Showing papers by "Juan Carlos Balda published in 2019"
17 Mar 2019
TL;DR: This work designs and builds a high-power-density traction inverter using commercial off-the-shelf (COTS) parts, and possibilities for volume reduction to achieve 25 kW/l are evaluated revealing the challenges to achieve even higher power densities using COTS technologies.
Abstract: The requirements on volumetric density of power electronic converters in electric vehicles are increasing, since more space is needed for electronic systems and passenger capacity. The U.S. Department of Energy (DOE) has set the 2020 target for vehicular power electronic systems as 13.4 kW/l. Achieving high power density using commercial off-the-shelf (COTS) parts is challenging because these components have various form factors leading to unused spaces, as well as cooling and airflow issues. In this work, a high-power-density traction inverter, rated at 50-kW with the peak power at 74-kW, is designed and built using all COTS components. The system is tested under resistive-inductive loads and a dynamometer-based driving schedule. A power density of 13.64 kW/l was accomplished and possibilities for volume reduction to achieve 25 kW/l are evaluated revealing the challenges to achieve even higher power densities using COTS technologies.
10 citations
01 Mar 2019
TL;DR: This paper introduces a hybrid snubber that attempts to solve dynamic and static voltage balancing issues as well as providing power for each switch from the bus to which it is connected.
Abstract: With SiC devices enabling much higher voltage converters with lower complexity, a modular switching position that eliminates some of the issues with medium-voltage converters (e.g., high isolation voltages and dv/dt’s) would be valuable. Full modularity requires the ability to stack any arbitrary number of units in series. A requirement for this functionality is voltage balancing between all series switches. This paper introduces a hybrid snubber that attempts to solve these dynamic and static voltage balancing issues as well as providing power for each switch from the bus to which it is connected. A method for determining the required component values is developed and simulations are used to test the viability of the circuit. Then, a 600 V prototype is constructed using two MOSFETs in series to confirm the functionality of the snubber.
5 citations
TL;DR: A novel control strategy for NSS considering the effects of parameter uncertainties is proposed, which can estimate and adapt the control trajectories in a minimum number of switching cycles to obtain excellent performances even under extreme parameter uncertainties.
Abstract: The derivation and implementation of the natural switching surfaces (NSS) considering certain parametric uncertainties for a flyback converter operating in the boundary conduction mode is the main focus of this paper. The NSS with nominal parameters presents many benefits for the control of nonlinear systems; for example, fast transient response under load-changing conditions. However, the performance worsens considerably when the converter actual parameters are different from the ones used in the design process. Therefore, a novel control strategy for NSS considering the effects of parameter uncertainties is proposed. This control law can estimate and adapt the control trajectories in a minimum number of switching cycles to obtain excellent performances even under extreme parameter uncertainties. The analytical derivation of the proposed adaptive switching surfaces is presented together with simulations and experimental results showing adequate performance under different tests, including comparisons with a standard PI controller.
4 citations
01 Sep 2019
TL;DR: The use of solid-state transformers to feed an electric arc furnace is carried out and the definition of the level of wear according to the overload conditions as well as the development of a methodology to calculate the wear and reliability of the equipment are developed.
Abstract: In this paper the feasibility study of the use of solid-state transformers to feed an electric arc furnace is carried out. The proposal is based on the specifications of an electric arc furnace transformer of 28kVA installed in a local steel manufacturing facility. Thermal and chargeability tests are carried out on solid state transformers in order to determine their performance and the level of deterioration caused by thermal stresses to which they could be subject in electric arc furnace installations. This will allow the definition of the level of wear according to the overload conditions as well as the development of a methodology to calculate the wear and reliability of the equipment, and thus be able to assess its performance compared with conventional oil-filled transformers.
01 May 2019
TL;DR: The main objective of this research work is to develop a new low-cost isolated three-level ac-dc power converter topology that is suitable for applications having high input ac voltages and high output currents; for example, hybrid (ac-dc) microgrids or offshore wind farms.
Abstract: The main objective of this research work is to develop a new low-cost isolated three-level ac-dc power converter topology that is suitable for applications having high input ac voltages and high output currents; for example, hybrid (ac-dc) microgrids or offshore wind farms. Existing three-level converter topologies convert ac power to dc power while maintaining requirements set by international standards for power conversion. These types of converters have significant conduction losses due to high currents in the low-voltage side and high costs, particularly when using several devices in series or in parallel to achieve high-voltage and high-power levels. The proposed topology replaces the conventional three-level converters in the low-voltage side by only two controlled devices and four diodes while still maintaining the basic functionality of a three-level converter. Simulation results for a 87.5-kW case study and experimental results on a 250-W scale-down prototype demonstrate the feasibility of the proposed ideas.
17 Mar 2019
TL;DR: A numerical method is proposed to estimate the minimum required dc-link capacitor value and a novel control strategy, which integrates the current loop with an energy loop, is proposed for the interleaved boost dc-dc converter supplying a traction inverter.
Abstract: There is a growing demand for high-power-density powertrains in electric and hybrid vehicles to increase the space available for passengers and/or other high-technology electronics. The dc-link capacitor bank occupies a large volume in traction inverters, so minimizing the needed capacitance reduces system volume. Thus, in this paper a numerical method is proposed to estimate the minimum required dc-link capacitor value. Then a novel control strategy, which integrates the current loop with an energy loop, is proposed for the interleaved boost dc-dc converter supplying a traction inverter. The impacts that the inductor value and control settling time of the dc-dc converter have upon the system stability are analyzed. The feasibility and effectiveness of the proposed controller are validated through experimental studies using a three-phase boost-interleaved dc-dc converter connected to a three-phase inverter.