This paper presents a comprehensive analysis of single-phase full-bridge asymmetrical flying capacitor inverters under distinct capacitor voltage values. The asymmetrical operation is explored in order to increase the number of output levels for the same number of semiconductors. A formation law for the flying capacitors voltages is proposed according to the desired number of output levels. The voltage balance of the flying capacitors is carried out using the charge balance analysis. The modulation strategy is also verified to overcome the inverter unbalance problem. Simulation and experimental results are included to demonstrate the performance of the proposed structures.

This paper proposes a single-stage AC-DC rectifier with power factor correction (PFC), high-frequency isolation and bidirectional power conversion capability for on-board battery charger (OBC) applications. The proposed converter is based on the interleaving technique and the Dual Active Bridge (DAB) operation, applying the phase-shift control to regulate the power flow. In addition to topology, this article presents a control strategy for reducing low-frequency power ripples transferred to the secondary side without any additional component and hence maintaining overall size and cost. The single-phase OBC can interchange active power with the grid to charge batteries while performing grid-to-vehicle (G2V) functionality or transferring energy back to the grid via vehicle-to-grid (V2G) mode. The theoretical analysis of the converter including modulation strategy and feedback control scheme are presented. The proposed topology and control strategy have been verified by experimental results of a 650 W SiC-based prototype.

In this paper, a generic complex repetitive controller (nk + m RC, k$\times$Z), based on the inverse transfer function of the generalized delayed signal cancelation transformation is proposed. The presented complex controller can be designed for regulating different positive- and negative-sequence harmonic components through a space-vector error signal, with improved response time as compared to traditional repetitive controllers. An evaluation of the proposed control scheme stability, based on phase margin, Nyquist diagram and sensitivity function is presented. The effects of the controller parameters on the system's stability and also on its dynamic response are shown and allow the definition of some control design guidelines. Experimental results are presented to validate the theoretical assumptions through applying the proposed controller for regulating the currents in a three-phase active power filter.

This paper analyzes, designs and implements a reconfigurable phase-shifted full-bridge (PSFB) converter. It adopts the topology of the traditional PSFB converter and incorporates clamping circuits to solve some fundamental problems of conventional topology. In addition, auxiliary switches are employed for output reconfiguration, which allows expanding the output voltage range without compromising the system efficiency. Single pole double throw (SPDT) mechanical switches are used to realize series and parallel connections. In this paper, the characterization of the PSFB converter with clamping circuit and its design considerations are discussed. A 10 kW prototype with a power density of 0.485 W/cm³, 900 V input voltage and 400/800 V nominal output voltage was manufactured. The experimental results validated the analysis and confirmed the high conversion efficiency for a wide load range; an efficiency of 96.69% was obtained for the full load condition.

This paper proposes a high-efficiency step-down dc-dc converter with limited touch current and voltage gain equivalent to the conventional buck converter. By including a capacitive coupling cell it is possible to reduce touch currents, presenting a higher safety degree against electric shocks. The main operating stages and equations describing the proposed converter are presented. The capacitive coupling cell operates through the resonant switched-capacitor principle and the impact of the parasitic elements is evaluated. Even though it has a resonant stage, the converter operates with a fixed switching frequency, simplifying the control scheme. A design guideline based on the converter specifications and safety criteria is presented. Simulation results are included to compare the touch current generated by the proposed converter and that of the conventional buck converter, demonstrating the effectiveness of the proposal. Experimental results for a 3 kW prototype operating at 180 kHz switching frequency are presented, including waveforms of main components, closed-loop control performance and efficiency curve, with a peak around 97.8%. An experimental evaluation comparing the proposed converter and the LLC half-bridge converter is also performed. Finally, the touch current tests demonstrated that the risk is automatically eliminated by the proposed converter in approximately 60 ms.