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This paper proposes a new inverter topology based on the active neutral-point-clamped (ANPC) converter with capability to integrate one energy storage system (ESS) per inverter leg with an independent state of charge control, so that each inverter leg has two dc ports and one ac port. The primary dc port is common to all inverter legs and it is connected to the main power source. The secondary dc port is suitable for ESS connection because of its two-quadrant operation, with bidirectional current capability, so that the ESS can be charged and discharged with regulated current. Integration of a secondary dc port with independent control also allows the use of different ESS technologies for each inverter leg to compose a hybrid ESS. Redundant switching states of the proposed structure are used to balance the energy exchanged between the secondary dc port and the dc bus capacitors. Theoretical propositions were experimentally validated through a 1-kW single-phase inverter with a secondary dc port connected to a 230-V ESS and ac port connected to an LC filter feeding a linear load. Low total harmonic distortion (THD) sinusoidal current is generated at the ac port while charging or discharging the ESS with a constant current. [ABSTRACT FROM AUTHOR]

This paper proposes a new grid current controller for a photovoltaic (PV) module integrated buck inverter using a single pulsewidth modulation switch and an unfolding H-bridge, which significantly reduces switching losses. To achieve this, an internal grid current loop with active damping is presented with an LCL filter to connect it to the utility grid. The problem of the filter natural resonance is solved by means of a virtual impedance (active damping), demanding no additional sensor. Experimental results obtained from a 200-W prototype achieved a European efficiency of 96.27% with a current total harmonic distortion of 3.7%. [ABSTRACT FROM AUTHOR]

Series active power filters (APF) are an important solution to deal with power quality issues in weak grids under the presence of non-linear loads. The use of voltage feedback from the critical-load-bus (cload-bus) in the series APF allows for a control strategy that has performance and processing power advantages, when compared to other strategies in literature, but can cause saturation of injection transformers. This paper presents a control strategy that uses cload-bus voltage feedback with an additional control loop of the dc current in the output of the series APF voltage source converter (VSC), to avoid injection transformer saturation. The controlled dc current is additionally used for balancing the split dc-bus capacitors voltage in the VSC. The series APF and the proposed control strategy are modeled using small signal analysis for allowing controller design. Experimental results from a 3 kVA prototype are presented, with cload-bus voltage total harmonic distortion improving from 9% to 3% in each phase, while achieving the objectives of improved cload voltage waveform, controlled transformer dc current, and balanced dc-bus capacitors voltage. [ABSTRACT FROM AUTHOR]

Power supplies have played crucial role to improve and extend plasma applications. Several dc, pulsed, and radio frequency (RF) stabilized power supplies have been developed over a wide range of frequencies and voltage waveforms. However, the influence of voltage waveform on the plasma densification, mainly due to the secondary electrons emission from the electrodes, has not been quite explored. This paper proposes an asymmetric pulsed bipolar power supply, adjustable in frequency, amplitude, pulsewidth, and number of pulses for generation of cold plasmas. Short period positive pulses, between longer negative pulses, increase greatly the secondary electron emission from the electrodes and, consequently, the plasma ionization rate. Short pulses (ns) are obtained by the phase shift between each carrier, and the high-intensity pulses are obtained by cascading the cell submodules in a half-bridge cascade topology, using a modular half-bridge converter configuration. The intensity of the positive and negative pulses can be varied independently. There is no unintended dc voltage level between the electrodes, which appear in RF plasmas. The plasma generated in this way is free of electric arc and can be kept stable within a broader range of operating parameters, mainly the voltage and the working gas pressure. [ABSTRACT FROM AUTHOR]

This paper presents a simplified control technique for a dual three-phase topology of a unified power quality conditioner—iUPQC. The iUPQC is composed of two active filters, a series active filter and a shunt active filter (parallel active filter), used to eliminate harmonics and unbalances. Different from a conventional UPQC, the iUPQC has the series filter controlled as a sinusoidal current source and the shunt filter controlled as a sinusoidal voltage source. Therefore, the pulse width modulation (PWM) controls of the iUPQC deal with a well-known frequency spectrum, since it is controlled using voltage and current sinusoidal references, different from the conventional UPQC that is controlled using nonsinusoidal references. In this paper, the proposed design control, power flow analysis, and experimental results of the developed prototype are presented. [ABSTRACT FROM PUBLISHER]

This paper presents the dynamic modeling and digital control of a single-stage isolated current rectifier with power factor correction based on the integration of full-bridge and flyback converters. This converter is designed to operate with adjustable output voltage so that it can operate in two distinct operation modes, depending on the input and output voltages. Therefore, small-signal state-space average models are obtained for the converter operating in step-down and step-up operation modes, and analysis and design of the digital control system are included for different operating points. Experimental results based on a 3-kW prototype are presented to validate the proposed control system under distinct conditions. [ABSTRACT FROM PUBLISHER]

This paper proposes an energy regeneration circuit for three-phase voltage-fed inverters using a modified Undeland snubber. The proposed system uses a quasi-square-wave zero voltage switching dc–dc auxiliary converter to regenerate the energy from snubber capacitor to the dc bus. The regenerative circuit uses a single active switch, and it operates independently of the three-phase inverter. Operation stages, theoretical waveforms, and a design methodology are presented. Experimental results based on a 4.5-kVA three-phase inverter prototype are included to validate the proposed topology. [ABSTRACT FROM PUBLISHER]

This paper presents a regenerative step-up/step- down dc-dc zero-voltage-switching pulsewidth-modulation converter with active clamping. The switch losses are reduced due to the implementation of a simple active snubber circuit that provides soft commutation in all the switches of the converter. The theoretical analysis, basic equations, design methodology, and experimental results are shown in this paper. A control methodology to assure the output voltage regulation is also proposed. The main advantages of the proposed power converter are the small number of components, simplicity of the controller, robustness, small weight and size, and high efficiency. [ABSTRACT FROM AUTHOR]

This paper presents a zero-voltage (pulsewidth modulation) half-bridge inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power applications. Switching losses are reduced due to implementation of the simple active snubber circuit that provides zero-voltage-switching conditions for all switches, which includes the auxiliary one. Its main features are simple modulation strategy, robustness, low weight and volume, low harmonic distortion of the output current, and high efficiency. The principle of operation for steady-state conditions, mathematical analysis, and experimental results from a laboratory prototype are presented. [ABSTRACT FROM AUTHOR]