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Frede Blaabjerg - One of the best experts on this subject based on the ideXlab platform.

  • high step up y source inverter with reduced dc Link Voltage spikes
    IEEE Transactions on Power Electronics, 2019
    Co-Authors: Zichao Zhou, Wei Wang, Dianguo Xu, Frede Blaabjerg
    Abstract:

    Impedance-source inverters using coupled inductors have been investigated as alternatives for providing high step-up Voltages. However, leakage inductances of the coupled inductors have commonly led to lower overall effectiveness, in addition to generating high dc-Link Voltage spikes. The latter raises Voltage stresses of switches, which in turn, may reduce the power levels of the inverters. A high step-up Y-source inverter has therefore been proposed in this paper to provide a high boost with a smooth dc-Link Voltage ensured by proper recycling of the leakage energy. These features have been verified by comparing simulation and experimental results of an existing Y-source and the proposed inverters. Factors compared are their respective boost ratios, Voltage stresses, current stresses, and dc-Link Voltage spikes.

  • impedance based analysis of dc Link Voltage dynamics in Voltage source converters
    IEEE Transactions on Power Electronics, 2019
    Co-Authors: Dapeng Lu, Xiongfei Wang, Frede Blaabjerg
    Abstract:

    This paper addresses the stability issues caused by the dc-Link Voltage control of grid-connected Voltage-source converters. An analytical impedance model is developed first for capturing the interactions between the dc-Link Voltage control and ac current control of converters, which enables to identify different stability impacts of the dc-Link Voltage control in the rectifier and inverter operation modes of converters. The impedance model is further transformed from the $dq$ -frame to the $\alpha \beta $ -frame, which allows characterizing the frequency-coupling effects of the dc-Link Voltage control dynamics. The impedance-based analysis reveals that the dc-Link Voltage control may cause low-frequency oscillations in the rectifier mode and high-frequency oscillations in the inverter mode. Case studies on the rectifier and inverter operation modes are presented, and subsequently validated by using time-domain simulations and experimental tests. The close correlations between the measured results and theoretical analysis demonstrate the effectiveness of the impedance model and stability analysis.

  • Influence of Reactive Power Flow on the DC-Link Voltage Control in Voltage-Source Converters
    2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
    Co-Authors: Dapeng Lu, Xiongfei Wang, Frede Blaabjerg
    Abstract:

    This paper analyzes the influence of reactive power flow on the dc-Link Voltage control in Voltage-source converters. The dc-Link Voltage and reactive power is coupled through the ac side filter based on the power balance. An analytical impedance model is further developed for characterizing the dynamics of the dc-Link Voltage control, which allows identifying the stability impacts under different reactive power. The impedance-based analysis reveals that the directions of reactive power flow, i.e. the inductive or capacitive reactive power, have reverse impacts on the stability of the dc-Link Voltage control under a weak grid condition. Case studies on the inductive and capacitive reactive power are carried out, and subsequently validated by using time-domain simulations and experimental tests. The results verify the effectiveness of the impedance model and the stability analysis.

  • Characterization of Proportional-Integral-Resonant Compensator for DC Link Voltage Control
    2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL), 2018
    Co-Authors: Seyed Fariborz Zarei, Mohammad Amin Ghasemi, Saeed Peyghami, Pooya Davari, Hossein Mokhtari, Frede Blaabjerg
    Abstract:

    Voltage unbalance and short circuits in distribution networks adversely affect the performance of grid-tied Voltage source inverters (VSIs). Consequently, the dc-Link Voltage ripple may significantly increase leading to operation of VSI in an unsatisfactory manner. Conventionally in order to maintain the negative sequence current under unbalanced conditions, low-pass/trap filter in the current control loop are required which significantly reduce the controller bandwidth. In order to minimize the dc-Link Voltage ripple without impairing the controller bandwidth, this paper investigates the design and performance of Proportional-Integral-Resonant (PIR) controller in improving the performance of the VSI under unbalanced condition. The proposed design methodology is validated through simulations and experimental results.

  • Link Voltage peak control of parallel resonant converter by control of the converter switching instant
    IEEE Transactions on Power Electronics, 1997
    Co-Authors: Stig Munk-nielsen, Frede Blaabjerg, J.k. Pedersen
    Abstract:

    This paper describes a new control strategy of the parallel resonant DC Link converter called Voltage peak control (VPC). VPC limits the Link Voltage to twice the DC Link Voltage. The strategy eliminates the need of additional power electronic components that clamp the Link Voltage. The operation of the resonant Link is described highlighting the factors that influence on the Link Voltage peak. The paper describes how control of the Link Voltage peak is possible by appropriate timing of the converter switching. The VPC strategy is implemented in a parallel resonant DC Link converter, and simulations with the VPC strategy turned on and turned off are compared. Experimental verification of the VPC strategy is done in a three-phase parallel resonant DC Link converter and measurements of switching losses are present. It is concluded that the switching losses are low and the Link Voltage peak can be controlled without any additional clamp circuits using VPC.

Liuchen Chang - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Adaptive Observer-Based DC-Link Voltage Control for Grid-Connected Power Converters
    2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao
    Abstract:

    In the past decades, renewable energy has been experiencing significant growth due to the increasing energy demand and critical environmental issues. In order to perform power conversion and grid integration for these distributed energy resources, grid-connected power converters are therefore widely used. In a typical three-phase grid-connected power converter, DC-Link capacitors are normally used as an energy buffer to maintain a proper DC Voltage for the power conversion. However, the DC-Link Voltage varies significantly when the input power from the distributed energy resources changes rapidly. Hence, a proper DC-Link Voltage controller is essential to perform fast DC-Link Voltage regulation. In this paper, a novel adaptive observer-based DC-Link Voltage control is proposed for three-phase grid-connected power converters to minimize the DC-Link Voltage fluctuation and to improve the stability of the state observer.

  • Novel Nonlinear DC-Link Voltage Control for Small-Scale Grid-Connected Wind Power Converters
    2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao
    Abstract:

    A novel nonlinear observer-based DC-Link Voltage control algorithm is proposed in this paper for small-scale grid-connected variable-speed wind power converters to minimize the Voltage fluctuation across DC-Link capacitors caused by wind power variations. The DC-Link capacitors, in wind power converters, are normally used to buffer the difference between the input and output power. However, the DC-Link Voltage varies significantly under rapidly changing working conditions. Hence, a proper DC-Link Voltage controller is essential to regulate the DC-Link Voltage in order to minimize these fluctuations. The proposed algorithm estimates the power fed into the converter system using a nonlinear observer integrated with a PI controller, combining the advantages of fast dynamic response capability offered by the proposed observer and control robustness from the PI controller without any additional measurement components. The effectiveness of the proposed control algorithm is verified by both simulation and experimental results.

  • A Novel DC-Link Voltage Control for Small-Scale Grid-Connected Wind Energy Conversion System
    2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao, Shuang Xu
    Abstract:

    This paper proposed a novel DC-Link Voltage control method for small-scale grid-connected three-phase power converters in variable-speed wind energy conversion systems to minimize the fluctuation in the DC-Link Voltage caused by wind power variations. In a typical three-phase PWM converter, DC-Link capacitors are normally used as an energy buffer to balance the power difference between the input and output, but the Voltage across the capacitors varies significantly under rapidly changing working conditions. Hence, a proper DC-Link Voltage control is essential to perform fast DC-Link Voltage regulation to minimize these fluctuations. The proposed DC-Link Voltage control method estimates the input power of the converter using a state observer and integrates with a conventional PI controller, combining the advantages of the robustness of a PI controller and the fast-transient response and disturbance rejection capability offered by the observer-based feed-forward compensation but without additional measurement components. The comparison between the proposed control algorithm and a conventional PI controller is presented in both simulations and experiments in this paper to verify the effectiveness and the advantages of the proposed observer-based DC-Link control algorithm.

  • A new DC Link Voltage boost scheme of IGBT inverters for wind energy extraction
    2000 Canadian Conference on Electrical and Computer Engineering. Conference Proceedings. Navigating to a New Era (Cat. No.00TH8492), 2000
    Co-Authors: Hong Huang, Liuchen Chang
    Abstract:

    This paper presents a new DC-Link Voltage boost method for adequate Voltage coordination in grid-connected wind energy conversion inverter systems using insulated-gate bipolar transistors (IGBTs). The method provides a simple structure to solve DC-Link Voltage shortage problem at low winds by adding one switch between one of rectifier input legs and the middle point of the DC Link reservoir capacitor. The switch, turned on at low winds, can boost the DC Link Voltage up to a double value compared to the situation without the switch. Consequently, a double Voltage rectifier is used for this method. While the switch is turned off at high winds, the system brings the DC Link Voltage back to the normal to eliminate frequent overVoltage protection. The double Voltage rectifier method can make more wind energy extraction at low winds than that without it. However, it brings an unsymmetrical operation to the turbine generator, thus resulting in a mechanical vibration of the wind turbine. To solve the unsymmetrical operation problem, a symmetrical double Voltage rectifier is proposed. In this paper, both methods are described. The computer simulation results on both methods are presented.

J.k. Pedersen - One of the best experts on this subject based on the ideXlab platform.

  • Link Voltage peak control of parallel resonant converter by control of the converter switching instant
    IEEE Transactions on Power Electronics, 1997
    Co-Authors: Stig Munk-nielsen, Frede Blaabjerg, J.k. Pedersen
    Abstract:

    This paper describes a new control strategy of the parallel resonant DC Link converter called Voltage peak control (VPC). VPC limits the Link Voltage to twice the DC Link Voltage. The strategy eliminates the need of additional power electronic components that clamp the Link Voltage. The operation of the resonant Link is described highlighting the factors that influence on the Link Voltage peak. The paper describes how control of the Link Voltage peak is possible by appropriate timing of the converter switching. The VPC strategy is implemented in a parallel resonant DC Link converter, and simulations with the VPC strategy turned on and turned off are compared. Experimental verification of the VPC strategy is done in a three-phase parallel resonant DC Link converter and measurements of switching losses are present. It is concluded that the switching losses are low and the Link Voltage peak can be controlled without any additional clamp circuits using VPC.

  • A new parallel resonant converter Link Voltage control
    Proceedings of International Conference on Power Electronics Drives and Energy Systems for Industrial Growth, 1996
    Co-Authors: Stig Munk-nielsen, F.f. Protiwa, J.k. Pedersen, Frede Blaabjerg, Oscar Apeldoorn
    Abstract:

    This paper describes a new control strategy of the parallel resonant DC Link converter called Voltage peak control (VPC). VPC limits the Link Voltage to twice the DC Link Voltage. The strategy eliminates the need of additional power electronic components that clamp the Link Voltage. A presentation of the VPC strategy is done and then follows an experimental verification which shows a good agreement between theoretical and measured values. The VPC strategy introduces hard switching at low Voltage at a limited number of switching instants. The switching losses are experimentally measured and evaluated. A substantial reduction of the switching losses using a lower turn-off Voltage is measured compared to switching losses in PWM-VSI. Finally, the VPC strategy is demonstrated experimentally and it works according to theory.

  • Link Voltage peak control of parallel resonant converter by control of the converter switching instant
    Proceedings of PESC '95 - Power Electronics Specialist Conference, 1995
    Co-Authors: Stig Munk-nielsen, Frede Blaabjerg, J.k. Pedersen
    Abstract:

    This paper describes a new control strategy of the parallel resonant DC Link power converter called Voltage peak control (VPC). VPC limits the Link Voltage to twice the DC Link Voltage. The strategy eliminates the need for additional power electronic components to clamp the Link Voltage. The operation of the resonant Link is described highlighting the factors that influence the Link Voltage peak. The paper describes how control of the Link Voltage peak is possible by appropriate timing of power converter switching. The VPC strategy is implemented in a parallel resonant DC Link power converter and simulations with the VPC strategy turned on and turned off are compared. Finally, experimental verification of the VPC strategy and measurements of switching losses are presented. It is concluded that the switching losses are low and the Link Voltage peak can be controlled without additional clamp circuits using VPC.

Shuang Xu - One of the best experts on this subject based on the ideXlab platform.

  • A Novel DC-Link Voltage Control for Small-Scale Grid-Connected Wind Energy Conversion System
    2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao, Shuang Xu
    Abstract:

    This paper proposed a novel DC-Link Voltage control method for small-scale grid-connected three-phase power converters in variable-speed wind energy conversion systems to minimize the fluctuation in the DC-Link Voltage caused by wind power variations. In a typical three-phase PWM converter, DC-Link capacitors are normally used as an energy buffer to balance the power difference between the input and output, but the Voltage across the capacitors varies significantly under rapidly changing working conditions. Hence, a proper DC-Link Voltage control is essential to perform fast DC-Link Voltage regulation to minimize these fluctuations. The proposed DC-Link Voltage control method estimates the input power of the converter using a state observer and integrates with a conventional PI controller, combining the advantages of the robustness of a PI controller and the fast-transient response and disturbance rejection capability offered by the observer-based feed-forward compensation but without additional measurement components. The comparison between the proposed control algorithm and a conventional PI controller is presented in both simulations and experiments in this paper to verify the effectiveness and the advantages of the proposed observer-based DC-Link control algorithm.

Guanhong Song - One of the best experts on this subject based on the ideXlab platform.

  • A Novel Adaptive Observer-Based DC-Link Voltage Control for Grid-Connected Power Converters
    2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao
    Abstract:

    In the past decades, renewable energy has been experiencing significant growth due to the increasing energy demand and critical environmental issues. In order to perform power conversion and grid integration for these distributed energy resources, grid-connected power converters are therefore widely used. In a typical three-phase grid-connected power converter, DC-Link capacitors are normally used as an energy buffer to maintain a proper DC Voltage for the power conversion. However, the DC-Link Voltage varies significantly when the input power from the distributed energy resources changes rapidly. Hence, a proper DC-Link Voltage controller is essential to perform fast DC-Link Voltage regulation. In this paper, a novel adaptive observer-based DC-Link Voltage control is proposed for three-phase grid-connected power converters to minimize the DC-Link Voltage fluctuation and to improve the stability of the state observer.

  • Novel Nonlinear DC-Link Voltage Control for Small-Scale Grid-Connected Wind Power Converters
    2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao
    Abstract:

    A novel nonlinear observer-based DC-Link Voltage control algorithm is proposed in this paper for small-scale grid-connected variable-speed wind power converters to minimize the Voltage fluctuation across DC-Link capacitors caused by wind power variations. The DC-Link capacitors, in wind power converters, are normally used to buffer the difference between the input and output power. However, the DC-Link Voltage varies significantly under rapidly changing working conditions. Hence, a proper DC-Link Voltage controller is essential to regulate the DC-Link Voltage in order to minimize these fluctuations. The proposed algorithm estimates the power fed into the converter system using a nonlinear observer integrated with a PI controller, combining the advantages of fast dynamic response capability offered by the proposed observer and control robustness from the PI controller without any additional measurement components. The effectiveness of the proposed control algorithm is verified by both simulation and experimental results.

  • A Novel DC-Link Voltage Control for Small-Scale Grid-Connected Wind Energy Conversion System
    2019 IEEE Applied Power Electronics Conference and Exposition (APEC), 2019
    Co-Authors: Guanhong Song, Liuchen Chang, Riming Shao, Shuang Xu
    Abstract:

    This paper proposed a novel DC-Link Voltage control method for small-scale grid-connected three-phase power converters in variable-speed wind energy conversion systems to minimize the fluctuation in the DC-Link Voltage caused by wind power variations. In a typical three-phase PWM converter, DC-Link capacitors are normally used as an energy buffer to balance the power difference between the input and output, but the Voltage across the capacitors varies significantly under rapidly changing working conditions. Hence, a proper DC-Link Voltage control is essential to perform fast DC-Link Voltage regulation to minimize these fluctuations. The proposed DC-Link Voltage control method estimates the input power of the converter using a state observer and integrates with a conventional PI controller, combining the advantages of the robustness of a PI controller and the fast-transient response and disturbance rejection capability offered by the observer-based feed-forward compensation but without additional measurement components. The comparison between the proposed control algorithm and a conventional PI controller is presented in both simulations and experiments in this paper to verify the effectiveness and the advantages of the proposed observer-based DC-Link control algorithm.