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This paper discusses a circuit configuration for a single-phase current source inverter that features power decoupling capability. This converter consists of a resonant type isolated DC/DC converter, power decoupling circuit, and a current source inverter (CSI). The proposed converter can be achieved the low input voltage ripple without a large smoothing inductor or electrolytic capacitor. In this...
Hybrid electromagnetic interference (EMI) filters (HEFs) which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode...
In this paper, a cost-effective single-phase bidirectional active-filter-integrated AC/DC converter is proposed. It provides simultaneous functions of power factor correction (PFC), DC voltage regulation and active power decoupling for mitigating the low-frequency DC voltage ripple, without an electrolytic capacitor and extra power switches. Such a converter is readily available from a conventional...
In this paper, a control scheme to improve load sharing among inverters of different power ratings in an ac microgrid is proposed. The proposed control scheme shapes the output impedance of the inverters independent of the voltage controller parameters and minimizes the requirement of the virtual impedance for proper load sharing. Results show that system stability improves. Simulation and experimental...
“Power Semiconductor Filter (PSF)” utilizes power semiconductor devices to eliminate the input current harmonics of switched-mode power converters. The concept is based on using a series pass device (SPD), which acts as a controllable current source, to program the input current waveform of the converter. The quiescent point of the SPD is stabilized at the boundary between the linear and saturation...
This paper investigates the application of an improved Modulated Model Predictive Control strategy to active power compensators. The proposed control is able to retain all the advantages of a Finite Control Set Model Predictive Control whilst improving the waveform harmonic spectrum. In fact a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included...
This paper proposes a hybrid DM Electromagnetic Interference (EMI) input filter model for AC-DC converters. After briefly reviewing DM EMI noise model for AC-DC converters, a closed loop filter model is developed. Based on the closed loop model, the open loop characteristics required for active filter's stable operation is determined. The constraints and requirements for the efficient implementation...
This paper presents LCL-filter configurations for parallel connected grid inverters. Three different configurations can be used in an LCL-filter implementation. All of these can be dimensioned to produce the same harmonic attenuation. However, the filter resonance frequencies and how they vary with respect to the number of inverters differs between the configurations. This paper presents and analyses...
The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback active damping would however demand a noise-sensitive derivative term. A digital realization of this derivative...
Cascaded converters are generally used for Medium Voltage (MV) grid connected applications due to the limitation in the voltage rating of available Silicon (Si) power devices. These converters find application in Active Power Filters, STATCOM or as Active Front End Converters for Solid State Transformers at the distribution voltage levels. The wide bandgap semiconductor devices have enabled the grid...
This paper presents a current dependent droop control method for equal load sharing of parallel connected inverters without any communication between them. Voltage droop in d and q axis voltage is achieved by using d and q axis currents. Each inverter works on voltage controlled mode where it controls the filter capacitor voltage. The outer voltage control loop generates current reference for filter...
In open-end winding AC motor drives, terminals of stator phases are normally connected between two inverters, normally, of the same type and size. In the present paper, an alternative configuration is studied where the machine is supplied exploiting two different converters: a main multi-level inverter and an auxiliary two-level inverter. The last operates as active power filter in order to eliminate...
The aim of this paper is to introduce a methodology to design an active DM filter at the input side of AC-DC converters to cancel current ripples and DM EMI noise. The boost PFC AC-DC converter's noise characteristic was first analyzed. The active filter topologies are designed based on the identified characteristics of the AC-DC converters. Several design issues such as thermal run away, DC offset,...
In this paper a new active output filter” (AOF) for variable speed constant frequency power system in aerospace applications is proposed. The proposed AOF is envisioned as a power semiconductor filter block. In the proposed system the passive L-C output filter components are replaced by an H-bridge. The H-bridge is operated at high frequency to inject voltage harmonics to achieve a sinusoidal output...
To address the generation uncertainty problems introduced by renewable energy power plants, STATCOMs are a typical solution to smoothen the point of common coupling (PCC) voltage in order to facilitate the integration of the renewables. A recently proposed control method — virtual synchronous machine (VSM), which controls grid-interfaced inverters to behave like synchronous machines so as to be more...
Detecting the load currents is a basic control method of paralleled active power filter (PAPF). The stability and compensation effect of the system would be influenced by the interactions of the load, weak grid and the paralleled active power filter (PAPF), when the load can't be equivalent to an ideal harmonic current source. The impedance models are established to analyze the stability of the system,...
In electrified vehicles, distinct harmonic currents and corresponding ripple voltages exist mainly on the DC-links of the traction inverter and single-phase high voltage (HV) battery charger. Those harmonic currents are normally filtered by a bulk capacitor or an additional active filter (AF) circuit. This presents an obstacle for improving the power density as well as reducing the cost. This paper...
Diode rectifier front ends with large DC bus capacitors used in Variable Frequency Drives (VFDs) draw discontinuous current from the power system resulting in poor input power factor and high input current distortion. In case of single-phase AC to DC rectifiers, the single-phase boost converter is popular and effective in improving the input power factor and reducing the input current harmonics. However,...
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