Search

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]