EPE Association: EPE 2023 - DS1d: Modular Multilevel Converters

EPE 2023 - DS1d: Modular Multilevel Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2023 ECCE Europe - Conference > EPE 2023 - Topic 02: Power Converter Topologies and Design > EPE 2023 - DS1d: Modular Multilevel Converters

   [return to parent folder]

   A Multilevel DC-Link Converter for VSC-HVDC Application
By Biao ZHAO, Ruihang BAI, Xueyin ZHANG, Yushuo CHEN, Zhanqing YU, Qiang SONG, Rong ZENG [View]
[Download]

Abstract: This paper proposes a novel topology of AC-DC converter with multilevel DC-link. Sub-valves are connected in series to generate a DC voltage with interleaved superimposition. Each sub-valve includes both a switched-capacitor chain to generate modulation waveform and a H-bridge to half-flip the wave. Modular-designed units help to realize the voltage sharing as well as the floating supply of IGBTs. Its mathematical model is analyzed in detail. Then the voltage regulation method and optimal operating point is given. Finally, the feasibility is verified by simulation. Compared with MMC, the arm capacitance and IGBT devices in MDC are reduced 86\% and 14.8\% respectively. It has significant technical economy and prospect in VSC-HVDC application.

   An Improved Reduced Parallel Modular Multilevel Converter with Sensorless Capacitor Voltage Balancing
By Mostafa ABARZADEH, Masoud AFSHARI, Simon CARON, Saeed PEYGHAMI, Kamal AL-HADDAD [View]
[Download]

Abstract: A new improved reduced parallel modular multilevel converter (RP-MMC) and its generalized topology are proposed in this paper. First, a basic four-level dc cell as well as its improved switching pattern to achieve sensorless voltage balancing of the capacitors is proposed. Then, a seven-level inverter is obtained by applying a low-frequency H-bridge to the proposed four-level dc cell. In addition, generalized topology of the proposed reduced multilevel dc cell is presented and described.Moreover, a new sensorless modified nearest level control (MNLC) switching pattern is proposed for the RP-MMC. The presented experimental results verify the feasibility and viability of the proposed seven-level inverter as well as the proposed MNLC modulation technique.

   Energy based and non-energy based control strategies for Modular Multilevel Converter with embedded storage
By Hind BEKKOURI, Abdelkrim BENCHAIB, Florent MOREL, Pierre RAULT, Juan-Carlos GONZALEZ, Florian ERRIGO [View]
[Download]

Abstract: This paper deals with a high voltage direct current (HVDC) system based on modular multilevel converter (MMC) with embedded energy storage capacity. The dynamic behavior of energy-based (EBC) and non-energy-based (NEBC) controls is analyzed and compared for balanced and unbalanced energy storage distribution. EMTP simulations results show an equivalent performance for both controls when energy storage is balanced. While the NEBC control highlights limitations for unbalanced energy storage management, the EBC shows satisfactory overall performance.

   Enhanced Efficiency of MV Hybrid MMC under Extended Modulation using Si/SiC devices
By Rajat SHAHANE, Poornachandra Rao NALLAMATTI, Anshuman SHUKLA [View]
[Download]

Abstract: The hybrid modular multilevel converter (MMC) consist of series connected half-bridge submodules (HBSMs) and full-bridge submodules (FBSMs) in each arms. The benefits of dc fault blocking and better dc link utilization in hybrid MMC have make them prominent choice for various medium voltage (MV) applications. However, with reduced SM count in MV hybrid MMC still requires additional filter due to the lower number of levels in the output voltage. This require larger filter which increases overall size and deteriorates the converter power density. The use of silicon carbide (SiC) MOSFETs over silicon (Si) IGBT allows high switching frequency operation which leads to reduced filter size, but increases overall cost. In this paper, a hybrid MMC is developed with Si/SiC based FBSM and Si based HBSM. Also, a novel modulation scheme is proposed which allocates all the high frequency function to the SiC devices while the Si devices are switched at relatively lower frequency. Further, simulation study and comparative loss analysis is carried out to prove the efficacy of the proposed system.

   Hybrid Implementation of Cascade Control for GaN-Based Modular Multilevel Converter for Low-Voltage Grid
By Philip KIEHNLE, Niklas KATZENBURG, Lukas STEFANSKI, Marc HILLER [View]
[Download]

Abstract: A hybrid control system implementation for a Modular Multilevel Converter (MMC) prototype is presented in this paper. The cascade control using an ARM processor for the energy controller and a field programmable gate array (FPGA) for the current controllers, allows the GaN semiconductors to generate an output current with an effective ripple frequency of 200 kHz. The MMC system model and the partitioning of the cascade control are shown. With its dynamic current limit, implemented in the FPGA, the MMC is able to provide AC currents above the nominal current. Finally, prototype measurements of an emulated grid fault are shown.

   Impact of pole-to-pole dc voltage on energy requirement of FB YY-MMC
By Sohrab MOHTAT, Massimo BONGIORNO, Mebtu BEZA, Jan R. SVENSSON [View]
[Download]

Abstract: The aim of this paper is to investigate the impact of pole-to-pole DC voltage on the energy requirements of a modular multilevel converter with full-bridge submodules (FB-MMC). With focus on energy-storage equipped FB-MMCs, the relation between the pole-to-pole voltage and the peak-to-peak energy variations in the MMC's arms is derived. Unlike MMC with half-bridge (HB) submodules (SM), in a FB-MMC the pole-to- pole DC voltage can be selected independently of the AC voltage; this allows for reduced energy requirements as well as lower number of FB SMs and capacitors for the same converter ratings. Furthermore, the impact of the converter's circulating current on the MMC's energy requirements is investigated. A guideline for the converter design is provided. Theoretical findings are validated via time-domain simulations.

   Implementation of Active Damping Control Methodology on Modular Multilevel Converter(MMC)-Based Arbitrary Wave Shape Generator Used for High Voltage Testing
By Xiaochuan ZHOU, Dhanashree Ashok GANESHPURE, Thiago Batista SOEIRO, Mohamad Ghaffarian NIASAR, Yang WU, Peter VAESSEN [View]
[Download]

Abstract: In order to damp the resonance in the MMC-based Arbitrary Wave shape Generator (AWG) used for high voltage testing, an active damping control methodology is proposed in this paper instead of the passive damping with an arm resistor. It is vital to ensure the system's stability when such an active damping closed loop control is implemented. Consequently, optimal parameters of a PI controller are designed by analyzing the stability margins of the involved transfer function using Bode-Plots. The performance of the designed active damping control methodology and the PI controller have been demonstrated with a 50 Hz sinusoidal waveform and arbitrary waveforms such as triangular, trapezoidal, and complex waveforms in MATLAB-Simulink. These results proves that the output voltage can track the reference without any reasonable error and does not contain any resonant frequency. Additionally, the Total Harmonic Distortion (THD) of the sinusoidal waveform and other arbitrary waveforms is less than 1\% with the Phase Shift Carrier (PSC) modulation technique.

   Model Predictive Control of Modular Multilevel Converter with High Number of Submodules
By Hussein KADHUM, Watson ALAN, Beeond M. SALEH, Rivera MARCO, Zanchetta PERICLE, Wheeler PATRICK [View]
[Download]

Abstract: This paper proposes a Level Model Predictive Control strategy combined with a pre-processing sorting algorithm to address the processing time issue of predictive control for Modular Multilevel Converters (MMCs) with hundreds of submodules. Five control objectives are optimized in a single cost function, resulting in good performance under a range of operating conditions, validated using PLECs simulation results.

   Modular Multilevel DC Converter : Impact of the Control on the Design and Efficiency
By Johan BOUKHENFOUF, François GRUSON, Pierre VERMEERSCH, Philippe DELARUE, Philippe LE MOIGNE, Frédéric COLAS, Xavier GUILLAUD [View]
[Download]

Abstract: The Modular Multilevel DC Converter is an attractive non-isolated topology to inter- connect HighVoltage DC Links. This paper presents the interaction among control, component design and efficiency of this converter. The impact of the two degrees of freedom on the design and the efficiency is analyzed.

   Neural Network Controller Based on Direct and Indirect Model Predictive for Modular Multilevel Converters
By Niloufar YOUSEFI, Javad EBRAHIMI, Alireza BAKHSHAI [View]
[Download]

Abstract: This study compares control methods for Modular Multilevel Converters (MMC) in power electronics, proposing the use of artificial neural networks as an alternative solution to conventional model predictive control (MPC) with reduced calculation burden. Simulation results of an MMC with four submodules are presented.

   Optimization of Control Parameters of Modular-Multilevel Converters in HVDC transmission applications
By Ivan BRAZ SCARPA PEREIRA, Rodrigo TEIXEIRA PINTO, Epameinondas KONTOS, Asimenia KOROMPILI, Antonello MONTI [View]
[Download]

Abstract: As modular-multilevel converter (MMC) has a complex control structure, the performance goals are difficult to achieve analytically when considered simultaneously. This paper presents a methodology to simultaneously address multiple control objectives, such as controller bandwidth, damping capability and converter impedance. To tune the MMC's control parameters a multi-objective particle swarm optimization (MOPSO) is employed. Simulation results in EMTDC show that with this approach the control and dynamic performance of the HVDC transmission link is enhanced and its stabilityimproved.

   Optimized Stationary Operating Regime and Common-Mode Voltage Design for Modular Multilevel Converters in Drive Applications at High Frequency
By Qiuye GUI, Hendrik FEHR, Albrecht GENSIOR [View]
[Download]

Abstract: For modular multilevel converters in drive applications, a special low-frequency mode resulting inadditional high current stress is generally utilized in the range around zero stator electrical frequency, since the conventional high-frequency mode for a higher frequency range may cause unaccepted large energy ripples in this low frequency range. To reduce the range for the undesired low-frequency mode, this paper aims on improving the high-frequency operation mode in terms of effectively reducing the cell capacitor voltage fluctuation, by means of a proposed online-implemented optimized stationary operating regime in cooperation with a new choice for the common-mode voltage which is designed under consideration of the energy ripples. Experiments confirm that the proposals lead to smaller cell capacitor voltage fluctuation than published variants, especially at relatively low frequencies.

   Reduced 8-Branch Modular Multilevel Matrix Converter with an Operating Point Optimised Control Strategy in a Branch Failure Event
By Rebecca HIMKER, Axel MERTENS [View]
[Download]

Abstract: In this paper, the reduction of the modular multilevel matrix converter (M3C) to eight branches is investigated in a branch failure event. In order to operate this reduced topology, circulating currents have to be injected so that the branch power imbalance caused by the asymmetrical branch configuration can be compensated. Using an analytical model, a novel approach is derivedin which the circulating currents are selected in such a way that the branch current losses and the branch energy variations are reduced. The novel approach is comparedto other reduced topologies in terms of branch losses and branch energy variations at different operating points.

   Voltage class comparison of 3.3 kV SiC and 6.5 kV SiC Devices in the Application of HVDC Converters
By Lukas BERGMANN, Marcus WAHLE, Mark-M. BAKRAN [View]
[Download]

Abstract: This work contains a comparison of voltage classes for High Voltage Silicon Carbide devices in the application of Multilevel converters. First a theoretical analysis on device technology parameters is executed to predicate the optimum voltage class of Silicon Carbide devices for highest output power. After this a comparison for static and dynamic device characteristics is performed in a scaled hardware test setup. This data is used for a final converter system benchmark in a loss simulation tool. Furthermore the potential impact of Silicon Carbide super junction devices on the application is discussed based on a previous paper.

EPE 2023 - DS1d: Modular Multilevel Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2023 ECCE Europe - Conference > EPE 2023 - Topic 02: Power Converter Topologies and Design > EPE 2023 - DS1d: Modular Multilevel Converters
	[return to parent folder]

	A Multilevel DC-Link Converter for VSC-HVDC Application By Biao ZHAO, Ruihang BAI, Xueyin ZHANG, Yushuo CHEN, Zhanqing YU, Qiang SONG, Rong ZENG	[View] [Download]
Abstract: This paper proposes a novel topology of AC-DC converter with multilevel DC-link. Sub-valves are connected in series to generate a DC voltage with interleaved superimposition. Each sub-valve includes both a switched-capacitor chain to generate modulation waveform and a H-bridge to half-flip the wave. Modular-designed units help to realize the voltage sharing as well as the floating supply of IGBTs. Its mathematical model is analyzed in detail. Then the voltage regulation method and optimal operating point is given. Finally, the feasibility is verified by simulation. Compared with MMC, the arm capacitance and IGBT devices in MDC are reduced 86\% and 14.8\% respectively. It has significant technical economy and prospect in VSC-HVDC application.

	An Improved Reduced Parallel Modular Multilevel Converter with Sensorless Capacitor Voltage Balancing By Mostafa ABARZADEH, Masoud AFSHARI, Simon CARON, Saeed PEYGHAMI, Kamal AL-HADDAD	[View] [Download]
Abstract: A new improved reduced parallel modular multilevel converter (RP-MMC) and its generalized topology are proposed in this paper. First, a basic four-level dc cell as well as its improved switching pattern to achieve sensorless voltage balancing of the capacitors is proposed. Then, a seven-level inverter is obtained by applying a low-frequency H-bridge to the proposed four-level dc cell. In addition, generalized topology of the proposed reduced multilevel dc cell is presented and described.Moreover, a new sensorless modified nearest level control (MNLC) switching pattern is proposed for the RP-MMC. The presented experimental results verify the feasibility and viability of the proposed seven-level inverter as well as the proposed MNLC modulation technique.

	Energy based and non-energy based control strategies for Modular Multilevel Converter with embedded storage By Hind BEKKOURI, Abdelkrim BENCHAIB, Florent MOREL, Pierre RAULT, Juan-Carlos GONZALEZ, Florian ERRIGO	[View] [Download]
Abstract: This paper deals with a high voltage direct current (HVDC) system based on modular multilevel converter (MMC) with embedded energy storage capacity. The dynamic behavior of energy-based (EBC) and non-energy-based (NEBC) controls is analyzed and compared for balanced and unbalanced energy storage distribution. EMTP simulations results show an equivalent performance for both controls when energy storage is balanced. While the NEBC control highlights limitations for unbalanced energy storage management, the EBC shows satisfactory overall performance.

	Enhanced Efficiency of MV Hybrid MMC under Extended Modulation using Si/SiC devices By Rajat SHAHANE, Poornachandra Rao NALLAMATTI, Anshuman SHUKLA	[View] [Download]
Abstract: The hybrid modular multilevel converter (MMC) consist of series connected half-bridge submodules (HBSMs) and full-bridge submodules (FBSMs) in each arms. The benefits of dc fault blocking and better dc link utilization in hybrid MMC have make them prominent choice for various medium voltage (MV) applications. However, with reduced SM count in MV hybrid MMC still requires additional filter due to the lower number of levels in the output voltage. This require larger filter which increases overall size and deteriorates the converter power density. The use of silicon carbide (SiC) MOSFETs over silicon (Si) IGBT allows high switching frequency operation which leads to reduced filter size, but increases overall cost. In this paper, a hybrid MMC is developed with Si/SiC based FBSM and Si based HBSM. Also, a novel modulation scheme is proposed which allocates all the high frequency function to the SiC devices while the Si devices are switched at relatively lower frequency. Further, simulation study and comparative loss analysis is carried out to prove the efficacy of the proposed system.

	Hybrid Implementation of Cascade Control for GaN-Based Modular Multilevel Converter for Low-Voltage Grid By Philip KIEHNLE, Niklas KATZENBURG, Lukas STEFANSKI, Marc HILLER	[View] [Download]
Abstract: A hybrid control system implementation for a Modular Multilevel Converter (MMC) prototype is presented in this paper. The cascade control using an ARM processor for the energy controller and a field programmable gate array (FPGA) for the current controllers, allows the GaN semiconductors to generate an output current with an effective ripple frequency of 200 kHz. The MMC system model and the partitioning of the cascade control are shown. With its dynamic current limit, implemented in the FPGA, the MMC is able to provide AC currents above the nominal current. Finally, prototype measurements of an emulated grid fault are shown.

	Impact of pole-to-pole dc voltage on energy requirement of FB YY-MMC By Sohrab MOHTAT, Massimo BONGIORNO, Mebtu BEZA, Jan R. SVENSSON	[View] [Download]
Abstract: The aim of this paper is to investigate the impact of pole-to-pole DC voltage on the energy requirements of a modular multilevel converter with full-bridge submodules (FB-MMC). With focus on energy-storage equipped FB-MMCs, the relation between the pole-to-pole voltage and the peak-to-peak energy variations in the MMC's arms is derived. Unlike MMC with half-bridge (HB) submodules (SM), in a FB-MMC the pole-to- pole DC voltage can be selected independently of the AC voltage; this allows for reduced energy requirements as well as lower number of FB SMs and capacitors for the same converter ratings. Furthermore, the impact of the converter's circulating current on the MMC's energy requirements is investigated. A guideline for the converter design is provided. Theoretical findings are validated via time-domain simulations.

	Implementation of Active Damping Control Methodology on Modular Multilevel Converter(MMC)-Based Arbitrary Wave Shape Generator Used for High Voltage Testing By Xiaochuan ZHOU, Dhanashree Ashok GANESHPURE, Thiago Batista SOEIRO, Mohamad Ghaffarian NIASAR, Yang WU, Peter VAESSEN	[View] [Download]
Abstract: In order to damp the resonance in the MMC-based Arbitrary Wave shape Generator (AWG) used for high voltage testing, an active damping control methodology is proposed in this paper instead of the passive damping with an arm resistor. It is vital to ensure the system's stability when such an active damping closed loop control is implemented. Consequently, optimal parameters of a PI controller are designed by analyzing the stability margins of the involved transfer function using Bode-Plots. The performance of the designed active damping control methodology and the PI controller have been demonstrated with a 50 Hz sinusoidal waveform and arbitrary waveforms such as triangular, trapezoidal, and complex waveforms in MATLAB-Simulink. These results proves that the output voltage can track the reference without any reasonable error and does not contain any resonant frequency. Additionally, the Total Harmonic Distortion (THD) of the sinusoidal waveform and other arbitrary waveforms is less than 1\% with the Phase Shift Carrier (PSC) modulation technique.

	Model Predictive Control of Modular Multilevel Converter with High Number of Submodules By Hussein KADHUM, Watson ALAN, Beeond M. SALEH, Rivera MARCO, Zanchetta PERICLE, Wheeler PATRICK	[View] [Download]
Abstract: This paper proposes a Level Model Predictive Control strategy combined with a pre-processing sorting algorithm to address the processing time issue of predictive control for Modular Multilevel Converters (MMCs) with hundreds of submodules. Five control objectives are optimized in a single cost function, resulting in good performance under a range of operating conditions, validated using PLECs simulation results.

	Modular Multilevel DC Converter : Impact of the Control on the Design and Efficiency By Johan BOUKHENFOUF, François GRUSON, Pierre VERMEERSCH, Philippe DELARUE, Philippe LE MOIGNE, Frédéric COLAS, Xavier GUILLAUD	[View] [Download]
Abstract: The Modular Multilevel DC Converter is an attractive non-isolated topology to inter- connect HighVoltage DC Links. This paper presents the interaction among control, component design and efficiency of this converter. The impact of the two degrees of freedom on the design and the efficiency is analyzed.

	Neural Network Controller Based on Direct and Indirect Model Predictive for Modular Multilevel Converters By Niloufar YOUSEFI, Javad EBRAHIMI, Alireza BAKHSHAI	[View] [Download]
Abstract: This study compares control methods for Modular Multilevel Converters (MMC) in power electronics, proposing the use of artificial neural networks as an alternative solution to conventional model predictive control (MPC) with reduced calculation burden. Simulation results of an MMC with four submodules are presented.

	Optimization of Control Parameters of Modular-Multilevel Converters in HVDC transmission applications By Ivan BRAZ SCARPA PEREIRA, Rodrigo TEIXEIRA PINTO, Epameinondas KONTOS, Asimenia KOROMPILI, Antonello MONTI	[View] [Download]
Abstract: As modular-multilevel converter (MMC) has a complex control structure, the performance goals are difficult to achieve analytically when considered simultaneously. This paper presents a methodology to simultaneously address multiple control objectives, such as controller bandwidth, damping capability and converter impedance. To tune the MMC's control parameters a multi-objective particle swarm optimization (MOPSO) is employed. Simulation results in EMTDC show that with this approach the control and dynamic performance of the HVDC transmission link is enhanced and its stabilityimproved.

	Optimized Stationary Operating Regime and Common-Mode Voltage Design for Modular Multilevel Converters in Drive Applications at High Frequency By Qiuye GUI, Hendrik FEHR, Albrecht GENSIOR	[View] [Download]
Abstract: For modular multilevel converters in drive applications, a special low-frequency mode resulting inadditional high current stress is generally utilized in the range around zero stator electrical frequency, since the conventional high-frequency mode for a higher frequency range may cause unaccepted large energy ripples in this low frequency range. To reduce the range for the undesired low-frequency mode, this paper aims on improving the high-frequency operation mode in terms of effectively reducing the cell capacitor voltage fluctuation, by means of a proposed online-implemented optimized stationary operating regime in cooperation with a new choice for the common-mode voltage which is designed under consideration of the energy ripples. Experiments confirm that the proposals lead to smaller cell capacitor voltage fluctuation than published variants, especially at relatively low frequencies.

	Reduced 8-Branch Modular Multilevel Matrix Converter with an Operating Point Optimised Control Strategy in a Branch Failure Event By Rebecca HIMKER, Axel MERTENS	[View] [Download]
Abstract: In this paper, the reduction of the modular multilevel matrix converter (M3C) to eight branches is investigated in a branch failure event. In order to operate this reduced topology, circulating currents have to be injected so that the branch power imbalance caused by the asymmetrical branch configuration can be compensated. Using an analytical model, a novel approach is derivedin which the circulating currents are selected in such a way that the branch current losses and the branch energy variations are reduced. The novel approach is comparedto other reduced topologies in terms of branch losses and branch energy variations at different operating points.

	Voltage class comparison of 3.3 kV SiC and 6.5 kV SiC Devices in the Application of HVDC Converters By Lukas BERGMANN, Marcus WAHLE, Mark-M. BAKRAN	[View] [Download]
Abstract: This work contains a comparison of voltage classes for High Voltage Silicon Carbide devices in the application of Multilevel converters. First a theoretical analysis on device technology parameters is executed to predicate the optimum voltage class of Silicon Carbide devices for highest output power. After this a comparison for static and dynamic device characteristics is performed in a scaled hardware test setup. This data is used for a final converter system benchmark in a loss simulation tool. Furthermore the potential impact of Silicon Carbide super junction devices on the application is discussed based on a previous paper.