The power supply system of the Dynamic Ergodic Divertor at TEXTOR-94

The Dynamic Ergodic Divertor (DED) consists of four sets of coils on the inboard side of the TEXTOR-94 vessel, each with four helical conductors. The coil sets will be energized by DC or by 4-phase current at selected frequencies up to 10 kHz with amplitudes up to 15 kA. Power supply units of 750 kW feeding two coils each are foreseen. The modular design allows for different patterns of current distribution. The maximum operating frequency led to the choice of IGBT inverters. At AC operation the reactive load will be compensated by capacitor banks connected in series to the load thus forming resonant circuits. Matching transformers are necessary to match the voltage level of IGBTʹs to that of the load at maximum output power. All load units are inductively coupled resulting in a power transfer between the load units. An additional de-coupling transformer compensates the coupling. A central control unit co-ordinates the feedback control of current amplitudes and of the mutual phase shifts of all power supply units.