Modelling and Control of a Dual Active Bridge Applied to an Uninterruptible Power Supply

Abstract:
Uninterruptible power supply (UPS) systems place high demands on the dynamic behavior of the power electronics. A key component of a UPS is the DC-DC converter. The DC-DC converter must be bidirec-tional and meet high dynamic requirements. The voltage source is typically a lithium-ion battery. In order to extend the lifetime of the battery, a current filter is required. This paper proposes a new control strat-egy for a DC-DC converter with Dual Active Bridge (DAB) topology, to meet the dynamic requirements of the UPS. The proposed controller is an I-controller that can be tuned in the time domain. To obtain a stable control system, the presented modelling technique also includes the current filter as well as the battery. The non-linear characteristics of the DAB are linearized with the inverse transfer characteristic of the DAB.