Juan Carlos Balda

Bio: Juan Carlos Balda is an academic researcher from University of Arkansas. The author has contributed to research in topics: Power module & Converters. The author has an hindex of 29, co-authored 180 publications receiving 3468 citations. Previous affiliations of Juan Carlos Balda include Clemson University & University of Arkansas at Little Rock.

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

Abstract: Solar-plus-storage systems could effectively mitigate 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 match the requirements of the solar-plus-storage system. However, challenges still remain in the TAB converter design to further improve the system efficiency. In this paper, 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 for 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.

Investigation of low-voltage solid-state DC breaker configurations for DC microgrid applications

Abstract: Among current research issues of dc microgrids, short-circuit protection is very challenging because of the high rate of rise for the fault currents. Slow-acting electromechanical circuit breakers lead to system overdimensioning resulting in additional costs. Circuit breakers based on power semiconductor devices have the potential of fast interruption of fault currents. Unfortunately, the energy stored in parasitic inductors or system inductive components have the potential of resulting in overvoltage across the solid-state circuit breaker (SSCB). Metal oxide varistor (MOV), snubber circuits and freewheeling diodes are used to protect the semiconductor devices against overvoltage. Six configurations for a voltage clamp for a SSCB are analyzed in this paper when inductive components are present on the load sides. Finally, the experimental results verified that series connected diode and MOV clamping provides better overvoltage protection for the SSCB.

A PV dispersed generator: a power quality analysis within the IEEE 519

Abstract: It is envisaged that the use of environmentally clean photovoltaic (PV) dispersed generation will become more widespread in the near future due to advances in PV technology which will lead to cost reductions. This paper summarizes the results of a power quality study performed on a rural distribution feeder having a PV generator and nonlinear loads in order to understand the effects that inverter-interfaced PV dispersed generation have upon the quality of electric power. Different interpretations for the harmonic distortion limits set in the IEEE 519-1992 standard are considered. This paper also includes a statistical analysis of all measurements recorded with the help of two power quality monitors, an evaluation of the results from a connection/disconnection test, and harmonies simulation results.

Optimal battery chemistry, capacity selection, charge/discharge schedule, and lifetime of energy storage under time-of-use pricing

Abstract: Energy storage units (ESU) can reduce the cost of purchased electricity under time-of-use (TOU) pricing. To maximize the cost reduction, the chemistries, capacities, and charge/discharge schedules of the batteries used in the ESU must be selected appropriately. The batteries must have sufficient capacities to supply the energy demanded by the charge/discharge profiles and to meet the project lifetime. The ESU responds to a TOU price structure. The ESU output power is limited by the rating of the power electronic interface. The cost of the ESU is assumed to increase linearly with battery capacity. A method using linear optimization is developed that determines the battery chemistries, capacities, and charge/discharge schedules simultaneously. The method shows that the Li-Ion battery chemistry is the most cost effective technology due to its high efficiency and that an 11-year project lifetime is most profitable.

SiC JFET dc characteristics under extremely high ambient temperatures

Abstract: This paper reports on the measured dc characteristics of a SiC JFET device from room temperature up to 450°C in order to evaluate the device's capability for high-temperature operation. The authors packaged SiC JFET bare die into a dedicated high-temperature package to be able to perform experiments under extremely high ambient temperatures. The experimental results show that the device can operate at 450°C, which is impossible for conventional Si devices, but the current capability of the SiC JFET diminishes with rising temperatures. For example, the saturation current becomes 20% at 450°C with respect to the value at the room temperature.

A Survey of Wide Bandgap Power Semiconductor Devices

Abstract: Wide bandgap semiconductors show superior material properties enabling potential power device operation at higher temperatures, voltages, and switching speeds than current Si technology. As a result, a new generation of power devices is being developed for power converter applications in which traditional Si power devices show limited operation. The use of these new power semiconductor devices will allow both an important improvement in the performance of existing power converters and the development of new power converters, accounting for an increase in the efficiency of the electric energy transformations and a more rational use of the electric energy. At present, SiC and GaN are the more promising semiconductor materials for these new power devices as a consequence of their outstanding properties, commercial availability of starting material, and maturity of their technological processes. This paper presents a review of recent progresses in the development of SiC- and GaN-based power semiconductor devices together with an overall view of the state of the art of this new device generation.

Overview of Dual-Active-Bridge Isolated Bidirectional DC–DC Converter for High-Frequency-Link Power-Conversion System

Abstract: High-frequency-link (HFL) power conversion systems (PCSs) are attracting more and more attentions in academia and industry for high power density, reduced weight, and low noise without compromising efficiency, cost, and reliability. In HFL PCSs, dual-active-bridge (DAB) isolated bidirectional dc-dc converter (IBDC) serves as the core circuit. This paper gives an overview of DAB-IBDC for HFL PCSs. First, the research necessity and development history are introduced. Second, the research subjects about basic characterization, control strategy, soft-switching solution and variant, as well as hardware design and optimization are reviewed and analyzed. On this basis, several typical application schemes of DAB-IBDC for HPL PCSs are presented in a worldwide scope. Finally, design recommendations and future trends are presented. As the core circuit of HFL PCSs, DAB-IBDC has wide prospects. The large-scale practical application of DAB-IBDC for HFL PCSs is expected with the recent advances in solid-state semiconductors, magnetic and capacitive materials, and microelectronic technologies.

Step-Up DC–DC Converters: A Comprehensive Review of Voltage-Boosting Techniques, Topologies, and Applications

Abstract: DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques.

Energy Storage Systems for Transport and Grid Applications

Abstract: Energy storage systems (ESSs) are enabling technologies for well-established and new applications such as power peak shaving, electric vehicles, integration of renewable energies, etc. This paper presents a review of ESSs for transport and grid applications, covering several aspects as the storage technology, the main applications, and the power converters used to operate some of the energy storage technologies. Special attention is given to the different applications, providing a deep description of the system and addressing the most suitable storage technology. The main objective of this paper is to introduce the subject and to give an updated reference to nonspecialist, academic, and engineers in the field of power electronics.