Design Approaches to Enhance Power Density in Power Converters for Traction Applications

This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best accomplish volume and thermal constraints. This work is coupled with a control strategy for the DC-DC converter whereby a variable-frequency Discontinuous Conduction Mode (DCM) control is used to further reduce the required values of the passive components, to provide an increase in power density and a large improvement of low-power-level efficiency, experimentally demonstrated at full power through an 80 kW Interleaved Boost Converter. Integration of this enhanced DC-DC stage to the DC-AC stage requires a DC-Link capacitor, which hinders achieving power density targets. Increasing the switching frequency is an established method of reducing the size of passives. However, it is the RMS current sizing requirements that diminishes any gains achieved by raising the switching frequency. A synchronous carrier phase shift-based control algorithm, that aligns the output current of the boost stage with the input current of an inverter, is proposed to reduce the RMS current in the DC-Link capacitor by up to 25% and an average 20% smaller capacitor volume. Lastly, a new electrothermal platform based on paralleled discrete devices is presented for a 50 kW traction inverter. Embedded capacitors within the vacant volume of the hybrid material thermal management structure enables higher power density (155 kW/L) and significantly reduces cost

Design Approaches to Enhance Power Density in Power Converters for Traction Applications

This dissertation presents a design strategy to increase the power density for automotive Power Conversion Units (PCUs) consisting of DC-DC and DC-AC stages. The strategy significantly improves the volumetric power density, as evident by a proposed PCU constructed and tested having 55.6 kW/L, representing an 11.2 % improvement on the Department of Energy’s 2025 goal of 50 kW/L for the same power electronics architecture. The dissertation begins with a custom magnetic design procedure, based on optimization of a predetermined C-core geometrical relationship and custom Litz wire. It accounts for electrical and thermal tradeoffs to produce a magnetic structure to best accomplish volume and thermal constraints. This work is coupled with a control strategy for the DC-DC converter whereby a variable-frequency Discontinuous Conduction Mode (DCM) control is used to further reduce the required values of the passive components, to provide an increase in power density and a large improvement of low-power-level efficiency, experimentally demonstrated at full power through an 80 kW Interleaved Boost Converter. Integration of this enhanced DC-DC stage to the DC-AC stage requires a DC-Link capacitor, which hinders achieving power density targets. Increasing the switching frequency is an established method of reducing the size of passives. However, it is the RMS current sizing requirements that diminishes any gains achieved by raising the switching frequency. A synchronous carrier phase shift-based control algorithm, that aligns the output current of the boost stage with the input current of an inverter, is proposed to reduce the RMS current in the DC-Link capacitor by up to 25% and an average 20% smaller capacitor volume. Lastly, a new electrothermal platform based on paralleled discrete devices is presented for a 50 kW traction inverter. Embedded capacitors within the vacant volume of the hybrid material thermal management structure enables higher power density (155 kW/L) and significantly reduces cost

DC-Side Soft-Switching Inverter with Modified Space-Vector Modulation Scheme

Three-phase soft-switching inverters are promising in order to reduce the losses in the switching devices and to reduce the electromagnetic interference produced by severe di/dt and dv/dt, which enables the operation of the inverter at higher switching frequency. This work proposes a DC-side three-phase zero-voltage soft-switching inverter topology that can be sub-categorized under actively clamped resonant dc-link topologies. Moreover, a modified space-vector modulation scheme is proposed, such that all the devices operate under zero-voltage switching condition. Compared to other similar dc-link soft-switching topologies, the proposed topology does not require feedback from the inverter output currents to achieve soft-switching operation. Unlike conventional space-vector modulation techniques, the proposed modified space-vector modulation does not require to turn-on the top and/or the bottom three switches of the two-level inverter at the same time to implement the zero vectors, which allows a reduction of the effective commutating time of the two-level inverter switches by one-third, during a grid voltage cycle. The auxiliary capacitor is only charged to a fraction of the dc bus voltage. Simulation and experimental results on a 10-kW and 100-kHz switching frequency lab-scale prototype are presented to demonstrate the validity and effectiveness of the proposed zero-voltage switching topology and modulation scheme on reducing the switching losses and electromagnetic interference.Fil: Fantino, Roberto Armin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Shamar, Christian. University of Arkansas; Estados UnidosFil: Balda, Juan Carlos. University of Arkansas; Estados UnidosFil: Asim, Solangi. University of Arkansas; Estados Unido

Inductor Encapsulation-Based Thermal Management Enabling Increased Power Density

Inductors occupy significant volume in dc-dc converters where power density is an important figure of merit. This research work addresses an improved design of a power-dense nanocrystalline-based inductor employing potting materials with high thermal conductivity. Contrary to traditional inductor design methods which require larger volumes to accommodate for temperature rise limits, this work presents an analytical framework to decrease the inductor volume through encapsulation. Particularly, it analyzes the effectiveness of employing a hybrid potting material, through experimental investigation of various filler compositions as compared to the classical silicone gel-based materials. Experimental evidence verifying the theoretically designed method is presented in this work.Fil: Christian, Shamar. University of Arkansas for Medical Sciences; Estados UnidosFil: Fantino, Roberto Armin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Amir Gomez, Roderick. University of Arkansas for Medical Sciences; Estados UnidosFil: Balda, Juan Carlos. University of Arkansas for Medical Sciences; Estados Unidos13th International Symposium on Power Electronics for Distributed Generation SystemsKielAlemaniaInstitute of Electrical and Electronics Engineer

A 150-kW 99% Efficient All-Silicon-Carbide Triple-Active-Bridge Converter for Solar-Plus-Storage Systems

Solar-plus-storage systems could effectively mitigate the uncertainties of the photovoltaic (PV) generation and improve system reliability by adding an integrated battery energy storage system. As a three-port bidirectional isolated dc-dc converter with soft-switching capability, the triple-active-bridge (TAB) converter inherently matches the requirements of the solar-plus-storage system. However, challenges still remain in the TAB converter design to further improve system efficiency. In this article, the detailed design, implementation, and demonstration for a silicon carbide (SiC) 150-kW TAB converter are presented. Starting from a brief review of the TAB converter, the modulation scheme, power characteristics, and soft-switching region are analyzed. Then, the detailed design of the H-bridge converter building block is given. To improve the system efficiency, a comprehensive characterization of the SiC gate driver with various external gate resistances is performed to address tradeoffs between switching loss and voltage overshoot during transients, as well as the thermal performance of the H-bridge building block. In addition, the design and characterization of the 20-kHz three-port transformer are also given. Comprehensive experimental studies are conducted on a full-power prototype to verify the proposed design. With a measured 99.1% peak efficiency, the proposed TAB converter can fulfill the requirements for solar-plus-storage applications.Fil: Wu, Yuheng. University of Arkansas; ArgentinaFil: Mahmud, Mohammad Hazzaz. University of Arkansas; ArgentinaFil: Christian, Shamar. University of Arkansas; ArgentinaFil: Fantino, Roberto Armin. University of Arkansas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gomez, Roderick Amir. University of Arkansas; ArgentinaFil: Zhao, Yue. University of Arkansas; ArgentinaFil: Balda, Juan Carlos. University of Arkansas; Argentin

Etching Process to Reduce Interlamination Short Circuits and Core Loss Comparison for Tape-Wound Cut Cores

Soft-magnetic ribbon-based materials have been gaining popularity as their properties yield better efficiencies and power densities. Nevertheless, magnetic designs with these materials present a major shortcoming in the manufacturing process of tape-wound cut cores. Thus, this paper focuses on the critical issue of ribbon-based soft-magnetic cut-cores due to short-circuited layers along the cross-sectional area resulting from the cutting process. An etching process is proposed to overcome the interlamination short circuits of the magnetic cores. A microscopic view of the cross-sectional area demonstrates the effectiveness of the etching process. Furthermore, two identical experimental medium-frequency transformers are built to study and compare the effects of the core etching on the transformer parameters. Open- and short-circuit impedance responses, and core loss characterization over frequency and flux density are presented before and after the etching process to establish the proper process to handle these tape-wound cut cores.Fil: Gomez, Roderick A.. University of Arkansas for Medical Sciences; Estados UnidosFil: Christian, Shamar F.. University of Arkansas for Medical Sciences; Estados UnidosFil: Oggier, Germán G.. Universidad Nacional de Río Cuarto; ArgentinaFil: Fantino, Roberto Armin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Balda, Juan C.. University of Arkansas for Medical Sciences; Estados UnidosFil: Zhao, Yue. University of Arkansas for Medical Sciences; Estados Unidos13th International Symposium on Power Electronics for Distributed Generation SystemsKielAlemaniaInstitute of Electrical and Electronics Engineer