Improved Instantaneous Current Control for the Three-Phase Dual-Active Bridge DC-DC Converter

With the share of renewable and decentralized power sources increasing, the need for power electronics and especially for efficient high-power dc-dc converters is expected to grow. The three-phase dual-active bridge is a promising technology, as it has a high power density and inherently features galvanic isolation. A highly dynamic method to control the current and thus the transferred power for this converter type has recently been published. The published approach gives excellent results for transformers with a high decay time constant. However, the method can be improved for transformers with significant influence of the winding resistance. The present paper suggests two exact approaches that reach steady state in one third and half of a switching period, respectively. Independent of the winding resistance, the suggested control schemes give superior results, oscillations of the dc current are completely eliminated. The control schemes are investigated in detail and proven mathematically in an elegant manner. Simulations and an experimental verification on a laboratory prototype confirm the outstanding performance of the developed approach.