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 Three-Level Full-Bridge Zero-Voltage Zero-Current Switching Converter With a Simplified Switching Scheme

Abstract: Multilevel DC-DC converters making use of high-frequency transformers are suitable for integration in solid-state solutions for applications in electric power distribution systems. This paper presents a simplified switching scheme for three-level full-bridge DC-DC converters that enables zero-voltage and zero-current switching of all the main power devices. It describes the main operational modes and design equations of the converter as well as provides simulation and experimental results to demonstrate the feasibility of the proposed ideas.

High-temperature silicon carbide and silicon on insulator based integrated power modules

Abstract: This paper presents the challenges and results of fabricating a high temperature silicon carbide based integrated power module. The gate driver for the module was integrated into the power package and is rated for an ambient temperature of 250 °C. The power module was tested up to 300 V bus voltage, 160 A peak current, and 250 °C junction temperature.

Measurements of neutral currents and voltages on a distribution feeder

Abstract: Neutral currents flow in four-wire distribution systems due to linear load unbalances and triplen harmonics associated with mainly the magnetizing currents of (distribution) transformers. It is known that high levels of neutral currents can lead to overloaded/burned neutral conductors, common-mode noise problems, derating of transformers and/or excessive voltage distortion. The proliferation of nonlinear loads which inject harmonic currents into the distribution system has brought more attention upon the levels of neutral currents and voltages found in distribution systems. To this end, this paper evaluates measurements taken on the neutral conductors of a distribution feeder at two different sites. The analysis of the measurements focuses on the magnitudes of the triplen-harmonic currents and voltages relative to their corresponding phase RMS values in order to separate the impact on the neutral conductors of nonlinear loads and linear load unbalances.

Placement of energy storage coordinated with smart PV inverters

Abstract: Energy storage (ES) is increasing used in electrical transmission and distribution systems because it can perform many functions. These include peak shaving, voltage regulation, frequency regulation, spinning reserve, and aiding integration of renewable generation by mitigating the effects of intermittency. This work focuses on the usage of energy storage for peak shaving and voltage regulation on a distribution system having a high penetration of photovoltaic (PV) generation. The PV stations considered make use of smart PV inverters as proposed by the Electric Power Research Institute (EPRI). These inverters assist the energy storage with voltage regulation. Additionally, the proposed method includes support for varying energy storage unit (ESU) sizes, non-radial distribution systems, and reverse power flow, both real and reactive. The method is applied to the worst-case voltage regulation scenario. The impact of the placement and voltage regulation on the profitability of energy storage is assessed. This is accomplished by adding voltage regulation as a constraint to the problem scheduling energy storage in order to maximize profit. Applying the method shows that the best place to put an ESU is near the end of a feeder. Validation of the method shows that it does not impact the ability of ES to be scheduled in order to maximize economic benefits with time-ofuse pricing.

Selection of converter topologies for distributed energy resources

Abstract: Distributed energy resources (DER) are becoming increasingly common on the electrical grid. Depending on the operating conditions of the DER, which depend on the application, different topologies need to be selected in order to achieve the maximum efficiency of each DER. Complicating the selection is the fact that operating conditions vary over time. For example, the voltage and current drawn from a PV panel varies over the course of a day. To calculate the overall efficiency, the efficiency of a topology at each operating point and the amount of time spent at that operating point must be considered. This work extends existing analytical methods for loss calculations by taking this into account. The specific DER applications considered are a three-phase ultracapacitor energy storage unit (UC-ESU), battery energy storage unit (B-ESU), and photovoltaic array (PV). This work determines for each application if an inverter-only (single-stage) or an inverter plus boost converter (double-stage) topology is more efficient. The results show that a single-stage topology is better for the B-ESU and PV, while the double-stage topology is better for the UC-ESU. The method is applicable to other DER types, including wind turbines, micro-hydro generators, variable-speed gensets, and microturbines.

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.