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Isolated AC/DC matrix converter can realize AC-DC conversion with high frequency transformer to isolate the AC and DC side. Thanks to its high-power density and high efficiency, it is an attractive alternative to the conventional voltage source converter in hybrid microgird as interlinking converter, which adopts power frequency transformers when isolation is required. To realize this, bi-directional...
The appearance of harmonics in the grid voltage is an issue for the generation systems and grid connected consumers. This paper presents the basic control strategy to be implemented in Synchronous Power Control (SPC) based power converters, which contributes to reduce the harmonic content in the voltage by means of injecting different harmonic current to the grid using a separated virtual admittance...
Capacitor-current-feedback active damping method is commonly used in LCL-filtered grid-connected inverters, which attenuates the resonance peak by emulating a virtual resistor in parallel with the filter capacitor. Taking the digital control delay into account, the emulation component becomes frequency-dependent, and it will turn negative when the filter resonance frequency becomes higher than one-sixth...
In this paper, a novel effective duty cycle method is introduced to predict the RMS and average current for power components in discontinuous conduction mode (DCM) AC-DC boost power factor correction (PFC) topologies. The proposed model can be used for power component conduction losses estimation. The RMS current and average current of power components are derived. PSIM simulation and experimental...
Conventional permanent magnet (PM) machine open-phase fault detection relies on the estimation of current harmonics using existing drive current sensors. Because the magnitudes of current harmonic are proportional to the machine load condition, it is still a challenge to detect a phase fault at light load when fault induced current harmonics are too small to estimate. This paper investigates the phase...
Since the capacitor equivalent series resistance (ESR) above 1kHz almost stays constant, dc-link current root-mean-square (RMS) closed form equation is an easy way to evaluate the capacitor losses from the switching harmonic currents (SHCs). But when the ac current contains multiple low order harmonics (LOHs), their impacts on the dc-link has not been systematically studied. In this paper, a straightforward...
In this paper a control system for shunt active power filters based on an array of proportional-resonant regulators is developed. An important advantage of this topology is the possibility of selective control, namely the possibility to choose the set of current harmonics that has to be compensated. The main contribution of the paper is an algorithm that adaptively changes the voltage saturation of...
This paper proposes a hypothetic silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) power module for the medium voltage (MV) variable frequency drive (VFD). A peer-to-peer comparison between commercial silicon (Si) insulated-gate bipolar transistor (IGBT) and the proposed SiC MOSFET module results in some promising results to support the introduction of SiC power modules...
This paper presents a high efficiency SiC power converter in pulsed power applications. SiC Power MOSFETs have 7∼10 times lower switching loss than Silicon counterparts. However, because of the large depletion capacitance, the SiC device switching loss will be higher than silicon device at zero current. Therefore, loss reduction method is proposed to further improve SiC gradient driver efficiency...
Buck and buck-boost ac-ac converter topologies with a center-point-clamped circuit configuration have been recently reported in literature. These converter circuits reduce the voltage stress on the bidirectional switches employed in corresponding direct ac-ac converters. This new topological structure enables access to the mid-point of voltage terminals. This paper introduces a family of such ac-ac...
Modular multilevel converters (MMC) are emerging to be an alternative approach for realizing power converters for a variety of high power applications because they allow series-cascaded levels and/or parallel-connected branches. However, the design of communication interface between system controller and individual modules became increasingly complicated as more modules been added into the system,...
This paper presents a novel control method that enables operation of Modular Multilevel Converters under non-sinusoidal AC supply conditions based on frequency domain decomposition of supply voltages. The proposed control method enables to inject or draw near sinusoidal grid currents even during the presence of harmonic distortions in the supply voltages without the use of additional hardware filters...
This paper presents a unified selective harmonic compensation strategy using DG-interfacing inverter with LCL filter in the presence of nonlinear local loads for both grid-connected and islanded microgrid. Compared with the existing harmonic compensation methods in the literature, the proposed strategy consists of a triple-control-loop in the grid-connected mode to compensate the grid current harmonics...
A photovoltaic (PV) generator is one of the primary power sources in a DC micro-grid (MG). The power generated by PV systems may inject high-order transient harmonics and low frequency ripple into the DC MG, especially if a conventional widely used Perturbation and Observation (P&O) maximum power point tracker is employed. In this paper a novel active filtering approach is proposed to improve...
A novel control strategy which enables proportional linear and nonlinear loads sharing among paralleled inverters and voltage harmonic suppression is proposed in this paper. The proposed method is based on the autonomous currents sharing controller (ACSC) instead of conventional power droop control to provide fast transient response, decoupling control and large stability margin. The current components...
This paper presents dynamic analysis of a Modular Multi-Parallel Rectifier (MMR) based on state-space modelling. The proposed topology is suitable for high power motor drive or multi-parallel AC-DC applications, which can reduce line current harmonics emissions significantly. However, a proper controller is required to share and control current through each rectifier. Mathematical analysis and simulations...
The grid inductance is a sensitive parameter to be considered in order not to degrade the control system performance and to guarantee the system stability. In this paper, the Grid Inductance estimation based on Generalized Integrators (GIGI) method is proposed. It carries out an online grid inductance detection, which disturbs the grid by injecting a time-limited and small-amplitude harmonic voltage...
This paper presents a harmonic suppression control strategy under unbalanced point of common coupling (PCC) voltage for modular multilevel converter based shunt active power filter (MMC-SAPF). Harmonics are extracted by multiple synchronous reference frame (MSRF) algorithm to generate the compensation current references of positive- and negative-sequence control for MMC-SAPF. The proposed independent...
For the control of electric motors, conventional inverters have utilized position and current sensors, but they undesirable in terms of cost and maintenance effort. For this reason, approaches without the sensors are developed by applying back electromotive force or signal injection-based method which also has some problems related to the the deterioration of control performance in low speed range...
This paper proposes a capacitor-less inverter for AC motor driving system. The proposed converter consists of a single-phase diode rectifier, a small film capacitor at the DC bus, a three-phase voltage-source inverter, and a permanent magnet synchronous motor (PMSM). Since the DC bus capacitor is quite small, the input current of the AC source will be affected directly by the three-phase inverter...
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