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Man-chung Wong - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Dc-Link Voltage Controls in Three-Phase Four-Wire Hybrid Active Power Filters
    IEEE Transactions on Power Electronics, 2013
    Co-Authors: Wai-hei Choi, Man-chung Wong
    Abstract:

    This paper investigates different Dc-Link Voltage control strategies in a three-phase four-wire LC coupling hybrid active power filter (LC -HAPF) for reactive power compensation. By using direct current (current reference) pulsewidth modulation (PWM) control method, to achieve Dc-Link Voltage self-charging function during LC -HAPF start-up process, the Dc-Link Voltage control signal feedback as reactive current component is more effective than the traditional method as an active current component. However, when the LC-HAPF is performing dynamic reactive power compensation, this Dc-Link Voltage control scheme will influence the reactive power compensation, and thus, makes the LC-HAPF lack of success to carry out dynamic reactive power compensation. In this paper, a novel Dc-Link Voltage control scheme for LC-HAPF is proposed so that the Dc-Link Voltage control with start-up self-charging process can be obtained as well as providing dynamic reactive power compensation. Representative simulation and experimental results of the three-phase four-wire center-spilt LC-HAPF are presented to verify all deductions, and also show the effectiveness of the proposed Dc-Link Voltage control scheme in dynamic reactive power compensation.

  • Adaptive Dc-Link Voltage-Controlled Hybrid Active Power Filters for Reactive Power Compensation
    IEEE Transactions on Power Electronics, 2012
    Co-Authors: Wai-hei Choi, Man-chung Wong
    Abstract:

    This paper presents a novel adaptive Dc-Link Voltage-controlled LC coupling hybrid active power filter (LC-HAPF) for reducing switching loss and switching noise under reactive power compensation. First, the mathematical relationship between LC-HAPF Dc-Link Voltage and reactive power compensation range is deduced and presented. Based on the compensation range analysis, the required minimum Dc-Link Voltage with respect to different loading reactive power is deduced. Then, an adaptive Dc-Link Voltage controller for the three-phase four-wire LC-HAPF is proposed, in which the Dc-Link Voltage as well as the reactive power compensation range can be adaptively changed according to different inductive loading situations. Therefore, the compensation range, switching loss, and switching noise of the LC-HAPF can be determined and reduced correspondingly. In this paper, the reference Dc-Link Voltage is classified into certain levels for selection in order to alleviate the problem of Dc Voltage fluctuation caused by its reference frequent variation, and hence reducing the fluctuation impact on the compensation performances. Finally, representative simulation and experimental results of a three-phase four-wire center-split LC -HAPF are presented to verify the validity and effectiveness of the proposed adaptive Dc-Link Voltage-controlled LC-HAPF in dynamic reactive power compensation.

Wai-hei Choi - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Dc-Link Voltage Controls in Three-Phase Four-Wire Hybrid Active Power Filters
    IEEE Transactions on Power Electronics, 2013
    Co-Authors: Wai-hei Choi, Man-chung Wong
    Abstract:

    This paper investigates different Dc-Link Voltage control strategies in a three-phase four-wire LC coupling hybrid active power filter (LC -HAPF) for reactive power compensation. By using direct current (current reference) pulsewidth modulation (PWM) control method, to achieve Dc-Link Voltage self-charging function during LC -HAPF start-up process, the Dc-Link Voltage control signal feedback as reactive current component is more effective than the traditional method as an active current component. However, when the LC-HAPF is performing dynamic reactive power compensation, this Dc-Link Voltage control scheme will influence the reactive power compensation, and thus, makes the LC-HAPF lack of success to carry out dynamic reactive power compensation. In this paper, a novel Dc-Link Voltage control scheme for LC-HAPF is proposed so that the Dc-Link Voltage control with start-up self-charging process can be obtained as well as providing dynamic reactive power compensation. Representative simulation and experimental results of the three-phase four-wire center-spilt LC-HAPF are presented to verify all deductions, and also show the effectiveness of the proposed Dc-Link Voltage control scheme in dynamic reactive power compensation.

  • Adaptive Dc-Link Voltage-Controlled Hybrid Active Power Filters for Reactive Power Compensation
    IEEE Transactions on Power Electronics, 2012
    Co-Authors: Wai-hei Choi, Man-chung Wong
    Abstract:

    This paper presents a novel adaptive Dc-Link Voltage-controlled LC coupling hybrid active power filter (LC-HAPF) for reducing switching loss and switching noise under reactive power compensation. First, the mathematical relationship between LC-HAPF Dc-Link Voltage and reactive power compensation range is deduced and presented. Based on the compensation range analysis, the required minimum Dc-Link Voltage with respect to different loading reactive power is deduced. Then, an adaptive Dc-Link Voltage controller for the three-phase four-wire LC-HAPF is proposed, in which the Dc-Link Voltage as well as the reactive power compensation range can be adaptively changed according to different inductive loading situations. Therefore, the compensation range, switching loss, and switching noise of the LC-HAPF can be determined and reduced correspondingly. In this paper, the reference Dc-Link Voltage is classified into certain levels for selection in order to alleviate the problem of Dc Voltage fluctuation caused by its reference frequent variation, and hence reducing the fluctuation impact on the compensation performances. Finally, representative simulation and experimental results of a three-phase four-wire center-split LC -HAPF are presented to verify the validity and effectiveness of the proposed adaptive Dc-Link Voltage-controlled LC-HAPF in dynamic reactive power compensation.

Seung-ki Sul - One of the best experts on this subject based on the ideXlab platform.

  • Dc-Link Voltage Stabilization for Reduced Dc-Link Capacitor Inverter
    IEEE Transactions on Industry Applications, 2014
    Co-Authors: Wook-ji Lee, Seung-ki Sul
    Abstract:

    In conventional motor drive systems using pulsewidth modulation (PWM) inverters, large electrolytic capacitors are used for stabilization of the Dc-Link Voltage. Since the electrolytic capacitors are bulky and reduce reliability of the system due to short lifetime, there have been many efforts to eliminate or reduce the electrolytic capacitors in the motor drive system. However, the PWM inverter with reduced Dc-Link capacitor has a problem that the Dc-Link Voltage is less stable compared to the conventional inverter because the capability of storing energy is also reduced. In this paper, a Dc-Link Voltage stabilization algorithm using an active damping is proposed so that the Dc-Link Voltage can be stabilized with reduced Dc-Link capacitor. To achieve load-/source-independent stabilization, a source state estimator which estimates both source Voltage and current is also proposed. The fluctuation of the Dc-Link Voltage due to a step load change can be also suppressed under the tolerance range using the estimated source current. The effectiveness of the proposed methods is evaluated by experimental results.

  • Dc Link Voltage stabilization for reduced Dc Link capacitor inverter
    Energy Conversion Congress and Exposition, 2009
    Co-Authors: Wookjin Lee, Seung-ki Sul
    Abstract:

    A PMW inverter with reduced Dc-Link capacitor has a problem that the Dc-Link Voltage is less stable compared to the conventional inverter because of the lack of energy storage capability. The proposed Dc-Link Voltage stabilization algorithm using active damping gives a solution to this problem. To achieve load/source independent stabilization, the source state estimator which estimates both source Voltage and current is also proposed. The proposed methods are evaluated by experimental results. While the inverter with a small Dc Link capacitor tripped due to Dc-Link overVoltage fault at step load change, the fluctuation of Dc-Link Voltage of the inverter is suppressed under the tolerance range with the proposed method at the same step load change.

Bhim Singh - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive Dc-Link Voltage Based Bi-Directional Charger for Electric Vehicles
    2019 IEEE International Conference on Environment and Electrical Engineering and 2019 IEEE Industrial and Commercial Power Systems Europe (EEEIC I&CPS, 2019
    Co-Authors: Bhim Singh, Anjeet Verma
    Abstract:

    This paper proposes an adaptive Dc Link Voltage based bi-directional electric vehicle (EV) charger, which operates in all the four quadrants of P-Q (active-reactive powers) plane. The four quadrants operation of charger enables the, only active (charging/discharging), only reactive (inductive/capacitive) and simultaneous active (charging/discharging) and reactive power (inductive /capacitive) exchange with the grid. This paper also proposes an adaptive Dc Link Voltage strategy for estimating the reference Dc Link Voltage, so that the charger can operate uninterruptedly under all Voltage conditions (over Voltage and under Voltage). The adaptive Dc Link Voltage also helps in minimizing the high-frequency ripple in the grid current. Due to which the total harmonic distortion (THD) of the grid current improves significantly. Because of this, the charger is able to maintain, the supply current THD below 5% in all operating mode. The designed charger operate with 230V, 50Hz single phase supply. The experimental test results captured in both steady state and dynamic conditions, validates the design and control of proposed charger.

  • an adjustable Dc Link Voltage based control of multifunctional grid interfaced solar pv system
    IEEE Journal of Emerging and Selected Topics in Power Electronics, 2017
    Co-Authors: Chinmay Jain, Bhim Singh
    Abstract:

    This paper presents a grid supported solar energy conversion system with an adjustable Dc Link Voltage for common point of interconnection (CP) Voltage variations. A two-stage circuit topology is proposed, wherein the first stage is a boost converter, which serves for maximum power point tracking, and the second stage is a grid tied Voltage source converter (VSC), which not only feeds extracted solar photovoltaic (PV) energy into the three-phase distribution system but also serves for harmonics mitigation, reactive power compensation, and grid current balancing. An interweaved double-frequency second-order generalized integrator-based control algorithm is proposed for control of this multifunctional VSC, which possesses the feature of good steady-state performance along with fast dynamic response even under sudden load changes at CPI. Moreover, a feed-forward term for the solar PV contribution is used to enhance the dynamic response for climatic changes and CPI Voltage variation. An adjustable Dc Link Voltage structure is used to accommodate CPI Voltage variation, which helps in reduction of losses in the power circuit. To implement adjustable Dc Link Voltage structure, the reference Dc Link Voltage is adjusted with variation in CPI Voltage in real time. A proportional–integral controller is used to regulate Dc Link Voltage to set reference value. A wide range of experimental results are shown to demonstrate the features of the proposed system. The total harmonic distortion of grid current has been found well under IEEE-519 standard even under nonlinear loads at CPI.

  • a three phase grid tied spv system with adaptive Dc Link Voltage for cpi Voltage variations
    IEEE Transactions on Sustainable Energy, 2016
    Co-Authors: Chinmay Jain, Bhim Singh
    Abstract:

    This paper deals with a three-phase two-stage grid tied SPV (solar photo-voltaic) system. The first stage is a boost converter, which serves the purpose of MPPT (maximum power point tracking) and feeding the extracted solar energy to the Dc Link of the PV inverter, whereas the second stage is a two-level VSC (Voltage source converter) serving as PV inverter which feeds power from a boost converter into the grid. The proposed system uses an adaptive Dc Link Voltage which is made adaptive by adjusting reference Dc Link Voltage according to CPI (common point of interconnection) Voltage. The adaptive Dc Link Voltage control helps in the reduction of switching power losses. A feed forward term for solar contribution is used to improve the dynamic response. The system is tested considering realistic grid Voltage variations for under Voltage and over Voltage. The performance improvement is verified experimentally. The proposed system is advantageous not only in cases of frequent and sustained under Voltage (as in the cases of far radial ends of Indian grid) but also in case of normal Voltages at CPI. The THD (total harmonics distortion) of grid current has been found well under the limit of an IEEE-519 standard.

  • a single phase two stage grid interfaced spv system with adjustable Dc Link Voltage for vsc under non ideal grid conditions
    IEEE International Conference on Power Electronics Drives and Energy Systems, 2014
    Co-Authors: Chinmay Jain, Bhim Singh
    Abstract:

    This paper deals with single phase grid interfaced SPV (Solar Photo Voltaic) system. A two stage power circuit topology is used in the presented work, in which the first stage is a boost converter, which serves the purpose of MPPT (Maximum Power Point Tracking) and the second stage is a PV inverter which serves the purpose of feeding extracted energy into the grid. A feed-forward term for solar contribution is used to improve the dynamic response. The PV inverter Dc Link Voltage is continuously adjusted according to PCC (Point of Common Coupling) Voltage, which in turn helps in reduction of power losses. A PI (Proportional Integral) controller is used to regulate the Dc Link Voltage to desired reference Voltage. The system is modeled and simulated on MATLAB based platform. A wide range of simulation results are shown to demonstrate all features of proposed system. The system is tested considering realistic non ideal grid conditions. The proposed system is advantageous in cases of frequent and sustained grid Voltage variations (such is the case of far radial ends of Indian grid). The performance of proposed system is found satisfactory for wide variation of grid Voltage. The THD (Total Harmonics Distortion) of grid current has been found well under IEEE-519 standard.

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

  • a novel seven level active neutral point clamped converter with reduced active switching devices and Dc Link Voltage
    IEEE Transactions on Power Electronics, 2019
    Co-Authors: Yam P Siwakoti, Akshay Mahajan, Daniel J Rogers, Frede Blaabjerg
    Abstract:

    This paper presents a novel seven-level inverter topology for medium-Voltage high-power applications. It consists of eight active switches and two inner flying capacitor (FC) units forming a similar structure as in a conventional active neutral-point-clamped (ANPC) inverter. This unique arrangement reduces the number of active and passive components. A simple modulation technique reduces cost and complexity in the control system design without compromising reactive power capability. In addition, compared to major conventional seven-level inverter topologies, such as the neutral point clamped, FC, cascaded H-bridge, and ANPC topologies, the new topology reduces the Dc-Link Voltage requirement by 50%. This recued Dc-Link Voltage makes the new topology appealing for various industrial applications. Experimental results from a 2.2-kVA prototype are presented to support the theoretical analysis presented in this paper. The prototype demonstrates a conversion efficiency of around 97.2% ± 1% for a wide load range.

  • harmonic elimination technique for a single phase multilevel converter with unequal Dc Link Voltage levels
    Iet Power Electronics, 2012
    Co-Authors: Negareh Ghasemi, Firuz Zare, Arash A Boora, Arindam Ghosh, Christian M Langton, Frede Blaabjerg
    Abstract:

    Multilevel converters, because of the benefits they attract in generating high quality output Voltage, are used in several applications. Various modulation and control techniques are introduced by several researchers to control the output Voltage of the multilevel converters like space vector modulation and harmonic elimination (HE) methods. Multilevel converters may have a Dc Link with equal or unequal Dc Voltages. In this study a new HE technique based on the HE method is proposed for multilevel converters with unequal Dc Link Voltage. The Dc Link Voltage levels are considered as additional variables for the HE method and the Voltage levels are defined based on the HE results. Increasing the number of Voltage levels can reduce lower order harmonic content because of the fact that more variables are created. In comparison to previous methods, this new technique has a positive effect on the output Voltage quality by reducing its total harmonic distortion, which must take into consideration for some applications such as uninterruptable power supply, motor drive systems and piezoelectric transducer excitation. In order to verify the proposed modulation technique, MATLAB simulations and experimental tests are carried out for a single-phase four-level diode-clamped converter.

  • adaptive svm to compensate Dc Link Voltage ripple for four switch three phase Voltage source inverters
    IEEE Transactions on Power Electronics, 1999
    Co-Authors: Frede Blaabjerg, Dorin O Neacsu, John Kim Pedersen
    Abstract:

    An adaptive space vector modulation (SVM) approach to compensate the Dc-Link Voltage ripple in a B4 inverter is proposed and examined in detail. The theory, design, and performance of this pulsewidth modulation (PWM) method are presented, and the method effectiveness is demonstrated by extensive simulations and experiments. High-quality output currents are guaranteed by this approach even with substantial Dc-Voltage variations that might be caused by an unbalanced AC supply system, the diode rectification of the line Voltages, and circulation of one output phase current through the split capacitor bank. The application of this approach to induction machine drives is also discussed. It is concluded that the Dc-Voltage ripple effect on the B4 inverter output can be minimized by an adaptive SVM algorithm with the advantage of improving the response of the Dc-Link filter and the output quality of the inverter becoming high.

  • adaptive svm to compensate Dc Link Voltage ripple for component minimized Voltage source inverters
    Power Electronics Specialists Conference, 1997
    Co-Authors: Frede Blaabjerg, Dorin O Neacsu, John Kim Pedersen
    Abstract:

    An adaptive space vector modulation approach to compensate the Dc-Link Voltage ripple in a B4 inverter is examined in detail. The theory, design and performance of this PWM method are presented and the method effectiveness is demonstrated by extensive simulations and experiments. High-quality output currents are guaranteed by this approach even with substantial Dc Voltage variations that might be caused by unbalanced AC supply system, diode rectification of the line Voltages and circulation of one phase current through the split capacitor bank. The application of this approach to induction machine drives is also discussed. It is concluded that the Dc ripple effect on the B4 inverter output can be minimized by an adaptive SVM algorithm with the advantage of improving the response of the Dc-Link filter and the output quality is high.