Transformers are used when galvanically isolated energy transfer, i.e. according to the European standard EN61558, is necessary. To guarantee the availability of copper for the next decades and to counteract the expected price increase, it is essential to find resource friendly alternatives.
Also the elimination of electrolytic capacitors makes it possible to reduce size and weight without sacrificing lifetime. The functionality of the one stage system is ensured with ohmic loads. The problem arises, when the converter enters reactive power operation, which produces a highly nonlinear shape of the control parameter. Therefore an extremely dynamic control scheme is essential in order to keep track of the control parameter. Furthermore, due to the low capacitance on the output of the converter, the power stage is highly unstable. In this thesis, the drawbacks of an AC-AC DAB converter under reactive power operation are described. Firstly the transfer functions of the control stages are measured and afterwards a current mode controller is implemented and optimized. Lastly the newly designed current mode controller is compared to a voltage mode control scheme and it is shown, that the bandwidth is increased. Therefore the proposed control scheme enhances the reactive power operation of a one stage AC-AC converter.