Browsing by Author "Rojas, Félix"

Now showing 1 - 12 of 12
  • Thumbnail Image
    Item
    A Design Methodology of Multiresonant Controllers for High Performance 400 Hz Ground Power Units
    (2019) Rojas, Félix; Cárdenas, Roberto; Clare, Jon; Díaz, Matías; Pereda Torres, Javier Eduardo; Kennel, Ralph
  • No Thumbnail Available
    Item
    Asymmetrical Triangular Current Mode (ATCM) for Bidirectional High Step Ratio Modular Multilevel Dc–Dc Converter
    (IEEE, 2020) Pineda Fornerod, Cristian Andrés; Pereda Torres, Javier Eduardo; Rojas, Félix; Cerda, Carlos; Zhang, Xiaotian; Watson, Alan J.
    Direct current (Dc) networks have proven advantages in high voltage direct current (HVDC) transmission systems, and now they are expanding to medium- and low-voltage distribution networks. One of the major challenges is to develop reliable dc-dc voltage transformation achieving high efficiency and performance, especially at high voltage and high step ratio. New resonant modular multilevel topologies have arisen as an alternative, mainly because of advantages such as optional use of transformers, natural voltage balance, simple control, and soft-switching capability. However, this type of operation generates a high peak current, does not allow control of power flow in all power range, and has a limited range of voltage variation. This article proposes an asymmetrical triangular current mode applied to high step ratio modular multilevel dc-dc converters. The proposed modulation increases the efficiency and achieves bidirectional control of the power, soft-switching, and a natural balance of the voltage in the cell capacitors. The experimental results show the bidirectional operation and the capacitor voltage balance of the converter under different operating conditions with higher efficiency (97.72%) and lower peak current compared to previous reports of this topology using resonant operation.
  • Thumbnail Image
    Item
    Dynamic DC-Link Voltage Control of Back to Back Modular Multilevel Converter for Drive Applications
    (IEEE, 2019) Lillo, Jonathan; Rojas, Félix; Verdugo, Diego; Dí­az, Matias; Pereda Torres, Javier Eduardo; Gatica, Gustavo; Espinoza, Mauricio
    In this work a dynamic control of the dc-link voltage in a hybrid Back-to-Back (BtB) Modular Multilevel Converter for medium-voltage drive applications is presented. The proposed control scheme relates the speed of the machine with the dc-link voltage magnitude to reduce the large circulating currents and common-mode voltage of the converter when the machine operates at low speed. Simulation results, performed in the software PLECS, validate the model of the BtB converter and the proposed control scheme, reducing circulating currents and common mode voltage in almost 70% and 60% respectively, when the machine operates at very low speed.
  • Thumbnail Image
    Item
    Inductor design for a High performance DC-DC Modular Multilevel Converter
    (IEEE, 2019) Cerda, Carlos; Rojas, Félix; Cristian Andres, Pineda Fornerod; Pereda Torres, Javier Eduardo; Diaz, Matias; Salgado, Jordan; Droguett, Gabriel; Valdés, Darío; Gatica, Gustavo
    In this paper is presented a simple method to design an inductor for high performance on a DC-DC Modular Multilevel Converter(MMC). This element is one of the main limitations for a proper fulfilment. A high-frequency inductor for high power applications is a key element to achieve high efficiency in such type of converters. The theoretical design of the inductor is compared with an experimental prototype, which is then implemented in a high-power DC-DC converter. Experimental results validate the accuracy of the theoretical design and the improvements in the efficiency of the overall DC-DC high power converter.
  • Thumbnail Image
    Item
    New dual H-bridge converter for continuous space vector modulation
    (2019) Durán Godoy, Tomás Antonio; Neira, Sebastián; Pereda Torres, Javier Eduardo; Rojas, Félix
    Multilevel converters are a significant improvement in the DC-AC conversion technology, reaching higher power quality in medium-voltage applications and using standard semiconductors in a smarter way than conventional converters, without necessarily increasing the cost. However, multilevel technology remains discrete and its only way to reduce the overall total harmonic distortion leads on the generation of several discrete levels on the output voltage. Therefore, it is not possible to reduce the harmonic distortion to negligible values, unless a big number of semiconductors are used, which is not cost-effective for low-voltage applications, limiting the reliability of the system. This study proposes a new dual H-bridge inverter that generates a three-phase output voltage with negligible distortion using two variable DC-DC power sources and a new continuous space vector modulation. Simulation and experimental results show high-quality output voltages. The topology is simple and uses only 12 semiconductors, but it requires special attention in the variable DC voltage converters, which can limit the maximum output frequency. Therefore, the solution is suitable for low power applications that require high power quality using small filters or none filters at the AC side. The results were obtained and validated using an experimental laboratory prototype under different operating conditions.
  • No Thumbnail Available
    Item
    Optimal ZCS Modulation for BidirectionalHigh-Step-Ratio Modular Multilevel dc-dc Converter
    (2021) Pineda Fornerod, Cristian Andres; Pereda Torres, Javier Eduardo; Rojas, Félix; Droguett Olea, Gabriel; Burgos Mellado, Claudio; Watson, Alan J.
    Recent developments in dc powered technologies have increased interest in highly efficient dc-dc converters, especially at high voltage and high-step voltage ratios. Modular multilevel converters (MMCs) are an attractive alternative approach to this demand because they can manage medium and high dc voltages while using standard semiconductor devices with high efficiency if they employ soft-switching techniques. However, the latest soft-switching techniques require resonant circuits, limiting their operation. This paper proposes an optimal modulation technique for a high-step-ratio dc-dc MMC, which achieves minimal rms current and zero-current switching. The proposed optimization generates trapezoidal or triangular current to operate the converter over a wide output voltage and power range, while using a simple control scheme to regulate the output voltage and the voltage balance among the floating cell capacitors. The theoretical analysis has been verified with a laboratory-scaled prototype, demonstrating the effectiveness of the approach and excellent dynamical response.
  • Thumbnail Image
    Item
    Power Imbalance Analysis of Modular Multilevel Converter with Distributed Energy Systems
    (2024) Salvadores Viertel, Tomás; Pereda Torres, Javier Eduardo; Rojas, Félix
    The modular multilevel converter (MMC) can integrate distributed energy systems (DES), such as a battery energy storage system, to expand its functionalities and carry out multiple simultaneous tasks. However, a DES induces power imbalances within the MMC, which affects the operating currents and voltages of the converter. This phenomenon has been partially covered in recent works, but an analytical analysis has not yet been carried out to see the behavior and implications in different MMC-DES applications. This article introduces a novel analytical analysis of the power imbalances between MMC clusters. It pioneers the development of general equations and imbalance capability metrics, enabling the assessment of maximum currents and voltages supported by the MMC clusters. The developed tools allow the evaluation of any MMC-DES application regarding the current and voltage rating requirements of MMC clusters. The analysis shows that the MMC operating mode can substantially restrain or enlarge its imbalance capacity, affecting its suitability for different DES applications. While it needs around 33% current overrating in the worst imbalances, under some operating modes it can reach most imbalances without requiring current overrating. The ac compensation mode is much more capable of achieving imbalances than the dc compensation mode, reaching 88.37% and 16.74% of the imbalance points, respectively, without requiring any overrating.
  • No Thumbnail Available
    Item
    Three-Port Full-Bridge Bidirectional Converter for Hybrid DC/DC/AC Systems
    (IEEE, 2020) Neira Castillo, Sebastian Felipe; Pereda Torres, Javier Eduardo; Rojas, Félix
    Sustainable solutions such as renewable energies, distributed generation, energy storage, and electric vehicles require power conversion and advance control techniques. This process is usually done in two stages by more than one power converter, specially in hybrid systems, increasing power losses and costs. The configuration with two dc stages and one ac port is widely used in several applications, such as grid-connected photovoltaic inverters; fuel cells, hybrid and electric vehicles; and ac/dc microgrids. Thus, three-port topologies have been developed to operate such systems, most of them comprising multiple power processing stages for the connection of the different elements. This article proposes a three-port full-bridge converter with a single power processing stage for dc/dc/ac systems. The ac port can be single-phase or three-phase, using two legs like an H-bridge or three legs like the conventional three-phase inverter. In both configurations, each leg is used as an inverter and as a buck-boost converter at the same time. The converter is able to manage the power flow among three ports with just four or six switches through a multivariable control strategy. Simulation and experimental results show the capability of the converter to manage the interaction between a battery and a capacitor connected to the grid achieving a fast dynamic response, bidirectional capability in all ports and reduction of components.
  • No Thumbnail Available
    Item
    Three-Port Full-Bridge Cell for Multilevel Converters with Battery Energy Storage
    (IEEE, 2019) Neira Castillo, Sebastian Felipe; Pereda Torres, Javier Eduardo; Merlin, Michael; Rojas, Félix
    Utility-scale Battery Energy Storage Systems (BESS) have increased rapidly during the last years providing grid support for variable renewable energies, operating reserve, and any other possible ancillary service. BESS can be connected to the MV grid through conventional converters such as two-level or NPC, or through multilevel converters such as CHB or MMC. Multilevel converters do not require LV/MV transformer or ac filter, which increases the efficiency and reduces the footprint and cost. Different cell topologies for multilevel converters have been proposed in order to interface the batteries with the ac side, where the key performance indicators are the battery current peaks, number of semiconductors, footprint, efficiency and cost. This paper proposes a three-port full-bridge cell (TPC) to connect the battery in multilevel converters through a Model Predictive Control. This cell adds passive elements that decouple the battery from the cell capacitor, avoiding the battery current peaks, downsizing the cell capacitor and improving the footprint. Simulation and experimental results show that the power flow between batteries and the grid can be controlled keeping the cell capacitors balanced and ensuring the best battery treatment.
  • No Thumbnail Available
    Item
    Triangular Current Mode for High Step Ratio Modular Multilevel DC-DC Converter
    (IEEE, 2018) Pineda Fornerod, Cristian Andres; Pereda Torres, Javier Eduardo; Zhang, Xiaotang; Rojas, Félix
    DC networks have generated much interest in recent years, from transmission in high voltage to their use in distribution systems. One of the major challenges is to replace the high efficient and reliable ac transformer, especially at high voltage and step ratio. New resonant modular multilevel topologies have arisen as an alternative, mainly because of advantages such as optional use of transformers, natural voltage balance, simple control and soft-switching. However, this type of operation generates a high peak current, does not allow control of power flow in all power range and has a limited range of voltage variation. This paper proposes an asymmetrical triangular current mode applied in high step ratio Modular Multilevel dc-dc Converters that achieves bidirectional control of the power, soft-switching and a natural balance of the voltage in the capacitors. The simulation results show the bidirectional operation and the capacitor voltage balance of the converter under different operating conditions with high efficiency and low peak current compared to resonant mode. The proposal was tested in a down-scale prototype, confirming the operation principle.
  • Thumbnail Image
    Item
    Wave Energy Conversion: Overview and Control of a Permanent Magnet Linear Generator
    (IEEE, 2019) Herrera Valencia, Rodrigo Fernando; Pereda Torres, Javier Eduardo; Bravo Niño de Zepeda, Pablo Felipe; Rojas, Félix
    Renewable energies are growing fastly worldwide, especially solar and wind generation. However, the diversification of power sources is key to have more stable and resilient power systems. Marine energy has one of the highest potentials and most of the world population is near the sea. Wave energy is one of the most promising forms of marine energy, which is achieving commercial viability with bigger projects and more mature designs. However, the environment hostility and difficult access are still one of the main limitations of this technology. This paper presents the state-of-the-art of wave energy conversion (WEC), the power to take off (PTO) devices, and the specific challenges of the converters and generator drives. Finally, a field oriented control (FOC) with maximum power point tracking (MPPT) is proposed for a linear permanent magnet synchronous generator (PMSG). The simulation results show the proper control and the specific characteristics of these types of generation.
  • Thumbnail Image
    Item
    Zero-Current Switching (ZCS) for a High Step Ratio Modular Multilevel dc-dc Converter with wide voltage range operation
    (IEEE, 2020) Pineda, Fornerod, Cristian Andres; Pereda Torres, Javier Eduardo; Burgos Mellado, Claudio; Watson, Alan; Rojas, Félix
    The rise of new dc technologies is pushing the development of highly efficient dc-dc converters, especially at high voltage and high step ratio. Modular multilevel converters (MMCs) are an attractive alternative because they can manage medium and high dc voltages with standard semiconductor devices with high efficiency if they employ soft-switching techniques. However, the latest soft-switching techniques have been proposed for fixed voltage range, limiting their operation. This paper proposes a soft-switching modulation for the high step ratio Modular Multilevel dc-dc Converter in extended voltage range. The proposal achieves zero-current switching and regulates the voltage balance among the floating cell capacitors, while using a simple control scheme to regulate the output voltage. The theoretical analysis has been verified with full-scale simulations, demonstrating excellent dynamic response and reduced rms current.