Alexis A. Gómez

This paper explores control strategies based on variable switching frequency for the Single Active Bridge converter to expand its soft-switching capabilities without additional components. While the conduction mode and the soft-switching features of this converter can be maintained across the entire operational range using variable switching frequency with a constant duty cycle, this work demonstrates that the use of both as control variables provides additional degrees of freedom to optimize performance. Specifically, two control trajectory selection criteria are proposed: one focused on minimizing the switching frequency range while reducing rms currents, and another aimed at maintaining constant recirculating current to ensure adequate ZVS across all operating points. Additionally, comprehensive design guidelines that integrate both control variables are provided. The proposed strategies and design methodologies are validated through a comparative experimental analysis of four 800 V to 400 V, 2.2 kW prototypes, each designed for the same specifications and utilizing a different control strategy.

This study conducts a comparative analysis of the Threshold Voltage (V_th) degradation in Silicon Carbide (SiC) MOSFETs subjected to various dynamic tests in accordance with industry guidelines. To ensure a fair comparison, a custom experimental setup is employed. The observed degradation outcomes show variability depending on whether high voltage levels were applied, driving conditions or switching events occurrence. A comprehensive explanation of the experimental observations is provided by means of Finite Element Method (FEM) simulations and parasitic capacitances analysis. Furthermore, the study introduces a conceptual framework and methodology facilitating the emulation of high-voltage aging effects through simplified degradation test procedures.

Electric vehicles (EVs) are a sustainable means of transportation, with their onboard batteries being crucial for both performance and energy management. A modular and reconfigurable power converter topology to connect removable batteries to the main DC bus of an EV is proposed in this paper. By employing Dual Active Bridge (DAB) converters in an Input Parallel Output Series (IPOS) configuration, the proposed topology is compatible with 400 V and 800 V standards without the need for external switches. The research explored the possibility to apply a very simple control strategy based on independent linear regulators. A theoretical analysis of the IPOS DAB converter is presented and the design of independent control regulators which minimize the coupling effect between the control variables is addressed. The stability of the IPOS DAB converter could be ensured using the proposed simplistic approach, enabling us to drastically simplify the regulator design step. The dynamic performance of the system was confirmed by means of a simulation and experimentally.

In this article, a thorough study of the dynamic behavior of the single active bridge (SAB) converter is presented. The SAB converter can be considered a unidirectional version of the dual active bridge (DAB) converter, which has been extensively analyzed in recent years. However, the dynamics of the SAB converter differs from the one corresponding to the DAB converter and has not been addressed so far. The SAB converter can operate in two different conduction modes, namely discontinuous conduction mode (DCM) and continuous conduction mode (CCM). The SAB operating in DCM presents the same static and dynamic behavior as the phase-shifted controlled full bridge (PSFB) converter if the value of the inductor of the SAB is the same as the value of the output inductor of the PSFB referred to the transformer primary side. However, the dynamic behavior of the SAB converter in CCM is different and must be analyzed in detail. As a result of the analysis carried out, average small-signal linear models have been obtained for both conduction modes. These models are compared with the ones obtained for other similar converters and they have been validated with simulation and experimental results.