IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022
In this paper two Power Factor Corrector (PFC) control strategies for a bidirectional Inductive P... more In this paper two Power Factor Corrector (PFC) control strategies for a bidirectional Inductive Power Transfer (IPT) system are proposed. These control strategies are presented for a novel power circuit without input and output interfaces for a wireless electric vehicle battery charger application. This compact topology is comprised of: unfolding rectifier, primary resonant bridge and secondary-side active rectification. Two PFC controls are described in detail: a primary-side PFC control, performed in the primary resonant bridge; and a secondary-side PFC control, implemented in the secondary-side active rectification stage. Both strategies are based on a duty-cycle control operating close to the resonance frequency, integrating different functionalities, i.e. PFC, current shaping and power control on a single control strategy. We analyze each control strategy, evaluating them for different operating points of the charging process. The performance of the wireless charger applying both control strategies is evaluated in terms of power losses, power factor, harmonic distortion and bifurcation. Additionally, the theoretical results are validated using a GaN-based experimental prototype. The presented analysis and experimental results clearly identify the advantages and limitations of each control strategy leaving no doubt about their usefulness for the future IPT systems.
2020 IEEE Vehicle Power and Propulsion Conference (VPPC), 2020
This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for dc-dc converter app... more This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for dc-dc converter applied to the control of Hybrid Energy Storage Systems (HESSs). Benefits and limitations of GaN-based power converters are identified for near future HESSs. Moreover, design considerations of the power converter are analyzed, identifying the most differential characteristics. Then, the performance of the power converter is evaluated in (b) terms of power losses and volume. The assembled experimental prototype is also presented, in order to validate the theoretical analysis.
2021 IEEE Vehicle Power and Propulsion Conference (VPPC), 2021
In this paper, an ultra-versatile power converter based on a multi-winding flyback transformer is... more In this paper, an ultra-versatile power converter based on a multi-winding flyback transformer is presented for EV application. Although the power converter concept, presented as Multi-cell Multi-port Bidirectional Flyback (M2BF), was initially proposed to interconnect several DC loads and/or sources, this paper proposes different configurations based on M2BF to interconnect and isolate different ports of an Electric Vehicle (EV), such as AC grid, High Voltage (HV) battery or Low Voltage (LV) battery. Numerous configurations are presented for each EV functionality, remarking the main differences and advantages respect to other configurations or SoA solutions. The main idea is to create a single power converter that performs the main functionalities of the EV, integrating several converters in a single circuit.
2021 IEEE Vehicle Power and Propulsion Conference (VPPC), 2021
This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for Inductive Power Tra... more This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for Inductive Power Transfer (IPT) applied to electric mobility. Benefits and limitations of GaN devices are evaluated for the resonant stage of the IPT. An IPT system presents different operating regions, which affects directly to the switching mode of power semiconductors. The performance of GaN-based power stage is analytically evaluated working on resistive, capacitive and inductive operating regions. Power losses breakdown of power devices is presented analyzing the impact of GaN devices on the performance of the power converter. In addition, the presented results are validated through experimental measurements.
2018 20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe), 2018
Gallium Nitride (GaN) devices are game-changing power electronics due to low conduction and switc... more Gallium Nitride (GaN) devices are game-changing power electronics due to low conduction and switching power loss characteristics. However, their small size brings up new cooling challenges for its implementation in high-power converters. This paper compares thermal performance of different cooling configurations, looking for the optimal cooling solution to develop compact power converters based on GaN devices. The proposed thermal analysis and performance comparison are experimentally validated comparing top and bottom side cooling solutions.
2019 IEEE Energy Conversion Congress and Exposition (ECCE), 2019
This paper proposes the novel Multi-cell Multi-port Bidirectional Flyback (M2BF), which is suitab... more This paper proposes the novel Multi-cell Multi-port Bidirectional Flyback (M2BF), which is suitable for applications with high-controllability requirement. Moreover, control strategy of the proposed converter and design considerations are analyzed, identifying the most differential characteristics. The main advantage of M2BF is the possibility of configuring the number of connected cells according to the specifications of the system. Besides, an independent control of each cell is proposed with a bidirectional power flow. The assembled experimental prototype is also presented, in order to validate the proposed concept.
2021 IEEE Energy Conversion Congress and Exposition (ECCE), 2021
This work proposes an optimized synchronous operation of bidirectional active clamps for the nove... more This work proposes an optimized synchronous operation of bidirectional active clamps for the novel Multi-cell Multiport Bidirectional Flyback (M2BF). Active-clamp circuits in both sides enable zero-voltage switching in all transistors, minimizing switching losses. Moreover, this work presents an optimization of transistors gates sequence based on an intervals estimator to have fully synchronous operation in the secondary transistors and to reduce free-wheeling conduction losses, specially critical in GaN-based converters. Power losses can be reduced by 40%, resulting in high-efficiency solution for an output power of 120 W. Experimental measurements with a GaN-based prototype validate the proposed method.
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
The use of Gallium Nitride (GaN) devices allows breaking the performance barriers of conventional... more The use of Gallium Nitride (GaN) devices allows breaking the performance barriers of conventional silicon-based (Si) low power converters by increasing the operating frequency while reducing system power losses. This paper evaluates the influence of the current ripple, switching frequency and number of GaN devices on the performance of a bi-directional buck converter. Furthermore, hard-switching and soft-switching operation modes are evaluated, identifying the optimal operation conditions for GaN-based power converters. Analytical and simulation models are employed and the obtained results are experimentally validated on a 3 kW GaN-based bi-directional buck converter.
IEEE Transactions on Transportation Electrification, 2021
In this article, a revolutionary and novel single-stage, multiport power conversion block is prop... more In this article, a revolutionary and novel single-stage, multiport power conversion block is proposed. The power conversion concept is based on a bidirectional flyback converter with four-quadrant switches that permit us to seamlessly control the direction of the energy flow and to select which ports are active. This approach, denominated as multicell multiport bidirectional flyback (M2BF), can be used as a modular and a multifunction building block interfacing ac and dc sources and loads in complex conversion systems like the one we can encounter in electric vehicle (EV) applications. The multiport property is obtained due to the multiwinding flyback transformer that interfaces different sources and loads in a simple and effective way. We present and analyze this concept in detail, focusing on different operation modes it can provide (multiport dc–dc conversion, ac–dc conversion, vehicle-to-grid, grid-to-vehicle, and so on) and their possible implementation in the energy distribution network of an EV, where this unique multifunction multiport converter could bring an important breakthrough. The operating principles of the M2BF for different operating modes are described and analyzed, placing emphasis on the modularity of the proposed concept. The overall concept is evaluated and quantified using a gallium nitride (GaN)-based prototype achieving efficiencies higher than 91% that additionally validates the proposed idea experimentally. The presented analysis and experimental results clearly identify the advantages and limitations of the presented concept leaving no doubt about its usefulness to the future EV distribution network.
Lithium-ion (Li-ion) batteries are still the best technology to power the Electric Vehicle (EV), ... more Lithium-ion (Li-ion) batteries are still the best technology to power the Electric Vehicle (EV), due to their high power and energy density. However, the use of these batteries can be limited in cars with a high demand for peak power and very high energy density. One way to improve the performance of the Li-ion battery and reduce its weight is to associate this battery with another technology of higher specific energy as a second energy source, e.g. Lithium-sulfur (Li-S). The development of Hybrid Energy Storage Systems (HESSs) is a promising solution optimizing the energy management of EVs. In this paper, we present experimental results obtained with a high specific energy and power capability HESS prototype, composed of i) a Lithium-Titanate-Oxide battery to ensure high power capabilities, ii) a Li-S battery to improve specific energy, and iii) a power converter based on Gallium Nitride (GaN) devices to link both battery modules, minimizing at the same time system weight, volume and power losses. The developed GaN-based power converter achieves high efficiency (96.5%) operating at 300 kHz with a reduced size (0.4 L). Besides, the behavior of the developed HESS prototype is experimentally evaluated under standard automotive profiles, for different driving scenarios. The HESS prototype achieves an increase of energy density and specific energy of +5.56% and +28.21%, respectively, compared to a battery system composed only of Li-ion cells. The limitation of the developed system for automotive application are highlighted, and the critical research needs are clearly identified to accelerate the implementation of such systems on commercial EV solutions.
Inductive power transfer (IPT) is widely discussed as an alternative to contact charger for plug-... more Inductive power transfer (IPT) is widely discussed as an alternative to contact charger for plug-in hybrid and electric vehicles (PHEV/EV). This paper analyzes a contactless battery charger back end power factor correction (PFC) concept, reducing the primary side circuit complexity and physical size. For that purpose, the main volume and loss factors of a contactless battery charger are identified, discussing the partitioning of tasks to perform a unity power factor operation. An analysis of the most commonly used front end PFC and the proposed back end PFC configuration is performed, with the aim of highlighting benefits and limitations of each variant. Moreover, performance of silicon (Si) and gallium nitride (GaN) devices has been also evaluated, defining the main advantages and drawbacks of both semiconductor technologies in different IPT scenarios. The study is verified experimentally on a 3.2 kW contactless battery charger. Index Terms-power factor correction (PFC), gallium nitride (GaN), inductive power transfer (IPT), bifurcation, battery chargers 10 Alejandro Rujas received the B.Sc. degree in electronics from the University of Mondragón, Spain, in 2004, and the M.Sc. degree in electrical engineering from the
2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), 2017
The performance of a Modular Multilevel Converter (MMC) is presented in this paper, comparing Sil... more The performance of a Modular Multilevel Converter (MMC) is presented in this paper, comparing Silicon (Si) and Gallium Nitride (GaN) semiconductors. Moreover, the benefits of high-frequency operation in a MMC topology are analysed along with a power loss distribution evaluation, highlighting the main advantages and drawbacks of different semiconductor technologies.
IEEE Journal of Emerging and Selected Topics in Power Electronics, 2022
In this paper two Power Factor Corrector (PFC) control strategies for a bidirectional Inductive P... more In this paper two Power Factor Corrector (PFC) control strategies for a bidirectional Inductive Power Transfer (IPT) system are proposed. These control strategies are presented for a novel power circuit without input and output interfaces for a wireless electric vehicle battery charger application. This compact topology is comprised of: unfolding rectifier, primary resonant bridge and secondary-side active rectification. Two PFC controls are described in detail: a primary-side PFC control, performed in the primary resonant bridge; and a secondary-side PFC control, implemented in the secondary-side active rectification stage. Both strategies are based on a duty-cycle control operating close to the resonance frequency, integrating different functionalities, i.e. PFC, current shaping and power control on a single control strategy. We analyze each control strategy, evaluating them for different operating points of the charging process. The performance of the wireless charger applying both control strategies is evaluated in terms of power losses, power factor, harmonic distortion and bifurcation. Additionally, the theoretical results are validated using a GaN-based experimental prototype. The presented analysis and experimental results clearly identify the advantages and limitations of each control strategy leaving no doubt about their usefulness for the future IPT systems.
2020 IEEE Vehicle Power and Propulsion Conference (VPPC), 2020
This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for dc-dc converter app... more This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for dc-dc converter applied to the control of Hybrid Energy Storage Systems (HESSs). Benefits and limitations of GaN-based power converters are identified for near future HESSs. Moreover, design considerations of the power converter are analyzed, identifying the most differential characteristics. Then, the performance of the power converter is evaluated in (b) terms of power losses and volume. The assembled experimental prototype is also presented, in order to validate the theoretical analysis.
2021 IEEE Vehicle Power and Propulsion Conference (VPPC), 2021
In this paper, an ultra-versatile power converter based on a multi-winding flyback transformer is... more In this paper, an ultra-versatile power converter based on a multi-winding flyback transformer is presented for EV application. Although the power converter concept, presented as Multi-cell Multi-port Bidirectional Flyback (M2BF), was initially proposed to interconnect several DC loads and/or sources, this paper proposes different configurations based on M2BF to interconnect and isolate different ports of an Electric Vehicle (EV), such as AC grid, High Voltage (HV) battery or Low Voltage (LV) battery. Numerous configurations are presented for each EV functionality, remarking the main differences and advantages respect to other configurations or SoA solutions. The main idea is to create a single power converter that performs the main functionalities of the EV, integrating several converters in a single circuit.
2021 IEEE Vehicle Power and Propulsion Conference (VPPC), 2021
This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for Inductive Power Tra... more This paper analyzes and proposes the use of Gallium Nitride (GaN) devices for Inductive Power Transfer (IPT) applied to electric mobility. Benefits and limitations of GaN devices are evaluated for the resonant stage of the IPT. An IPT system presents different operating regions, which affects directly to the switching mode of power semiconductors. The performance of GaN-based power stage is analytically evaluated working on resistive, capacitive and inductive operating regions. Power losses breakdown of power devices is presented analyzing the impact of GaN devices on the performance of the power converter. In addition, the presented results are validated through experimental measurements.
2018 20th European Conference on Power Electronics and Applications (EPE'18 ECCE Europe), 2018
Gallium Nitride (GaN) devices are game-changing power electronics due to low conduction and switc... more Gallium Nitride (GaN) devices are game-changing power electronics due to low conduction and switching power loss characteristics. However, their small size brings up new cooling challenges for its implementation in high-power converters. This paper compares thermal performance of different cooling configurations, looking for the optimal cooling solution to develop compact power converters based on GaN devices. The proposed thermal analysis and performance comparison are experimentally validated comparing top and bottom side cooling solutions.
2019 IEEE Energy Conversion Congress and Exposition (ECCE), 2019
This paper proposes the novel Multi-cell Multi-port Bidirectional Flyback (M2BF), which is suitab... more This paper proposes the novel Multi-cell Multi-port Bidirectional Flyback (M2BF), which is suitable for applications with high-controllability requirement. Moreover, control strategy of the proposed converter and design considerations are analyzed, identifying the most differential characteristics. The main advantage of M2BF is the possibility of configuring the number of connected cells according to the specifications of the system. Besides, an independent control of each cell is proposed with a bidirectional power flow. The assembled experimental prototype is also presented, in order to validate the proposed concept.
2021 IEEE Energy Conversion Congress and Exposition (ECCE), 2021
This work proposes an optimized synchronous operation of bidirectional active clamps for the nove... more This work proposes an optimized synchronous operation of bidirectional active clamps for the novel Multi-cell Multiport Bidirectional Flyback (M2BF). Active-clamp circuits in both sides enable zero-voltage switching in all transistors, minimizing switching losses. Moreover, this work presents an optimization of transistors gates sequence based on an intervals estimator to have fully synchronous operation in the secondary transistors and to reduce free-wheeling conduction losses, specially critical in GaN-based converters. Power losses can be reduced by 40%, resulting in high-efficiency solution for an output power of 120 W. Experimental measurements with a GaN-based prototype validate the proposed method.
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
The use of Gallium Nitride (GaN) devices allows breaking the performance barriers of conventional... more The use of Gallium Nitride (GaN) devices allows breaking the performance barriers of conventional silicon-based (Si) low power converters by increasing the operating frequency while reducing system power losses. This paper evaluates the influence of the current ripple, switching frequency and number of GaN devices on the performance of a bi-directional buck converter. Furthermore, hard-switching and soft-switching operation modes are evaluated, identifying the optimal operation conditions for GaN-based power converters. Analytical and simulation models are employed and the obtained results are experimentally validated on a 3 kW GaN-based bi-directional buck converter.
IEEE Transactions on Transportation Electrification, 2021
In this article, a revolutionary and novel single-stage, multiport power conversion block is prop... more In this article, a revolutionary and novel single-stage, multiport power conversion block is proposed. The power conversion concept is based on a bidirectional flyback converter with four-quadrant switches that permit us to seamlessly control the direction of the energy flow and to select which ports are active. This approach, denominated as multicell multiport bidirectional flyback (M2BF), can be used as a modular and a multifunction building block interfacing ac and dc sources and loads in complex conversion systems like the one we can encounter in electric vehicle (EV) applications. The multiport property is obtained due to the multiwinding flyback transformer that interfaces different sources and loads in a simple and effective way. We present and analyze this concept in detail, focusing on different operation modes it can provide (multiport dc–dc conversion, ac–dc conversion, vehicle-to-grid, grid-to-vehicle, and so on) and their possible implementation in the energy distribution network of an EV, where this unique multifunction multiport converter could bring an important breakthrough. The operating principles of the M2BF for different operating modes are described and analyzed, placing emphasis on the modularity of the proposed concept. The overall concept is evaluated and quantified using a gallium nitride (GaN)-based prototype achieving efficiencies higher than 91% that additionally validates the proposed idea experimentally. The presented analysis and experimental results clearly identify the advantages and limitations of the presented concept leaving no doubt about its usefulness to the future EV distribution network.
Lithium-ion (Li-ion) batteries are still the best technology to power the Electric Vehicle (EV), ... more Lithium-ion (Li-ion) batteries are still the best technology to power the Electric Vehicle (EV), due to their high power and energy density. However, the use of these batteries can be limited in cars with a high demand for peak power and very high energy density. One way to improve the performance of the Li-ion battery and reduce its weight is to associate this battery with another technology of higher specific energy as a second energy source, e.g. Lithium-sulfur (Li-S). The development of Hybrid Energy Storage Systems (HESSs) is a promising solution optimizing the energy management of EVs. In this paper, we present experimental results obtained with a high specific energy and power capability HESS prototype, composed of i) a Lithium-Titanate-Oxide battery to ensure high power capabilities, ii) a Li-S battery to improve specific energy, and iii) a power converter based on Gallium Nitride (GaN) devices to link both battery modules, minimizing at the same time system weight, volume and power losses. The developed GaN-based power converter achieves high efficiency (96.5%) operating at 300 kHz with a reduced size (0.4 L). Besides, the behavior of the developed HESS prototype is experimentally evaluated under standard automotive profiles, for different driving scenarios. The HESS prototype achieves an increase of energy density and specific energy of +5.56% and +28.21%, respectively, compared to a battery system composed only of Li-ion cells. The limitation of the developed system for automotive application are highlighted, and the critical research needs are clearly identified to accelerate the implementation of such systems on commercial EV solutions.
Inductive power transfer (IPT) is widely discussed as an alternative to contact charger for plug-... more Inductive power transfer (IPT) is widely discussed as an alternative to contact charger for plug-in hybrid and electric vehicles (PHEV/EV). This paper analyzes a contactless battery charger back end power factor correction (PFC) concept, reducing the primary side circuit complexity and physical size. For that purpose, the main volume and loss factors of a contactless battery charger are identified, discussing the partitioning of tasks to perform a unity power factor operation. An analysis of the most commonly used front end PFC and the proposed back end PFC configuration is performed, with the aim of highlighting benefits and limitations of each variant. Moreover, performance of silicon (Si) and gallium nitride (GaN) devices has been also evaluated, defining the main advantages and drawbacks of both semiconductor technologies in different IPT scenarios. The study is verified experimentally on a 3.2 kW contactless battery charger. Index Terms-power factor correction (PFC), gallium nitride (GaN), inductive power transfer (IPT), bifurcation, battery chargers 10 Alejandro Rujas received the B.Sc. degree in electronics from the University of Mondragón, Spain, in 2004, and the M.Sc. degree in electrical engineering from the
2017 19th European Conference on Power Electronics and Applications (EPE'17 ECCE Europe), 2017
The performance of a Modular Multilevel Converter (MMC) is presented in this paper, comparing Sil... more The performance of a Modular Multilevel Converter (MMC) is presented in this paper, comparing Silicon (Si) and Gallium Nitride (GaN) semiconductors. Moreover, the benefits of high-frequency operation in a MMC topology are analysed along with a power loss distribution evaluation, highlighting the main advantages and drawbacks of different semiconductor technologies.
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