The Experts below are selected from a list of 102435 Experts worldwide ranked by ideXlab platform

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

  • stability analysis and Controller synthesis for single loop voltage Controlled vsis
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Xiongfei Wang, Poh Chiang Loh, Frede Blaabjerg
    Abstract:

    This paper analyzes the stability of Digitally voltage-Controlled voltage-source inverters (VSIs) with the linear voltage regulators. It is revealed that the phase lags, caused by using the resonant Controller and the time delay of a Digital Control System, can stabilize the single-loop voltage Control without damping of the LC -filter resonance. The stability region for the Digital single-loop resonant voltage Control is then identified, considering the effects of different discretization methods for the resonant Controller. An enhanced voltage Control approach with a widened stability region is subsequently proposed, and a step-by-step design method of the proposed Controller is developed based on the root contours in the discrete z -domain. Simulations and experimental tests of a 400-Hz VSI System validate the stability analysis and the performance of the proposed Control approach.

  • harmonic instability assessment using state space modeling and participation analysis in inverter fed power Systems
    IEEE Transactions on Industrial Electronics, 2017
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents a harmonic instability analysis method using state-space modeling and participation analysis in the inverter-fed ac power Systems. A full-order state-space model for the droop-Controlled distributed generation (DG) inverter is built first, including the time delay of the Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the DG inverter model, an overall state-space model of a two-inverter-fed System is established. The eigenvalue-based stability analysis is then presented to assess the influence of Controller parameters on the harmonic instability of the power System. Moreover, the harmonic-frequency oscillation modes are identified, where participation analysis is presented to evaluate the contributions of different states to these modes and to further reveal how the System gives rise to harmonic instability. Based on the participation analysis, a reduced-order model for harmonic instability analysis is also proposed. The experimental results are presented for validating the theoretical analyses.

  • stability analysis and Controller synthesis for Digital single loop voltage Controlled inverters
    Applied Power Electronics Conference, 2016
    Co-Authors: Xiongfei Wang, Poh Chiang Loh, Frede Blaabjerg
    Abstract:

    This paper analyzes first the stability of single-loop Digital voltage Control scheme for the LC-filtered voltage source inverters. It turns out that the phase lag, caused by the time delay of Digital Control System and by the use of integral Controller, can stabilize the voltage loop without damping of LC-filter resonance. The stability regions are then identified with alternative voltage Controller synthesized. For further widening the stability region, an active damping approach is proposed and co-designed with the voltage Controller in the discrete z-domain. Simulations and experimental results of both 50-Hz and 400-Hz Systems validate the theoretical analyses and the performance of the approach.

  • eigenvalue based harmonic stability analysis method in inverter fed power Systems
    Conference of the Industrial Electronics Society, 2015
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents an eigenvalue-based harmonic stability analysis method for inverter-fed power Systems. A full-order small-signal model for a droop-Controlled Distributed Generation (DG) inverter is built first, including the time delay of Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the inverter model, an overall small-signal model of a two-inverter-fed System is then established, and the eigenvalue-based stability analysis is subsequently performed to assess the influence of Controller parameters on the harmonic resonance and instability in the power System. Eigenvalues associated with time delay of inverter and inner Controller parameters is obtained, which shows the time delay has an important effect on harmonic instability of inverter-fed power Systems. Simulation results are given for validating the proposed harmonic stability analysis method.

  • analysis and design of grid current feedback active damping for lcl resonance in grid connected voltage source converters
    European Conference on Cognitive Ergonomics, 2014
    Co-Authors: Xiongfei Wang, Frede Blaabjerg, Poh Chiang Loh
    Abstract:

    This paper investigates the active damping of LCL- filter resonance within single-loop grid current Control of grid- connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across the grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay in a Digital Control System. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A Systematic design method of the high- pass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly, experimental tests are presented to validate the theoretical analysis.

Xiongfei Wang - One of the best experts on this subject based on the ideXlab platform.

  • stability analysis and Controller synthesis for single loop voltage Controlled vsis
    IEEE Transactions on Power Electronics, 2017
    Co-Authors: Xiongfei Wang, Poh Chiang Loh, Frede Blaabjerg
    Abstract:

    This paper analyzes the stability of Digitally voltage-Controlled voltage-source inverters (VSIs) with the linear voltage regulators. It is revealed that the phase lags, caused by using the resonant Controller and the time delay of a Digital Control System, can stabilize the single-loop voltage Control without damping of the LC -filter resonance. The stability region for the Digital single-loop resonant voltage Control is then identified, considering the effects of different discretization methods for the resonant Controller. An enhanced voltage Control approach with a widened stability region is subsequently proposed, and a step-by-step design method of the proposed Controller is developed based on the root contours in the discrete z -domain. Simulations and experimental tests of a 400-Hz VSI System validate the stability analysis and the performance of the proposed Control approach.

  • harmonic instability assessment using state space modeling and participation analysis in inverter fed power Systems
    IEEE Transactions on Industrial Electronics, 2017
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents a harmonic instability analysis method using state-space modeling and participation analysis in the inverter-fed ac power Systems. A full-order state-space model for the droop-Controlled distributed generation (DG) inverter is built first, including the time delay of the Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the DG inverter model, an overall state-space model of a two-inverter-fed System is established. The eigenvalue-based stability analysis is then presented to assess the influence of Controller parameters on the harmonic instability of the power System. Moreover, the harmonic-frequency oscillation modes are identified, where participation analysis is presented to evaluate the contributions of different states to these modes and to further reveal how the System gives rise to harmonic instability. Based on the participation analysis, a reduced-order model for harmonic instability analysis is also proposed. The experimental results are presented for validating the theoretical analyses.

  • stability analysis and Controller synthesis for Digital single loop voltage Controlled inverters
    Applied Power Electronics Conference, 2016
    Co-Authors: Xiongfei Wang, Poh Chiang Loh, Frede Blaabjerg
    Abstract:

    This paper analyzes first the stability of single-loop Digital voltage Control scheme for the LC-filtered voltage source inverters. It turns out that the phase lag, caused by the time delay of Digital Control System and by the use of integral Controller, can stabilize the voltage loop without damping of LC-filter resonance. The stability regions are then identified with alternative voltage Controller synthesized. For further widening the stability region, an active damping approach is proposed and co-designed with the voltage Controller in the discrete z-domain. Simulations and experimental results of both 50-Hz and 400-Hz Systems validate the theoretical analyses and the performance of the approach.

  • eigenvalue based harmonic stability analysis method in inverter fed power Systems
    Conference of the Industrial Electronics Society, 2015
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents an eigenvalue-based harmonic stability analysis method for inverter-fed power Systems. A full-order small-signal model for a droop-Controlled Distributed Generation (DG) inverter is built first, including the time delay of Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the inverter model, an overall small-signal model of a two-inverter-fed System is then established, and the eigenvalue-based stability analysis is subsequently performed to assess the influence of Controller parameters on the harmonic resonance and instability in the power System. Eigenvalues associated with time delay of inverter and inner Controller parameters is obtained, which shows the time delay has an important effect on harmonic instability of inverter-fed power Systems. Simulation results are given for validating the proposed harmonic stability analysis method.

  • analysis and design of grid current feedback active damping for lcl resonance in grid connected voltage source converters
    European Conference on Cognitive Ergonomics, 2014
    Co-Authors: Xiongfei Wang, Frede Blaabjerg, Poh Chiang Loh
    Abstract:

    This paper investigates the active damping of LCL- filter resonance within single-loop grid current Control of grid- connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across the grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay in a Digital Control System. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A Systematic design method of the high- pass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly, experimental tests are presented to validate the theoretical analysis.

Seunghi Lee - One of the best experts on this subject based on the ideXlab platform.

  • multirate Digital Control System design and its application to computer disk drives
    IEEE Transactions on Control Systems and Technology, 2006
    Co-Authors: Seunghi Lee
    Abstract:

    A computationally efficient fixed order multirate Digital Control System is presented. Introducing a periodically time-varying gain, a multirate Digital Controller is designed, that works without using intersample states and delivers a stable ripple-free closed-loop with discrete-time state matching at each Control update instant. Increasing the Control update rate thereby tends to improve intersample behavior of the closed-loop System. The multirate Controller outputs Control at each Control update instant, while the multirate Control scheme is computed in the background during output measurement sampling period thereby reducing the computational burden for implementation. The proposed multirate scheme is applied to disk drive actuator Control. Application results demonstrate the utility of the proposed multirate Digital Control scheme for improved disk drive actuator Control.

  • multirate Digital Control System design
    American Control Conference, 2002
    Co-Authors: Seunghi Lee, Younghoon Kim, Chung Choo Chung
    Abstract:

    A computation effective fixed order multirate Digital Control System is presented. Introducing a periodically time varying gain, a multirate Digital Controller is designed, that works without using inter-sample states and delivers a stable closed loop with predictable behavior at every Control update instant. The multirate Controller outputs Control at each Control update instant, while the multirate Control scheme is evenly computed every measurement sampling period thereby eliminating the need for very powerful processors for implementation. An illustrative example is provided to demonstrate the usefulness of the proposed multirate Digital Control scheme.

Zhe Chen - One of the best experts on this subject based on the ideXlab platform.

  • harmonic instability assessment using state space modeling and participation analysis in inverter fed power Systems
    IEEE Transactions on Industrial Electronics, 2017
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents a harmonic instability analysis method using state-space modeling and participation analysis in the inverter-fed ac power Systems. A full-order state-space model for the droop-Controlled distributed generation (DG) inverter is built first, including the time delay of the Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the DG inverter model, an overall state-space model of a two-inverter-fed System is established. The eigenvalue-based stability analysis is then presented to assess the influence of Controller parameters on the harmonic instability of the power System. Moreover, the harmonic-frequency oscillation modes are identified, where participation analysis is presented to evaluate the contributions of different states to these modes and to further reveal how the System gives rise to harmonic instability. Based on the participation analysis, a reduced-order model for harmonic instability analysis is also proposed. The experimental results are presented for validating the theoretical analyses.

  • eigenvalue based harmonic stability analysis method in inverter fed power Systems
    Conference of the Industrial Electronics Society, 2015
    Co-Authors: Yanbo Wang, Frede Blaabjerg, Xiongfei Wang, Zhe Chen
    Abstract:

    This paper presents an eigenvalue-based harmonic stability analysis method for inverter-fed power Systems. A full-order small-signal model for a droop-Controlled Distributed Generation (DG) inverter is built first, including the time delay of Digital Control System, inner current and voltage Control loops, and outer droop-based power Control loop. Based on the inverter model, an overall small-signal model of a two-inverter-fed System is then established, and the eigenvalue-based stability analysis is subsequently performed to assess the influence of Controller parameters on the harmonic resonance and instability in the power System. Eigenvalues associated with time delay of inverter and inner Controller parameters is obtained, which shows the time delay has an important effect on harmonic instability of inverter-fed power Systems. Simulation results are given for validating the proposed harmonic stability analysis method.

Jin Bae Park - One of the best experts on this subject based on the ideXlab platform.

  • sampled data Control of fuzzy Systems based on the intelligent Digital redesign method via an improved fuzzy lyapunov functional approach
    Iet Control Theory and Applications, 2018
    Co-Authors: Han Sol Kim, Jin Bae Park, Young Hoon Joo
    Abstract:

    This study presents a linear matrix inequality (LMI) approach to the sampled-data Control of Takagi-Sugeno fuzzy Systems, based on the intelligent Digital redesign (IDR) technique. The objective of the IDR is to design a Digital Control System whose trajectory closely matches that of a given well-constructed analogue Control System by minimising the state-matching error. In this study, state-matching performance is enhanced by using a continuous-time state-matching criterion, which guarantees that the state-matching error is minimised through the entire time interval. Unlike previous studies, mismatched information of membership functions for both analogue and Digital Control Systems is directly manipulated. Moreover, the authors introduce an improved fuzzy Lyapunov functional that consists of both membership functions for analogue and Digital Control Systems, which relaxes the conservativeness of LMI conditions. Finally, two examples demonstrating the effectiveness of the authors' method are provided.

  • a new intelligent Digital redesign for t s fuzzy Systems global approach
    IEEE Transactions on Fuzzy Systems, 2004
    Co-Authors: Ho Jae Lee, Young Hoon Joo, Hagbae Kim, Wook Chang, Jin Bae Park
    Abstract:

    This paper proposes a novel and efficient global intelligent Digital redesign technique for a Takagi-Sugeno (T-S) fuzzy System. The term of intelligent Digital redesign involves converting an existing analog fuzzy-model-based Controller into an equivalent Digital counterpart in the sense of state-matching. The proposed method should be notably discriminated from the previous works in that it allows us to globally match the states of the overall closed-loop T-S fuzzy System with the predesigned analog fuzzy-model-based Controller and those with the Digitally redesigned fuzzy-model-based Controller, and further to examine the stabilizability by the redesigned Controller in the sense of Lyapunov. The key idea is that the global intelligent Digital redesign problem is viewed as a convex minimization problem of the norm distance between nonlinearly interpolated linear operators to be matched. Sufficient conditions for the global state-matching and the stability of the Digitally Controlled System are formulated in terms of linear matrix inequalities (LMIs). A complex nonlinear System, Duffing-like chaotic oscillator is simulated and demonstrated to validate the feasibility and effectiveness of the proposed Digital redesign technique, which implies the safe applicability to the Digital Control System.