Periodic Reporting for period 1 - PORT-BICPD (Power Converters with Best In-Class Power Density)
Période du rapport: 2021-04-23 au 2023-04-22
The research project undertaken seeks to address a critical challenge in the development of light electric vehicle (EV) chargers, specifically in the creation of highly efficient, high power density power factor correction (PFC) pre-regulators. This issue is of paramount importance in light of the increasing adoption of electric vehicles, a significant shift that is integral to reducing greenhouse gas emissions and combatting climate change. An effective and efficient charging infrastructure is a cornerstone in supporting this move towards electric mobility. The project's focal point is the design of a 3.7 kW single-phase PFC converter prototype, which aims to achieve a power density of 85 W/in3 and a peak efficiency of 98.5%. Additionally, the project extends its scope to include a DC/DC converter stage for a 48V system in light EV chargers, with an ambitious target of 75 W/in3 power density and 97% efficiency. The task at hand is to engineer and optimize these converter designs using advanced Gallium Nitride (GaN) devices, modern ferrite materials, and a cross-disciplinary approach that blends various fields of engineering and material sciences.
From a societal perspective, this research bears significant importance in two primary aspects. Firstly, it plays a crucial role in environmental conservation. As the global community strives to lower its carbon footprint, transitioning to electric vehicles is a critical step in the right direction. However, the success of this transition hinges heavily on the availability of efficient charging infrastructure. By enhancing the efficiency and power density of EV chargers, this project contributes meaningfully to the broader objective of sustainable and environmentally friendly transportation. Secondly, the project pushes the boundaries of technological advancement in the realm of power electronics, particularly concerning PFC pre-regulators. This pioneering work not only propels the field forward but also opens up potential applications in diverse areas that require high-efficiency power conversion.
From a societal perspective, this research bears significant importance in two primary aspects. Firstly, it plays a crucial role in environmental conservation. As the global community strives to lower its carbon footprint, transitioning to electric vehicles is a critical step in the right direction. However, the success of this transition hinges heavily on the availability of efficient charging infrastructure. By enhancing the efficiency and power density of EV chargers, this project contributes meaningfully to the broader objective of sustainable and environmentally friendly transportation. Secondly, the project pushes the boundaries of technological advancement in the realm of power electronics, particularly concerning PFC pre-regulators. This pioneering work not only propels the field forward but also opens up potential applications in diverse areas that require high-efficiency power conversion.
The project commenced with an extensive literature review, aiming to understand current state-of-the-art power converter topologies. Potential topologies were explored, and the most promising ones were identified based on various parameters such as efficiency, inductor size, cost, and control challenges. Based on these findings, the focus was directed towards Continuous Conduction Mode (CCM) topologies with a goal to design and optimize PFC stage. To push the switching frequency higher, a new soft-switching TP PFC topology was invented. This topology offers substantial advantages over conventional ones as it allows the converter to maintain simple control at a fixed switching frequency. The design procedures were thoroughly analyzed to demonstrate the potential of this innovative topology. Alongside the PFC converter, we've also concentrated on the development of a DC/DC converter stage for a 48V system in light EV chargers.
Next, system-level optimization was undertaken. Accurate analytical models for major power converter components were developed and a system-level optimization approach was implemented to enhance converter designs. Significant effort was put into setting up a simple equation-based relationship for GaN field-effect-transistors (FETs). This tool streamlined the design and selection process, saving time and resources. In addition, a novel magnetics optimization tool for gapped-magnetics was proposed.
The next phase involved optimizing the EMI filter, which includes creating 3D models for X-capacitors and common-mode chokes and studying the impact of mutual couplings on attenuation. As the project advanced, a focus was placed on magnetics integration. A planar winding model was established, and finite element analysis (FEA) tools were utilized to evaluate the current crowding caused by field strength and fringing losses. This phase of research led to the introduction of an asymmetrical interleaving method that increases power density.
Finally, prototyping and application tests were conducted. This phase was pivotal in validating the theoretical and simulation work carried out in the previous stages. Two main groups of prototypes were built: wound-core designs and planar magnetics. These prototypes demonstrated the effectiveness of the optimization tool in creating high-performance, high-power-density converters that outperform existing designs. Throughout the project, dissemination activities including academic publications, conference presentations, workshops, and digital outreach ensured the visibility and impact of the project.
Next, system-level optimization was undertaken. Accurate analytical models for major power converter components were developed and a system-level optimization approach was implemented to enhance converter designs. Significant effort was put into setting up a simple equation-based relationship for GaN field-effect-transistors (FETs). This tool streamlined the design and selection process, saving time and resources. In addition, a novel magnetics optimization tool for gapped-magnetics was proposed.
The next phase involved optimizing the EMI filter, which includes creating 3D models for X-capacitors and common-mode chokes and studying the impact of mutual couplings on attenuation. As the project advanced, a focus was placed on magnetics integration. A planar winding model was established, and finite element analysis (FEA) tools were utilized to evaluate the current crowding caused by field strength and fringing losses. This phase of research led to the introduction of an asymmetrical interleaving method that increases power density.
Finally, prototyping and application tests were conducted. This phase was pivotal in validating the theoretical and simulation work carried out in the previous stages. Two main groups of prototypes were built: wound-core designs and planar magnetics. These prototypes demonstrated the effectiveness of the optimization tool in creating high-performance, high-power-density converters that outperform existing designs. Throughout the project, dissemination activities including academic publications, conference presentations, workshops, and digital outreach ensured the visibility and impact of the project.
Through this project, significant strides have been made beyond the state of the art in power electronics systems for EV charging. The research and development have focused on drastically miniaturizing high-power electronics systems for 48 V light EV chargers while enhancing efficiency and performance. The target is not just a technological advancement, but also a substantial contribution to the larger societal goal of promoting sustainable energy practices and reducing carbon emissions. The project's key focus areas include improving converter topologies, control schemes, and optimization techniques, with the objective of elevating the performance of power converters. As such, the project anticipates delivering faster, more reliable, and more efficient charging solutions for EVs. These advancements will enhance the charging experience for EV owners and facilitate the more widespread adoption of electric vehicles.
The power electronic structure at the core of the research comprises a PFC converter and a DC/DC stage. The research has resulted in the invention of a soft-switching TP PFC converter with interleaving legs, contributing to significant advancements in power electronics technology. The project's experimental prototypes have demonstrated impressive power density and efficiency results. For instance, the two-phase interleaved soft-switched TP PFC converter achieved 62 W/in³ and 98.72% efficiency at full load, while the 4-level TP PFC reached 67 W/in³ and 99.2% efficiency. The optimized LLC prototype also showed promising results, with a power density of 45 W/in³ and a peak efficiency of 98.2%.
These achievements have laid the groundwork for extending the developed models to very high-frequency designs. New converter configurations, such as the two-phase interleaved 7-level TP PFC and 3-phase LLC converters, have been analyzed, both utilizing planar magnetics. These high-frequency designs have the potential to further increase power density and efficiency, paving the way for even more compact and advanced power electronics systems. In particular, the 3-phase LLC design with planar magnetics employs an innovative approach known as asymmetrical interleaving. This technique integrates the resonant inductance into the transformer, enabling highly miniaturized designs. All the necessary analyses on the inductors have been conducted, and proof-of-concept prototypes are being manufactured. The 7-Level interleaved GaN-based TP PFC can deliver 3700 watts of power in a compact 255 x 71 x 20 mm form factor using planar magnetics, achieving a power density of 167 W/in³, which significantly exceeds the target of 85 W/in³. When combined with an innovative three-phase LLC with integrated magnetics, the total power density of the system reaches 84 W/in³.
The power electronic structure at the core of the research comprises a PFC converter and a DC/DC stage. The research has resulted in the invention of a soft-switching TP PFC converter with interleaving legs, contributing to significant advancements in power electronics technology. The project's experimental prototypes have demonstrated impressive power density and efficiency results. For instance, the two-phase interleaved soft-switched TP PFC converter achieved 62 W/in³ and 98.72% efficiency at full load, while the 4-level TP PFC reached 67 W/in³ and 99.2% efficiency. The optimized LLC prototype also showed promising results, with a power density of 45 W/in³ and a peak efficiency of 98.2%.
These achievements have laid the groundwork for extending the developed models to very high-frequency designs. New converter configurations, such as the two-phase interleaved 7-level TP PFC and 3-phase LLC converters, have been analyzed, both utilizing planar magnetics. These high-frequency designs have the potential to further increase power density and efficiency, paving the way for even more compact and advanced power electronics systems. In particular, the 3-phase LLC design with planar magnetics employs an innovative approach known as asymmetrical interleaving. This technique integrates the resonant inductance into the transformer, enabling highly miniaturized designs. All the necessary analyses on the inductors have been conducted, and proof-of-concept prototypes are being manufactured. The 7-Level interleaved GaN-based TP PFC can deliver 3700 watts of power in a compact 255 x 71 x 20 mm form factor using planar magnetics, achieving a power density of 167 W/in³, which significantly exceeds the target of 85 W/in³. When combined with an innovative three-phase LLC with integrated magnetics, the total power density of the system reaches 84 W/in³.