EPE Association: EPE 2019 - DS3a: Advanced Power Converter Topologies IV

EPE 2019 - DS3a: Advanced Power Converter Topologies IV
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 02: Power Converter Topologies and Design > EPE 2019 - DS3a: Advanced Power Converter Topologies IV

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   A Novel Approach for Inter-Leg Balancing of a Three-Phase MMC in HDVC Applications
By Andrea CERVONE [View]
[Download]

Abstract: This paper proposes a harmonic balancing based approach to deal with the equalization process of thecapacitors stored energies in the six legs of a three-phase Multi Modular Converter (MMC) serving as theactive interface between an AC grid and a HVDC link. Indeed, the harmonic balancing control, applied tothe converter energies status variables written in a special form by exploiting the Space Vector/ZeroComponent and Common/Differential Mode decompositions, allows to highlight all the viable controllableinteractions able to constrain the MMC stored energies to the desired balanced status. The conceived voltagecontrol strategy is validated by an extensive numerical simulation.

   A Reconfigurable Multilevel Dual-Active-Bridge Converter for Wide-Range High-Efficiency Operation
By Yiu Pang CHAN [View]
[Download]

Abstract: A structurally reconfigurable DAB converter is proposed to minimize both conduction and switchinglosses. For 25\% to 100\% rated load, a new modulation scheme is proposed to achieve zero circulatingcurrent, zero backflow power, and full-range ZVS. Below 25\% rated load, it transitions smoothly to theEnhanced-Dual-Phase-Shift (EDPS) modulation which maintains zero backflow power and full-rangeZVS.

   Analysis of an LLC Converter with Planar Inverse Coupled Current Doubler Rectifier using Silicon and GaN devices
By Sebastian KLOETZER [View]
[Download]

Abstract: In this paper a 2kW 400 V/36V LLC converter with an inverse coupled planar current doubler rectifierwith minimized stray inductance is presented and assessed in conjunction with state of the art 100Vsilicon and gallium nitride power semiconductors. First, the general impact of the current doubler onZVS behaviour and turn-off overvoltage without a snubber circuit is discussed. Afterwards, two lowinductance planar coupled inductor designs are presented and their impact on performance and efficiency is evaluated. The proposed LLC converter with a multi-stack planar coupled inductor is able to reach an efficiency of more than 98\% at a switching frequency of 290 kHz and can be operated without snubber circuit, when the right combination of coupled inductor and transistor is chosen.

   Analysis of Circulating current in Two Parallel-Connected AC/DC/AC Converter
By Ramkrishan MAHESHWARI [View]
[Download]

Abstract: Parallel-connected ac/dc/ac converters are used to increase power capability and have redundancy in high power applications. However, due to parallel connection, there exists a circulating current which does not contribute to the ac side load or source currents and causes extra losses. This paper analyses the circulating current for two parallel-connected ac/dc/ac converter system. The ac/dc/ac converter system may have separate dc-links for each ac/dc/ac converter or a common dc-link. In both cases, the circulating currents are analyzed in this paper. The system with and without common dc-links are simulated, and the comparison of the circulating current and total ac side source and load currents in both cases are presented.

   Bidirectional AC to DC Isolated Multi-Cell Converter
By Thanh Hai PHUNG [View]
[Download]

Abstract: This paper presents the implementation of a bidirectional multi-level voltage inverter, isolated converter based on a multi-cell architecture for battery charger applications. Dual Active Bridge based DC to DC isolated converter cells are cascaded with H bridges which are then associated in series to implement a multi-level topology able to produce AC waves from DC source and vice versa. The operating principle is provided along with converter main advantages and drawbacks. A special attention is dedicated to the control part. The operation of the multi-level converter is validated with experimental results. A special care is applied to efficiency measurements. Efficiency and power densities are provided to highlight the interest of the converter.

   Comparison of Inductive Stored Energy in the Dual Active Half Bridge with and without Auxiliary Inductor Splitting
By Ngoni MUGWISI [View]
[Download]

Abstract: This paper presents a study of inductive stored energy and transformer RMS currents for a Dual Active Half Bridge (DAHB) operated with and without auxiliary inductor splitting. It is shown that distributing the auxiliary inductances between transformer windings is beneficial under unbalanced conditions because it reduces the inductive energy required to transfer a given power when compared to the lumped case.

   Design and operation of a fail-operational 5kW 800V-12V DC-DC converter
By Luigi PIEGARI [View]
[Download]

Abstract: The spreading of autonomous drive systems is causing the increase of electrical power request on the 12V vehicle power net because, more and more on-board actuators are realized with electrical drives. Moreover, a very important requirement for autonomous drive systems is the capability of each component to operate also after a failure. A fail operational DC/DC power converter is therefore necessary to achieve the 12V power-net derived from the main battery of electric vehicles. In this paper a fail operational DC-DC 800 V/12 V, 5 kW power converter for automotive application is proposed. The converter topology is designed to ensure operability after a single failure. In this work, the sizing design procedure of each component of the converter is presented. Moreover, a numerical model of the converter is built and used to test the power converter both in normal and faulty conditions. Numerical simulation results validate the proposed topology showing both good dynamic performances and the required fail operational capabilities.

   Field Oriented Control of a Modular Multilevel Matrix Converter based Variable Speed Drive
By Matías DIAZ [View]
[Download]

Abstract: The Modular Multilevel Matrix Converter (\mc{}) has been proposed as an appropriate alternative to driving high-power machines due to characteristics such as modularity, medium-voltage operation, high power quality, reliability. Nevertheless, the control of \mc{} is complicated, especially in variable-speed applications, because large voltage oscillations can be produced in the floating capacitors. Therefore, this paper presents a vector control system that allows decoupled regulation of the floating capacitors of the \mc{}, whereas Field Oriented Control (FOC) is applied to regulate an induction machine. The effectiveness of the proposed control system is validated through \mc{} simulation model composed of 63 power cells M3C driving a 1250 HP induction machine.

   Optimization of the Low-Frequency Mode for Modular Multilevel Converters Based On Frequency Domain Analysis
By Rebecca DIERKS [View]
[Download]

Abstract: The low-frequency mode is an established operation mode for modular multilevel converters, which enables the converter operation with machines at low speeds. This paper analyzes the operation mode in frequency domain using a simplified harmonic model. Based on the frequency domain model, an extension for the operation mode is proposed, which significantly reduces the current loading of the modules' semiconductors without increasing the module capacitance requirements. The simplified frequency domain models and the effectiveness of the proposed extension are validated using simulations and experimentally using a downscaled converter prototype.

   Optimized Real Time Control for Modular Multilevel Converter using Adaptive Neural Networks
By David KRAUS [View]
[Download]

Abstract: This paper presents a novel control approach using a Neural Network and reinforcement learning for Modular Multilevel Series Parallel Converters (MMSPCs). The MMSPC topology allows more _exible control than other multilevel converter topologies. This includes active balancing of temperature, minimizing of power loss due to internal resistance and current ripples and minimizing switching losses as well as harmonic distortion losses [1]. For ideal control, all of these parameters have to be weighted according to signi_cance, which changes during operation of the MMSPC. Due to multiple degrees of freedom which are mostly nonlinear, it is challenging to _nd the optimal scheduling strategy in conventional ways. This approach uses not only Neural Network (NN), but also reinforcement learning to optimize the controller in simulation and in an experimental setup. This leads to even more advantages such as compensating component tolerances and aging processes as well as faster computation time.

   Power Electronics Topology Comparison and Improvement for Low Voltage - High Current DC/AC Applications
By Alex BUUS NIELSEN [View]
[Download]

Abstract: In this paper, the power electronics topology and semiconductor selection for low voltage (115 VRMS phase voltage) and medium power (90 kW) DC/AC applications are presented. Since these special power electronic applications require a low phase voltage, the phase current is consequently higher. The higher current is shown to limit the maximum achievable efficiency compared to an industry standard 230 V converter, even though lower voltage rated semiconductors can be used for the 115 V converter. To explore a suitable topology for this special DC/AC converter application, a 2-level Si IGBT and a 2-level SiC MOSFET converter are compared to industry standard 3-level Si topologies using market available semiconductors. The comparison is realised using semiconductor loss models, and a comparatively LC filter loss model. The applied IGBT loss model is verified with a double pulse test (DPT) setup and finally, besides highlighting the suitable topology using a figure of merit and suitable semiconductor type, the advantage of utilizing an interleaving configuration is discussed for IGBT-based converters.

   Theoretical Analysis of Power Flow and Stored Energy in the Capacitor of Neutral-Point-Clamped Modular Multilevel Converter
By Takuro ARAI [View]
[Download]

Abstract: This paper describes theoretical analysis of a power flow and a total stored energy in the capacitor of a neutral-point-clamped modular multilevel converter (NPC-MMC). The NPC-MMC consists of both a three-level structure with common DC capacitors and chopper cells. It requires only half of chopper cells compared to the conventional MMC.In this paper, at first, theoretical analysis reveals the NPC-MMC can supply the AC power from not only the cells but also common DC capacitors. The direct power flow between the DC capacitors and the AC side brings 48\% reduction of the total stored energy in the cell capacitors and the DC capacitors to the conventional MMC.Secondary, the 10-kVA experimental circuit using low-voltage MOSFETs validates the capacitor energy analysis. Measured efficiency reaches extremely high value of 99.3\%. Therefore, it requires neither heat sink nor cooling fans. These experimental results show that the NPC-MMC can realize both downsizing and very high efficiency conversion.

   Topologies for high-voltage low-power integrated dc-dc converter
By Etienne FORAY [View]
[Download]

Abstract: The conversion from a high-input-voltage to a low-output-voltage with low-output-power and large efficiency is challenging, particularly if a limited voltage technology is considered for silicon integration. After presenting few criteria, the paper reviews possible topologies for silicon integration of active devices. A preliminary demonstrator is experimentally analyzed to draw conclusions and prepare the specifications of a future integrated circuit.

EPE 2019 - DS3a: Advanced Power Converter Topologies IV
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 02: Power Converter Topologies and Design > EPE 2019 - DS3a: Advanced Power Converter Topologies IV
	[return to parent folder]

	A Novel Approach for Inter-Leg Balancing of a Three-Phase MMC in HDVC Applications By Andrea CERVONE	[View] [Download]
Abstract: This paper proposes a harmonic balancing based approach to deal with the equalization process of thecapacitors stored energies in the six legs of a three-phase Multi Modular Converter (MMC) serving as theactive interface between an AC grid and a HVDC link. Indeed, the harmonic balancing control, applied tothe converter energies status variables written in a special form by exploiting the Space Vector/ZeroComponent and Common/Differential Mode decompositions, allows to highlight all the viable controllableinteractions able to constrain the MMC stored energies to the desired balanced status. The conceived voltagecontrol strategy is validated by an extensive numerical simulation.

	A Reconfigurable Multilevel Dual-Active-Bridge Converter for Wide-Range High-Efficiency Operation By Yiu Pang CHAN	[View] [Download]
Abstract: A structurally reconfigurable DAB converter is proposed to minimize both conduction and switchinglosses. For 25\% to 100\% rated load, a new modulation scheme is proposed to achieve zero circulatingcurrent, zero backflow power, and full-range ZVS. Below 25\% rated load, it transitions smoothly to theEnhanced-Dual-Phase-Shift (EDPS) modulation which maintains zero backflow power and full-rangeZVS.

	Analysis of an LLC Converter with Planar Inverse Coupled Current Doubler Rectifier using Silicon and GaN devices By Sebastian KLOETZER	[View] [Download]
Abstract: In this paper a 2kW 400 V/36V LLC converter with an inverse coupled planar current doubler rectifierwith minimized stray inductance is presented and assessed in conjunction with state of the art 100Vsilicon and gallium nitride power semiconductors. First, the general impact of the current doubler onZVS behaviour and turn-off overvoltage without a snubber circuit is discussed. Afterwards, two lowinductance planar coupled inductor designs are presented and their impact on performance and efficiency is evaluated. The proposed LLC converter with a multi-stack planar coupled inductor is able to reach an efficiency of more than 98\% at a switching frequency of 290 kHz and can be operated without snubber circuit, when the right combination of coupled inductor and transistor is chosen.

	Analysis of Circulating current in Two Parallel-Connected AC/DC/AC Converter By Ramkrishan MAHESHWARI	[View] [Download]
Abstract: Parallel-connected ac/dc/ac converters are used to increase power capability and have redundancy in high power applications. However, due to parallel connection, there exists a circulating current which does not contribute to the ac side load or source currents and causes extra losses. This paper analyses the circulating current for two parallel-connected ac/dc/ac converter system. The ac/dc/ac converter system may have separate dc-links for each ac/dc/ac converter or a common dc-link. In both cases, the circulating currents are analyzed in this paper. The system with and without common dc-links are simulated, and the comparison of the circulating current and total ac side source and load currents in both cases are presented.

	Bidirectional AC to DC Isolated Multi-Cell Converter By Thanh Hai PHUNG	[View] [Download]
Abstract: This paper presents the implementation of a bidirectional multi-level voltage inverter, isolated converter based on a multi-cell architecture for battery charger applications. Dual Active Bridge based DC to DC isolated converter cells are cascaded with H bridges which are then associated in series to implement a multi-level topology able to produce AC waves from DC source and vice versa. The operating principle is provided along with converter main advantages and drawbacks. A special attention is dedicated to the control part. The operation of the multi-level converter is validated with experimental results. A special care is applied to efficiency measurements. Efficiency and power densities are provided to highlight the interest of the converter.

	Comparison of Inductive Stored Energy in the Dual Active Half Bridge with and without Auxiliary Inductor Splitting By Ngoni MUGWISI	[View] [Download]
Abstract: This paper presents a study of inductive stored energy and transformer RMS currents for a Dual Active Half Bridge (DAHB) operated with and without auxiliary inductor splitting. It is shown that distributing the auxiliary inductances between transformer windings is beneficial under unbalanced conditions because it reduces the inductive energy required to transfer a given power when compared to the lumped case.

	Design and operation of a fail-operational 5kW 800V-12V DC-DC converter By Luigi PIEGARI	[View] [Download]
Abstract: The spreading of autonomous drive systems is causing the increase of electrical power request on the 12V vehicle power net because, more and more on-board actuators are realized with electrical drives. Moreover, a very important requirement for autonomous drive systems is the capability of each component to operate also after a failure. A fail operational DC/DC power converter is therefore necessary to achieve the 12V power-net derived from the main battery of electric vehicles. In this paper a fail operational DC-DC 800 V/12 V, 5 kW power converter for automotive application is proposed. The converter topology is designed to ensure operability after a single failure. In this work, the sizing design procedure of each component of the converter is presented. Moreover, a numerical model of the converter is built and used to test the power converter both in normal and faulty conditions. Numerical simulation results validate the proposed topology showing both good dynamic performances and the required fail operational capabilities.

	Field Oriented Control of a Modular Multilevel Matrix Converter based Variable Speed Drive By Matías DIAZ	[View] [Download]
Abstract: The Modular Multilevel Matrix Converter (\mc{}) has been proposed as an appropriate alternative to driving high-power machines due to characteristics such as modularity, medium-voltage operation, high power quality, reliability. Nevertheless, the control of \mc{} is complicated, especially in variable-speed applications, because large voltage oscillations can be produced in the floating capacitors. Therefore, this paper presents a vector control system that allows decoupled regulation of the floating capacitors of the \mc{}, whereas Field Oriented Control (FOC) is applied to regulate an induction machine. The effectiveness of the proposed control system is validated through \mc{} simulation model composed of 63 power cells M3C driving a 1250 HP induction machine.

	Optimization of the Low-Frequency Mode for Modular Multilevel Converters Based On Frequency Domain Analysis By Rebecca DIERKS	[View] [Download]
Abstract: The low-frequency mode is an established operation mode for modular multilevel converters, which enables the converter operation with machines at low speeds. This paper analyzes the operation mode in frequency domain using a simplified harmonic model. Based on the frequency domain model, an extension for the operation mode is proposed, which significantly reduces the current loading of the modules' semiconductors without increasing the module capacitance requirements. The simplified frequency domain models and the effectiveness of the proposed extension are validated using simulations and experimentally using a downscaled converter prototype.

	Optimized Real Time Control for Modular Multilevel Converter using Adaptive Neural Networks By David KRAUS	[View] [Download]
Abstract: This paper presents a novel control approach using a Neural Network and reinforcement learning for Modular Multilevel Series Parallel Converters (MMSPCs). The MMSPC topology allows more _exible control than other multilevel converter topologies. This includes active balancing of temperature, minimizing of power loss due to internal resistance and current ripples and minimizing switching losses as well as harmonic distortion losses [1]. For ideal control, all of these parameters have to be weighted according to signi_cance, which changes during operation of the MMSPC. Due to multiple degrees of freedom which are mostly nonlinear, it is challenging to _nd the optimal scheduling strategy in conventional ways. This approach uses not only Neural Network (NN), but also reinforcement learning to optimize the controller in simulation and in an experimental setup. This leads to even more advantages such as compensating component tolerances and aging processes as well as faster computation time.

	Power Electronics Topology Comparison and Improvement for Low Voltage - High Current DC/AC Applications By Alex BUUS NIELSEN	[View] [Download]
Abstract: In this paper, the power electronics topology and semiconductor selection for low voltage (115 VRMS phase voltage) and medium power (90 kW) DC/AC applications are presented. Since these special power electronic applications require a low phase voltage, the phase current is consequently higher. The higher current is shown to limit the maximum achievable efficiency compared to an industry standard 230 V converter, even though lower voltage rated semiconductors can be used for the 115 V converter. To explore a suitable topology for this special DC/AC converter application, a 2-level Si IGBT and a 2-level SiC MOSFET converter are compared to industry standard 3-level Si topologies using market available semiconductors. The comparison is realised using semiconductor loss models, and a comparatively LC filter loss model. The applied IGBT loss model is verified with a double pulse test (DPT) setup and finally, besides highlighting the suitable topology using a figure of merit and suitable semiconductor type, the advantage of utilizing an interleaving configuration is discussed for IGBT-based converters.

	Theoretical Analysis of Power Flow and Stored Energy in the Capacitor of Neutral-Point-Clamped Modular Multilevel Converter By Takuro ARAI	[View] [Download]
Abstract: This paper describes theoretical analysis of a power flow and a total stored energy in the capacitor of a neutral-point-clamped modular multilevel converter (NPC-MMC). The NPC-MMC consists of both a three-level structure with common DC capacitors and chopper cells. It requires only half of chopper cells compared to the conventional MMC.In this paper, at first, theoretical analysis reveals the NPC-MMC can supply the AC power from not only the cells but also common DC capacitors. The direct power flow between the DC capacitors and the AC side brings 48\% reduction of the total stored energy in the cell capacitors and the DC capacitors to the conventional MMC.Secondary, the 10-kVA experimental circuit using low-voltage MOSFETs validates the capacitor energy analysis. Measured efficiency reaches extremely high value of 99.3\%. Therefore, it requires neither heat sink nor cooling fans. These experimental results show that the NPC-MMC can realize both downsizing and very high efficiency conversion.

	Topologies for high-voltage low-power integrated dc-dc converter By Etienne FORAY	[View] [Download]
Abstract: The conversion from a high-input-voltage to a low-output-voltage with low-output-power and large efficiency is challenging, particularly if a limited voltage technology is considered for silicon integration. After presenting few criteria, the paper reviews possible topologies for silicon integration of active devices. A preliminary demonstrator is experimentally analyzed to draw conclusions and prepare the specifications of a future integrated circuit.