltage balance strategy. The efficiency of both topologies is comparable.
author_names: Daxin Jiao

Qingyun Huang

Alex Q Huang
title: Evaluation of Medium Voltage SiC Flying Capacitor Converter and Modular Multilevel Converter
venue: 2020 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2020

abstract: This paper presents a medium voltage (1.5 kV) flying capacitor DC/DC converter rated at 30 kW. The fast switching 1.2 kV/11 mO SiC MOSFETs converter operates in quasi 2 level (Q2L) mode at high frequency (100 kHz) to obtain a low size of the flying capacitor (330 nF) Moreover, a novel switching pattern is introduced and ZVS at turn on is also enabled. Such control method leads to lower switching losses, higher switching frequency and minimized inductor volume compared to more conventional topologies. Presented experimental results prove correct operation of the proposed converter and control method.
author_names: Rafal Kopacz

Przemyslaw Trochimiuk

Grzegorz Wrona

Jacek Rabkowski
title: High Frequency SiC Based Medium Voltage Quasi 2 Level Flying Capacitor DC/DC Converter With Zero Voltage Switching
venue: 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)
year: 2020

abstract: Medium voltage converters are becoming more relevant in future grid applications. Especially more wind and PV generation systems will be have to added and integrated into the grid in order to achieve the required reduction in CO2 emissions. High power generation units will be integrated into the grid at medium voltage level. Furthermore meshed MV grids will require interties based on MV converter technology. Today's standard medium voltage converters are either based on the MMC technology or us 3L/5L approaches operated at low switching frequencies and containing bulky filters. Both concepts still lead to relatively high costs and low efficiencies which are major reasons for the slow spread of power converters in medium voltage grid applications. Future grid applications demand less distortion, higher reliability and lower costs for converter systems at each voltage level. The Quasi Two Level operation of the flying capacitor multilevel converter with silicone carbide (SiC) based semiconductors is a method for achieving these requirements for medium voltage converters. This paper presents a new concept for minimizing capacitance and balancing the capacitors with fast switching semiconductors. Moreover, a novel approach for limiting the overvoltage stress caused by the Quasi Two Level modulation of a flying capacitor converter is presented.
author_names: Stefan Mersche

Daniel Bernet

Marc Hiller
title: Quasi Two Level Flying Capacitor Converter for Medium Voltage Grid Applications
venue: 2019 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2019

abstract: This paper proposes the coupled inductor instead of four noncoupled inductors in each leg of the flying capacitor modular multilevel converter (MMC) to reduce the dimension, weight and cost of the magnetic core. The simulation results have verified the effectiveness of the proposed coupled inductor.
author_names: Duc Dung Le

Dong-Choon Lee
title: Flying Capacitor Modular Multilevel Converters with Coupled Inductors for Medium Voltage Motor Drive System
year: 2019

abstract: This paper presents a flying capacitor modular multilevel converter (FC MMC) based on series connected submodules. It is intended for completely improving the performance of a medium voltage motor drive system in the entire speed range especially at zero/low speed under rated torque condition. The proposed FC MMC circuit is characterized by the cross connection of upper and lower arm middle taps through a flying capacitor in per phase leg. By properly controlling the ac current flowing through the flying capacitor, the power balance between upper and lower arms is achieved, leading to very small voltage ripples on submodule dc capacitors in the entire speed range from standstill to rated speed even under the rated torque condition. Meanwhile, no common mode voltage is injected. Simulation results obtained from a 4160 V 1 MW model show that the proposed FC MMC along with the proposed control method performances satisfactorily in dynamic and static state even when operated at zero/low speed. Experiments on a downscaled prototype also prove the effectiveness of the proposal.
author_names: Sixing Du

Bin Wu

Navid Reza Zargari

Zhongyuan Cheng
title: A Flying Capacitor Modular Multilevel Converter for Medium Voltage Motor Drive
venue: IEEE Transactions on Power Electronics
year: 2017

author_names: Jaison Mathew
title: Investigation On Dodecagonal Multilevel Voltage Space Vector Structures By Cascading Flying Capacitor And Floating H Bridge Cells For Medium Voltage IM Drives
year: 2017

author_names: Sofia Krogerus
title: Design and analysis of a hysteresis based controller for a flying capacitor active output filter with specific application to medium voltage drives.
year: 2016

abstract: Nowadays, integration of intermittent and distributed renewable energy generations into power grid causes to have power quality problems as concern. These problems are usually causing very costly consequences such as production line and/or sensitive load interruption. Hence, it is crucial to have stable voltage with good quality. One of the most effective power electronics based approach to alleviate the mentioned problems is dynamic voltage restorer (DVR) DVR is capable to restore the voltage at load side whenever grid voltage is disturbed. This paper presents a DVR structure for medium voltage power grid based on double flying capacitor multicell inverter. In the proposed DVR circuit, an energy storage connected to the dc link of the inverter provides the needed active power to restore the voltage quality. In order to minimize the required energy from energy storage, the energy optimized strategy is implemented to compensate the voltage sag. Furthermore, d q synchronous reference frame based method is implemented to calculate the DVR reference voltages. To validate the operation of the presented DVR circuit, simulation results are provided for different cases.
author_names: Arash Khoshkbar-Sadigh

Saleh Farzamkia

Vahid Dargahi
title: Dynamic Voltage Restorer Controlled with Energy Minimized Compensation Method Based on Double Flying Capacitor Multicell Inverter
venue: 2020 Clemson University Power Systems Conference (PSC)
year: 2020

abstract: A Space Vector Pulse Width Modulation (SVPWM) control strategy is implemented for capacitor voltage balancing of Flying Capacitor (FC) based 4 level Neutral Point Clamped (NPC) inverter. This flying capacitor based 4 level NPC inverter is developed for medium voltage and high power applications. This system includes 6 power switching devices, 2 clamping diodes and 2 flying capacitors per leg. The flying capacitors ensure to operate inverter normally and all the switching devices share the voltage stresses in identical manner. Also it controls the voltage across each capacitor and maintained at Vdc/3 times of applied dc voltage. The proposed SVPWM method takes advantage of utilizing redundancy switching states to control and balance the voltage across the capacitor using nearest switching state vector selection method. Moreover, this system provides reduced total harmonic distortion (THD) and minimized voltage stress. The control technique is implemented without using any look up tables or effective logic tables or trigonometric functions. The simulation and experimental results of this proposed verified are verified using Matlab simulink and FPGA controller respectively.
author_names: Rajan Palanisamy

Venkatrama Shanmugasundaram

S Vidyasagar

Vishwa Kalyanasundaram

Krishnasamy Vijayakumar
title: A SVPWM Control Strategy for Capacitor Voltage Balancing of Flying Capacitor Based 4 Level NPC Inverter
year: 2020

abstract: This paper presents three phase four level FLC based electric motor drive for mining application supplied directly from a 6 kV ac grid. It describes complete control algorithms of the drive with active voltage balancing control. The proposed control is verified by experiments carried out on down scale drive prototype of rated power of 35 kVA.
author_names: Dusan Janik

Tomas Kosan

Vojtech Blahnik

Petr Kamenicky

Zdenek Peroutka

Michal Danek
title: Complete solution of 4 level flying capacitor converter for medium voltage drives with active voltage balancing control with phase disposition PWM
venue: 2014 16th European Conference on Power Electronics and Applications
year: 2014