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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...
Resonant filters can be beneficial for significant reduction of the filter size in buck converters. Compared to the conventional low-pass filter, the resonant filters can be designed to provide high attenuation to the ripple components near the pulse width modulation (PWM) switching frequency resulting in much smaller filter components. In traditional resonant filter, the high attenuation at a specific...
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...
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...
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...
The control of the grid side current in an LCL filter based grid connected converter is generally complex and involve multi loop structure. This paper presents a method to control the grid current indirectly by controlling the converter side current with compensation of the filter capacitor current. The proposed control algorithm uses only one current sensor to measure the converter side current....
This paper presents the analytical design procedure to select the inductance and the capacitance values of both the input and output filters for the 5-Level three-phase Back to Back E-Type Converter (5L3Φ BTB E-Type Converter). The 5L3Φ BTB E-Type Converter is used to accomplish the double conversion AC-DC/DC-AC in applications which include variable speed industrial electric drives and the interfacing...
The star-configured modular multilevel converter is a promising topology for grid-connected storage as well as power-quality applications and motor drives. During operation, the ac output power generates substantial current pulsation at twice the output frequency in the modules, which causes additional loss and requires an increase of the module capacitance. This paper presents a common-mode voltage...
The multiobjective allocation optimization of single tuned passive power filters for decreasing the power losses and harmonic mitigation in distribution networks is presented in the paper. The Pareto definition of the multiobjective problems is used in the paper. The two objectives problem consists of the two technical objective functions, the real power losses and the total harmonic distortion, is...
The active or passive decoupling method has to be utilized to deal with the second-order harmonic existing in the DC-bus of the grid-tied single-phase inverters. Compared with the active decoupling method, the passive decoupling method is simpler, cheaper and more reliable. The electrolytic capacitors are usually used in the DC-bus as typical passive decoupling components. The film capacitors can...
AC-DC single-stage converters are widely used in industrial applications because they are cheaper than conventional two-stage converters. In this paper, state of the art low power single-stage converters are reviewed. These converters are classified into several types in the paper, the operation of an example converter of each type is discussed, and the advantages and drawbacks of each type are stated...
This paper analyzes a new architecture of the AC/DC type power supply for data centers. The source cumulates the following functions: three-phase current rectification, transformation of voltage parameters and DC voltage stabilization. The source ensures the reactive power compensation and does not distort the currents in the power three-phase network. The transfer of power from the alternating current...
Paper deals with analysis and modeling of a new type of single-phase supplied single leg LC matrix converter (SLLC MxC) with two phase outputs. Its schematic arrangement consists of one-leg half-bridge matrix converter, network with a neutral point, LC filters, switched capacitor and passive or active load. As the harmonic analysis of the voltage of both phases gives a very high value of total harmonic...
This paper addresses calculation of current Total Harmonic Distortion (THD) for a three-phase two-level PWM inverter with an LCL-filter. Analytical approach introduced in late 1980s for a two-level inverter with inductance dominated load is generalized accounting for the smoothing effect of an LCL-filter. Though the obtained closed-form analytical solutions initially assume (infinitely) large ratio...
Capacitor-switching operation can be used to measure network harmonic impedance. Via the transient components of voltage and current after capacitor switching, the harmonic impedance of PCC (Point of Common Coupling) can be calculated. To improve measurement accuracy, the TLS-ESPRIT algorithm is introduced in this paper to filter out noise and fundamental components in voltage and current signals...
The paper presents the methodology and design of testing structure dedicated to one laboratory model of a filtering and regeneration system (SISFREG) developed through the project number 42/2014, type Partnerships — PCCA 2013, which allows the conversion of the dc traction substations in "active substations". The configuration was made based on the actual conditions prevailing in a substation...
An effective auxiliary flyback circuit to suppress voltage ripple is proposed and investigated in a single-phase isolated full-bridge boost power factor correction (PFC) converter, by which the output voltage ripple can be suppressed obviously. The output voltage ripple can be reduced by adding the auxiliary link using the absorbed energy from the voltage spike. The energy is controlled to be transferred...
At present, the field of power factor corrected (PFC) rectifiers are very much matured. Typically a single phase PFC converter requires measurements from three independent sensors i.e. input voltage, input current and output voltage. By considering a need of farther compact and more flexible in terms of input to output voltage gain, a new UPF rectifier with two buck-boost converter operating in interleaved...
Harmonic resonance problems can be aroused in the industrial power system in the presence of both nonlinear loads and shunt capacitors. This paper investigates the harmonic resonance problem by case-studying of a copper smelting plant low voltage power distribution system. A flexible selective harmonic compensation and resonance damping algorithm for shunt active power filter (SAPF) is proposed to...
Distribution grids unbalance challenges the DC-link of the Smart Transformer leading to higher ripples and then the lifetime of the DC aluminium electrolytic capacitors (AEC) is reduced. Additionally, dead time and nonlinearity characteristic of IGBT also may introduce ripple current in DC link, potentially decreasing the lifetime of AEC. Based on physical characteristic of AEC, the lifetime estimation...
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