A current controller device (43, 430) using a vector control algorithm for controlling conversion of DC power into AC power and/or vice versa by a converter, the controller device having an open loop control loop gain and comprising: - a first current demand input for receiving a first current demand signal (IQ_NET*); - al least a second current demand input for receiving a second current demand signal (ID_NET*); - a first current feedback input for receiving a first current feedback signal (IQ_NET) representing an AC current of the AC power; - a second current feedback input for receiving a second current feedback signal (ID_NET) representing an AC current of the AC power; - a first voltage feedback input for receiving a first voltage feedback signal (VQ_NET) representing an AC voltage of the AC power; - a second voltage feedback input for receiving a second voltage feedback signal (VD_NET) representing an AC voltage of the AC power; - a first voltage demand output for outputting a first voltage demand signal (VQ_NET*); - a second voltage demand output for outputting a second voltage demand signal (VD_NET*); and - a controller for producing said first voltage demand signal (VQ_NET*) and said second voltage demand signal (VD_NET*) on the basis of said first current demand signal (IQ_NET*), said second current demand signal (ID_NET*), said first current feedback (IQ_NET), said second current feedback (ID_NET), said first voltage feedback (VQ_NET) and said second voltage feedback (VD_NET), where the open loop control loop gain depends on the frequencies contained in the first and second current feedback signals (IQ_NET, ID_NET), characterised in that a first filter is provided at the first current feedback input and a second filter is provided at the second current feedback input, which first and second filters (65, 67) each having a filter characteristics chosen such as to reduce frequencies of the first and second current feedback signals (IQ_NET, ID_NET) at which the frequency dependent open loop control loop gain would become greater than unity and would have a phase less than or equal to minus 180°. - a first current demand input for receiving a first current demand signal (IQ_NET*); - al least a second current demand input for receiving a second current demand signal (ID_NET*); - a first current feedback input for receiving a first current feedback signal (IQ_NET) representing an AC current of the AC power; - a second current feedback input for receiving a second current feedback signal (ID_NET) representing an AC current of the AC power; - a first voltage feedback input for receiving a first voltage feedback signal (VQ_NET) representing an AC voltage of the AC power; - a second voltage feedback input for receiving a second voltage feedback signal (VD_NET) representing an AC voltage of the AC power; - a first voltage demand output for outputting a first voltage demand signal (VQ_NET*); - a second voltage demand output for outputting a second voltage demand signal (VD_NET*); and - a controller for producing said first voltage demand signal (VQ_NET*) and said second voltage demand signal (VD_NET*) on the basis of said first current demand signal (IQ_NET*), said second current demand signal (ID_NET*), said first current feedback (IQ_NET), said second current feedback (ID_NET), said first voltage feedback (VQ_NET) and said second voltage feedback (VD_NET),