Three-phase Dual Active Bridge DC-DC Research Articles

Minimum current stress control strategy for three degree of freedom three-phase dual active bridge DC-DC converter

Compared to single-phase dual active bridge (1p-DAB) DC-DC converters, three-phase dual active bridge (3p-DAB) DC-DC converters have advantages such as high single machine power, high power density, small filtering capacitance, and are more suitable for high-voltage situations. Therefore, they have good application prospects in DC transmission and industrial high-power DC-DC converters. However, under traditional single-phase shift (SPS) control, especially in the low power range, there is a large reactive current and severe soft switch loss. This article adopts an asymmetric modulation strategy for its larger reactive power, which reduces its reactive power in the low power range with more degrees of freedom and improves the efficiency of power transmission. Taking current stress as the optimization objective, the KKT algorithm is used to solve, and the corresponding analytical solution is ultimately obtained. Finally, a simulation is built by using MATLAB software to verify the feasibility of the proposed solution.

Analysis of the Transformer Influence on a Three-Phase Dual Active Bridge DC-DC Converter

In this work, the impact of the high-frequency transformer on the three-phase dual active bridge DC-to-DC converter operation is investigated, using four transformers with different connections: star-star, delta-delta, star-delta and delta-star. The main objective is to evaluate what is the transformer connection that allows the converter to be operated with high efficiency for different voltage conversion ratios and output power. The apparent power requirements of the high frequency transformers and the power semiconductors stress are evaluated, which allows obtaining the soft switching operating range for each transformer connection. The results of the analysis allow to select the most suitable transformer connection for each application.

Performance Evaluation of a Three-Phase Dual Active Bridge DC-DC Converter with Different Transformer Winding Configurations

This paper investigates the impact of three transformer winding configurations, i.e., the Y–Y, the Y– $\Delta$ , and the $\Delta$ – $\Delta$ configuration, on the performance of a three-phase dual active bridge (DAB) dc–dc converter. For each configuration, equations for the phase currents, power flow, and zero-voltage switching (ZVS) boundaries are derived for all possible switching modes of the three-phase DAB. Thereafter, a comparison is made of the stress on the switches, the transformer, and the filter capacitors for the selected winding configurations. The comparison reveals that the Y–Y and $\Delta$ – $\Delta$ configuration perform equally regarding above aspects, with the only difference of a lower winding current for the $\Delta$ – $\Delta$ configuration. The Y– $\Delta$ configuration shows a constant commutation current for phase-shifts from 0 to 30 degrees. Therefore, this configuration features a wider ZVS region for low output powers. Overall, the Y– $\Delta$ configuration performs best for power levels between 50% and 80%, regarding the stress on the switches, the transformer, and the filter capacitors. The theoretical analysis is supported with measurements obtained from a high-power experimental setup.