A 100 kW high voltage power supply for dual energy computer tomography applications

Dual energy X-ray computer tomography (CT) offers enhanced imaging and reduced radiation dose. A conventional technique is using two tubes, each energized by its high voltage power supply (HVPS) at different voltage levels. This approach is straightforward but costly. An alternative is using a single tube fed by an HVPS capable of generating these same voltages with fast transitions from one state to another. A conventional HVPS with exceptionally fast dynamics is less costly than a modulator employing a set of HV switches. Such an HVPS is described in this paper. Key technology includes an all-solid-state modular IGBT-based HV converter with energy-dosing inverters operating at up to 70 kHz. The inverters' output voltages are phase-shifted, which yields low ripple and fast risetime combined with low stored energy. Controls provide standard operating features and means of communicating with the outside world. Digital processing enables predictive control for generating clean transitions from one state to another in a wide range of load/line conditions. The HVPS incorporates also two filament power supplies and a high-speed starter. Results of extensive testing with both resistive loads and X-ray tubes are presented. The developed techniques can also be used in other applications requiring low-cost generation of high-power HV pulses submillisecond- to many seconds-long.