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This article proposes a single-stage inductive-power-transfer (IPT) converter operating as a wireless constant-power (CP) and maximum-efficiency battery charger. By maintaining a constant output power rather than providing a constant output current throughout the dominant stage of battery charging, the IPT converter can make the utmost of its power capability, thus having a faster charging rate. The proposed single-stage IPT converter adopts series–series compensation and includes a switch-controlled capacitor (SCC) and a semiactive rectifier (SAR) in the secondary side. Manipulating the SCC and the SAR to emulate the optimum impedance of the resonator and the load, we propose a novel operation approach combining the merits of load-independent transfer characteristic and load impedance matching, to achieve a simple solution to CP charging and maximum efficiency throughout the charging process. Since the control scheme is based on fixed operating frequency and secondary-side real-time regulation, wireless feedback communication is not required. Moreover, soft switching and low voltage stress can be easily achieved in this IPT converter. [ABSTRACT FROM AUTHOR]

In this study, a minimizing inverter capacity design is proposed, and the characteristics and performance of static VAR compensator (SVC) coupling hybrid active power filters (SVC-HAPFs) are analyzed. The cost of the SVC part is much lower than that of the active inverter part, and thus, the reduction of inverter part capacity can lead to a decrease in the total cost of SVC-HAPF. To demonstrate the advantages of the proposed minimizing inverter capacity design of SVC-HAPF, comparisons are given between the conventional and the proposed SVC-HAPF designs. Comparisons are also provided among active power filters (APFs), HAPFs, and the proposed SVC-HAPF in terms of dc-link voltage, compensation range, and performance. Finally, simulation and laboratory-scale experimental results are given to validate the minimizing inverter capacity design, and to verify the characteristics and compensation performances of APF, HAPF, and the proposed SVC-HAPF. [ABSTRACT FROM AUTHOR]

This paper proposes a new type dc/ac inverter named: hybrid-coupling grid-connected inverter (HGCI) for photovoltaic active power generation with power quality conditioning, which consists of a full-bridge three-phase dc/ac inverter coupling to the power grid in series with a thyristor-controlled LC filter. Compared with the conventional inductive-coupling grid-connected inverter (IGCI) and capacitive-coupling grid-connected inverter (CGCI), the proposed HGCI has distinct characteristics of wide operational range and low dc-link operating voltage. Based on these prominent characteristics, the system cost and operational cost can be reduced. Moreover, it can transfer the active power and compensate reactive power, unbalanced power, and harmonic power simultaneously. In this paper, the analysis of the structure, parameter design, and control method of the HGCI is proposed and presented. Finally, simulation and experimental results are provided to verify the effectiveness and performance of the proposed HGCI in comparison with the IGCI and CGCI. [ABSTRACT FROM AUTHOR]

When the load generated harmonic, unbalanced, and reactive power is beyond the limited capacity of a thyristor-controlled LC-coupling hybrid active power filter (TCLC-HAPF), the TCLC-HAPF with the conventional control methods cannot provide satisfactory compensation performance. In this paper, a selective compensation control method of harmonic distortion, unbalanced and reactive power of the TCLC-HAPF is proposed, which can function even at different voltage conditions (e.g., voltage dip, voltage fault, etc.). First, the proposed control method decomposes the load power into fundamental positive-sequence reactive power, fundamental negative-sequence power (unbalanced power), and harmonic power. Then, the decomposed reactive, unbalanced, and harmonic power can be selectively or fully compensated based on the capacity of the TCLC-HAPF. Finally, simulation and experimental results are provided to verify the effectiveness of the proposed selective compensation control method for the TCLC-HAPF. [ABSTRACT FROM PUBLISHER]

This paper proposes a control strategy for a three-phase three-wire thyristor-controlled LC -coupling hybrid active power filter (TCLC-HAPF), which can balance active power and compensate reactive power and harmonic currents under unbalanced loading. Compared with TCLC-HAPF with conventional control strategy, active power filters and hybrid active power filters which either fail to perform satisfactory compensation or require high-rating active inverter part for unbalanced compensation, a control strategy was proposed for TCLC-HAPF to operate with a small rating active inverter part for a variety of loads with satisfactory performance. The control idea is to provide different firing angles for each phase of the thyristor-controlled LC-coupling part (TCLC) to balance active power and compensate reactive power, while the active inverter part aims to compensate harmonic currents. First, the required different TCLC impedances are deduced. Then, independent firing angles referenced to the phase angle of voltage across TCLC are calculated. After angle transformations, final firing angles referenced to phase angle of load voltages are obtained. In this paper, a novel controller for TCLC-HAPF under unbalanced loading is proposed. Simulation and experimental results are provided to verify the effectiveness of the proposed controller in comparison with a state-of-the-art controller. [ABSTRACT FROM PUBLISHER]

In this article, a vector proportional–integral (VPI) current controller for the LC-coupling hybrid active power (LC-HAPF) with ideally zero steady-state error, optimal transient response, and good robustness is proposed. First, the transfer function of the proposed VPI current controller is introduced, and its parameter design for obtaining optimal transient response is discussed. Second, a detailed robustness analysis of the VPI current controller, including the system parameter variation, distorted grid voltage, and grid frequency variation conditions, is proposed. Third, the digital implementation method of the VPI controller and an overall control block diagram for the LC-HAPF with the proposed VPI current controller are presented. Moreover, a comparative study and analysis between the VPI current controller and the other representative current controllers under the minimum dc-link voltage is discussed in which the VPI current controller obtains the best performances under the minimum dc-link voltage operation. The simulation and experimental results are provided to verify the advantages and effectiveness of the proposed VPI current controller for a three-phase four-wire LC-HAPF in comparison with the other representative current controllers under different dc-link voltage conditions. Finally, the robustness under different grid conditions and unbalanced compensation capability of the proposed VPI-controlled LC-HAPF are also verified by the experimental results. [ABSTRACT FROM AUTHOR]

Magnetically coupled impedance-source networks can achieve a higher voltage gain with smaller shoot-through duty ratio in comparison with the conventional impedance-source networks without coupled inductors. However, the practical voltage gain is seriously affected by the parasitic resistances in passive components and power devices, which is necessary to be investigated. This article derives and analyzes the effects of parasitic resistances on the voltage gain of magnetically coupled impedance-source networks under three different scenarios: first, different resistance ratio between parasitic resistances and output equivalent resistance, second, different shoot-through duty ratio, and third, different winding ratio. First of all, a generalized equivalent circuit model considering parasitic resistances for the three typical magnetically coupled impedance-source networks—Trans-Z-source, Г-source, and Y-source networks are proposed. Based on it, the effects of parasitic resistances on the voltage gain is mathematically derived and discussed under the aforementioned three different scenarios. And the maximum voltage gain under the consideration of the three resistance ratios simultaneously is also derived. Finally, representative simulation and experimental results are provided to verify the proposed generalized equivalent circuit models, the corresponding mathematical derivations, and the effects of the parasitic resistances on the magnetically coupled impedance-source networks. [ABSTRACT FROM AUTHOR]

This paper proposes a FPAA-FPGA/DSP-based mixed signal controller that achieves superior performance when compared with conventional digital controllers in power quality compensation. This includes adaptive signal conditioning and programmability on-the-fly, higher flexibility, parallel computation capability, and easy implementation. In practical applications, the power quality compensator may suffer from poor compensation performance, particularly during light loading. The adaptive signal gain and programmable on-the-fly functions of the mixed signal controller are intended to improve the system compensation performance, which cannot be achieved by using conventional digital controllers alone. In this study, an approximate total harmonic distortion (ATHD) is proposed to determine the total harmonic distortion value more quickly, reducing the evaluation time of the power quality compensation system performance. With hysteresis pulse width modulations, when the hysteresis error margin is designed, the ATHD can be determined instantaneously. Finally, representative simulation and experimental results of a three-phase four-wire center-split hybrid active power filter are presented. These verify the validity and effectiveness of the proposed mixed signal controller in improving current quality compensation performance during light load conditions, compared with a conventional digital controller. [ABSTRACT FROM AUTHOR]

In high-power applications, different multilevel voltage source converter (VSC) topologies are usually applied. The hybrid parallel multiconverters, which is a combination of multiactive and hybrid VSCs connecting in parallel, can be a promising solution in a high-power grid. In this article, the fusion VSC topology concept is proposed in which fusion VSC takes the advantages of both active (inductive coupling) VSC and hybrid (capacitive coupling) VSC. It corresponds to overcoming the insufficient-capacity problems when active VSCs are employed alone and vice versa. This article proposes fusion active power filter topology by combing active and hybrid power VSC through their equivalent model for power quality compensation. With the proposed VSC's equivalent model, it can reduce the converter rating by 17%–80% compared with the conventional approaches. Additionally, the corresponding control algorithm is proposed for the FAPF for power quality compensation. Finally, the simulation and real-time digital simulator hardware-in-the-loop experimental results of the proposed FAPF topology are given to demonstrate the validity and effectiveness for reducing its capacity and power loss compared with the conventional multi-VSC in power quality compensation. [ABSTRACT FROM AUTHOR]

Previous researches on space vector modulation (SVM) in active power filters (APFs) topologies find that compared with sinusoidal pulse width modulation, the SVM offers a better harmonic spectrum and has 15.47% more voltage utilization. The article not only proposes SVM for hybrid active power filters (HAPFs) but also answers the following questions. 1) Under what conditions both filters are equivalent to one another? 2) Which filter can enhance better tracking ability and better performance? 3) How the coupling component parameters and dc voltage affect the performance of both filters? The representative simulation and experimental results are given to verify the discussions. The conclusions can be application guidelines for the design of inductive and capacitive coupling inverters (e.g., APFs and HAPFs) in smart grids and development of energy internet due to their generalities to applications. [ABSTRACT FROM AUTHOR]

Railway hybrid power quality conditioner (HPQC) is advantageous over conventional railway power quality conditioner (RPC) for its reduction in operation voltage and device ratings in co-phase traction power compensation. In order to further reduce the power loss during operation, flexible dc control has been proposed. However, the operation voltage range for railway HPQC has not yet been discussed. This is important since in contrast to traditional power quality compensation devices, active power compensation is involved in co-phase traction power. Compensation capability in co-phase traction power thus does refer not only to reactive power compensation but also to active power compensation ability. Satisfactory compensation performance can be provided only when railway HPQC can provide enough active and reactive compensation power output at the same time. In this paper, the effects of operation range in flexible dc voltage control on railway HPQC compensation capability is briefly discussed and analyzed. The analysis is verified via PSCAD simulations. A laboratory-scaled hardware prototype is also constructed to obtain experimental results for further verifications. [ABSTRACT FROM AUTHOR]

Railway hybrid power quality conditioner (HPQC) is one of the newly proposed devices for power quality compensation in co-phase high-speed traction power supply for its benefit in reduction of operation voltage over conventional railway power quality conditioner (RPC). However, initial railway HPQC design is developed based on minimum operation voltage at predefined fixed rated load. This may not be applicable in practical condition when load varies. In order to solve this problem, a railway HPQC design with increased operation voltage has been investigated to enhance the compensation capability. Nevertheless, the compensation capability is even larger than that required during load variations such that the operation voltage is higher than it actually requires. A lower operation voltage can actually be used to provide required compensation capability when the coupled impedance is different from the designed rated one. In this paper, the effect of coupled impedance on the compensation capability in co-phase railway HPQC is being analyzed. An impedance-mapping design technique based on required compensation capability is then proposed based on the analysis. The proposed method is advantageous for lower operation voltage and smaller capacitance value. The effectiveness of impedance-mapping technique is verified via simulation and experimental results. [ABSTRACT FROM AUTHOR]

Hybrid Railway Power Quality Conditioner (HPQC) is newly proposed for its effective reduction in dc-link operation voltage while providing similar power quality compensation in cophase traction power supply compared to conventional railway power quality conditioner. However, reduction in HPQC operation voltage limits its power quality compensation capability. For instance, the previously proposed HPQC design based on minimum operation voltage under fixed rated load has minimum power quality compensation capability. Under practical conditions when load varies, the required HPQC active and reactive compensation power also changes. The dc-link operation voltage of HPQC may therefore need to be enhanced to increase its power quality compensation capability. Therefore in this paper, the relationship between dc-link voltage of HPQC and its power quality compensation capability, as well as its limitations, are being analyzed. Simulation and experimental results are also presented to verify the mentioned relationship via investigations of system performance under different loading conditions. The research can provide a guideline for determination of HPQC operation voltage when load varies. [ABSTRACT FROM PUBLISHER]