Assessment and Optimization of Output Filter for Microsecond Transient in PSM-Based Megawatt HVPS

Electron cyclotron heating (ECH) in nuclear fusion devices utilizes MW gyrotrons fed by high-voltage power supplies (HVPSs). HVPS with fast ramp up time of
$40 \mu \text{s}$
with overshoot < 2%, settling time better than
$20 \mu \text{s}$
, and ripple < 1% is a prerequisite condition. These high-power RF devices (gyrotrons) are very sensitive to overshoots and settling time of fast rising voltage pulses. The 6-MW, −55-kV pulse step modulation (PSM)-based HVPS at ITER-INDIA lab can cater simultaneous operation of two 1-MW gyrotrons. This megawatt HVPS has to support microsecond settling time along with performance parameters even with partial loading conditions of
$\sim $
2.5 MW. The microsecond transient performance is affected by the combination of HVPS output filters, output cable length, and load conditions. This article discusses overshoot optimization techniques for megawatt systems, without compromising fast ramp up/down. The optimized solution using damped filter configurations is implemented to verify the improvement at partial load condition of
$\sim $
2.5 MW.