Improved Instantaneous Current Control for High-Power Three-Phase Dual-Active Bridge DC–DC Converters

With the increasing share of renewable and decentralized power sources, the need for power electronics and especially for efficient high-frequency 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 is easy to implement and gives excellent results for transformers with a high transient time constant, i.e., low winding resistance. However, the method can be improved for transformers with increased winding resistance. This paper suggests two approaches that reach steady state in one-third of a switching period and half a switching period, respectively. Independent of the winding resistance, the suggested control schemes give superior results and oscillations of the dc current are completely eliminated. The control schemes are investigated in detail and derived mathematically. These exact solutions are linearized for ease of implementation in digital control circuitry. Simulations and an experimental verification on a laboratory prototype confirm the outstanding performance of the developed approach.