Inductor snubber-assisted series resonant ZCS-PFM high frequency inverter link DC-DC converter with voltage multiplier

A variety of high voltage DC power supplies employing the high frequency inverter have difficulty in achieving soft switching considering a quick response and no overshoot response under the wide load conditions which are used in a medical-use X-ray high voltage generator ranging from 20 kV to 150 kV in the output voltage and from 0.5 mA to 1.25 A, respectively. The authors develop a soft switching high voltage DC power supply designed for X-ray power generator applications, which uses lossless inductor snubber-assisted series resonant inverter circuit topology with a multistage voltage multiplier instead of a conventional high voltage diode rectifier connected to the secondary side of a high frequency high voltage transformer with a large turns ratio. A constant on-time dual mode frequency control scheme operating under a principle of zero-current soft switching commutation is described. Introducing the multistage voltage multiplier, the secondary side of turn numbers and stray capacitance of high voltage high frequency transformer is greatly reduced. It is proved that the proposed zero current switching (ZCS) DC-DC high voltage converter topology with dual mode frequency modulation mode control scheme can obtain good transient response and steady-state performance in high voltage X-ray tube load. The effectiveness of this high voltage converter with a high frequency link is evaluated and discussed on the basis of simulation analysis and observed data in experiment.