Instantaneous Pulse Pattern Control of Three-Phase Multi-Active Bridge DC-DC Converters

A three-phase multi-active bridge (MAB3) converter is a multiport dc-dc converter for high power applications. Its three-phase multi-winding transformer enables flexible power flow between multiple dc sources, offering superior high power density and efficiency. However, when fixed duty cycles are employed with mismatched dc voltage conditions, the efficiency of the MAB3 deteriorates, particularly in light-load conditions. To address this, modulation schemes with variable duty cycles are needed, along with dynamic control. However, few studies have explored dynamic control methods compatible with such multi-variable modulations. Without proper dynamic control, step changes in voltage patterns can induce transient overcurrents and transformer flux saturation, limiting the achievable power slew rate. Consequently, mitigating this poor dynamic performance may necessitate transformer overdesign or larger DC-link capacitance. To overcome these challenges, this article proposes an instantaneous pulse pattern control (IPPC) to support generic modulations of MAB3 converters. By formulating dynamic control as a multi-flux regulation problem, the IPPC enables to accommodate the generic modulation schemes while achieving consistent and minimized transient times. Experimental results demonstrate that the proposed IPPC consistently reduces transient times to a single sampling period, equivalent to one sixth of the switching period.