Browsing by Author "Cuzmar Leiva, Rodrigo Hernán"

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    Phase-Shifted Model Predictive Control to Achieve Power Balance of CHB Converters for Large-Scale Photovoltaic Integration
    (2020) Cuzmar Leiva, Rodrigo Hernán; Pereda Torres, Javier Eduardo; Aguilera, Ricardo P.
    Cascaded H-Bridge (CHB) converters are attractive candidates for next generation photovoltaic (PV) inverters. CHB converters present a reduced voltage stress per power switch and a high modularity. Therefore, the plant can be divided in several PV strings that can be connected to each H-bridge cell. However, due to variability on solar irradiance conditions, each PV string may present different maximum available power levels, which difficult the overall converter operation. To address this issue, this paper presents a model predictive control (MPC) strategy, which works along with a phase-shifted PWM (PS-PWM) stage; hence its name phase-shifted MPC (PS-MPC). The novelty of this proposal is the way both inter-bridge and inter-phase power imbalance are directly considered into the optimal control problem by a suitable system reference design. Thus, the inter-phase imbalance power is tackled by enforcing the converter to operate with a proper zero-sequence voltage component. Then, by exploiting the PS-PWM working principle, PS-MPC is able to handle each H-bridge cell independently. This allows the predictive controller to also deal with an inter-bridge power imbalance using the same control structure. Experimental results on a 3 kW prototype are provided to verify the effectiveness of the proposed PS-MPC strategy.
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    Predictive Optimal Variable-Angle PS-PWM Strategy for Cascaded H-Bridge Converters
    (2024) Poblete Durruty, Pablo Martín; Gajardo Rojas, José Ignacio; Cuzmar Leiva, Rodrigo Hernán; Aguilera, Ricardo P.; Pereda Torres, Javier Eduardo; Lu, Dylan; Márquez, Abraham M.
    Cascaded H-bridge (CHB) converters are an attractive candidate for numerous applications, including static synchronous compensators and next-generation photovoltaic and battery energy storage inverters. Due to its simplicity, scalability, and excellent harmonic performance, phase-shifted pulsewidth modulation (PS-PWM) is one of the preferred modulation strategies for CHB converters. However, the latter advantage might be drastically affected when an unbalanced operation in the H-bridge cells is required, e.g., setting different dc-voltage levels and/or ac-voltage references among cells. This work proposes a predictive optimal variable angle PS-PWM (OVA-PS-PWM) strategy for CHB converters. The proposed OVA-PS-PWM introduces a bilinear dynamic model that describes the impact of the phase-shift angles (PS-angles) over the CHB output voltage harmonics. This model is then employed to formulate an optimal control problem that minimizes the output voltage harmonic distortion. An analytical optimal solution for a PS-angle update rule that applies to CHB converters of any number of cells is derived. As a result, the proposed OVA-PS-PWM updates each PS-angle at every sampling instant, significantly improving the harmonic content of the CHB output voltage even under severely unbalanced operation scenarios. Experimental results are provided with a CHB converter with nine cells to verify the effectiveness of the proposed optimal modulation strategy.
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    Sequential Phase-Shifted Model Predictive Control for a Multilevel Converter with Integrated Battery Energy Storage
    (2020) Neira, Sebastián; Poblete, Pablo; Cuzmar Leiva, Rodrigo Hernán; Pereda Torres, Javier Eduardo; Aguilera, Ricardo P.
    Cascaded converters have risen as a suitable solution for the connection of Utility-scale Battery Energy Storage Systems (BESS) to the grid. These converters allow to split the battery array into the power modules, reducing the total series-connected battery cells and improving the reliability of the system. Different types of modules have been proposed to integrate the batteries in the converter. The three-port full-bridge module connects the batteries through a second deport decoupled from the harmful low-frequency oscillations and current peaks. However, the multi-variable controller required to manage the power interaction between the battery and the grid presents a challenge in terms of computational burden and scalability. This work proposes the use of the Sequential Phase-Shifted Model Predictive Control (PS-MPC) in a multilevel BESS implementation using three-port full-bridge modules. The proposed controller outperforms a standard FCS-MPC, as it obtains the optimal duty cycles for the operation of the converter with the same fast dynamic response, but also with the fixed spectrum of the PS-PWM and low computational burden, which facilitates its scalability to multilevel BESS with a large number of cells. Simulation results show the ability of the system to exchange different amounts of power with the grid, ensuring the best battery operational conditions
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    Sequential Phase-Shifted Model Predictive Control for a Multilevel Converter with Integrated Battery Energy Storage
    (IEEE, 2020) Neira Castillo, Sebastian Felipe; Poblete Durruty, Pablo Martín; Cuzmar Leiva, Rodrigo Hernán; Pereda Torres, Javier Eduardo; Aguiler, R. P.
    Cascaded converters have risen as a suitable solution for the connection of Utility-scale Battery Energy Storage Systems (BESS) to the grid. These converters allow to split the battery array into the power modules, reducing the total series-connected battery cells and improving the reliability of the system. Different types of modules have been proposed to integrate the batteries in the converter. The three-port full-bridge module connects the batteries through a second deport decoupled from the harmful low-frequency oscillations and current peaks. However, the multi-variable controller required to manage the power interaction between the battery and the grid presents a challenge in terms of computational burden and scalability. This work proposes the use of the Sequential Phase-Shifted Model Predictive Control (PS-MPC) in a multilevel BESS implementation using three-port full-bridge modules. The proposed controller outperforms a standard FCS-MPC, as it obtains the optimal duty cycles for the operation of the converter with the same fast dynamic response, but also with the fixed spectrum of the PS-PWM and low computational burden, which facilitates its scalability to multilevel BESS with a large number of cells. Simulation results show the ability of the system to exchange different amounts of power with the grid, ensuring the best battery operational conditions.
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    Sequential Phase-Shifted Model Predictive Control for a Multilevel Converter with Integrated Battery Energy Storage
    (2020) Neira, Sebastián; Poblete, Pablo; Cuzmar Leiva, Rodrigo Hernán; Pereda Torres, Javier Eduardo