Development of Small-scaled Converter for ITER Power Supply

In this paper, the small-scaled converter of High current magnetic power supply is designed for superconductor coil of Tokamak with controller with DSP-based controller. The small-scaled converter is composed of parallel and series structure with 4 quadrant converter. In order to verify AC-DC convector's characteristic, resistor load test has been done and prove stability of a power stack and controller. Exchange a resistor load to reactor load to test current control characteristic. And than adjust PI gain of controller repeatedly to follow reference current (10∼30[A]), set up the optimum gain value. When the sign of current reference changes from positive to negative or vice versa, thyristor firing must be delayed until feedback current is zero. So zero-crossing has dead-time, it was confirmed through experiment. The bypass is to provide the protection of converter and magnet, in fault condition that come from converters or magnets. In case of fault, the converter bypass shall be first activated to avoid DC short. Among converter bypass, external bypass switch test that is divided into two: One is bridge terminal bypass method and the other is converter terminal bypass method have been conducted to verify the performance. All above mentioned experiment get accomplished by both parallel and series structure