Multilevel Active Bridge (AB)-based converters are potential candidates for DC applications due to their ability to integrate multiple sources while minimizing volume. This paper presents an analytical and simulation-based investigation of circulating current behavior and power factor performance in AB-based multilevel converter structures. A High-Frequency Link (HFL) analysis framework is developed to characterize voltage, current, and power transfer waveforms, providing insight into reactive power generation and its impact on overall efficiency. By introducing a modulation-based control approach, the proposed converters significantly reduce circulating currents and enhance the power factor, particularly under varying phase shift conditions. Compared to conventional Quadruple Active Bridge (QAB) topologies, the discussed multilevel architectures offer reduced transformer complexity and improved power quality, making them suitable for demanding applications such as electric vehicles and aerospace systems.

Proportional-resonant and repetitive controllers are widely used for grid current control in single-phase grid-connected inverters. This paper presents a comparative study of the performance of these two controller types in mitigating low-order harmonics with a descriptive analysis of their design. Moreover, low-order harmonics arising from the dead time in single-phase highly efficient and reliable inverter concept (HERIC) are investigated. Then, a novel scheme based on the harmonic decoupling network and second-order generalized integrator is designed to extract the low-order harmonics from the grid current. These extracted components are subtracted from the reference current to efficiently attenuate the low-order components. Experimental studies show an efficient mitigation of the low-order harmonics with the proposed scheme.

This paper introduces a new soft-switched high gain converter topology with Input Current Smoother (ICS) capability to mitigate Normalized Peak Inverse Voltage (NPIV). By employing soft switching techniques, the converter achieves significant reductions in switching losses and improved overall efficiency, making it ideal for high-frequency applications. The proposed converter enhances voltage gain while minimizing voltage stress on power semiconductors, overcoming the limitations of conventional step-up converters. The paper provides a detailed description of the converter's operation principles, configuration, and steady-state analysis. Performance comparisons with existing topologies demonstrate superior voltage gain, minimized voltage stress on semiconductors, negligible input current ripple, and remarkable efficiency. Finally, simulation results demonstrate the advantages of the proposed converter by using PSCAD software.

Voltage spikes during the switching transients play an important role in determining the power losses in hard-switching converters. These spikes are functions of several factors at the instant of switching such as DC-link voltage, load current, transistor and diode switching delay times, reverse recovery current of the diode, parasitic capacitance and inductance of the circuit. This paper introduces a numerical approach to accurately model the switching power losses of a single-phase H-bridge (SPHB) inverter. The data required to obtain the equivalent resistance is extracted from the experimental double-pulse tests (DPTs). Then, the concept of local and global rms currents is considered to incorporate the effect of pulse width modulation (PWM) in the estimation of the switching losses. The results are computed for unipolar and bipolar PWM schemes. Finally, the reflection rule is utilized to obtain an equivalent output resistance for the inverter switching losses.