Series resonant ZCS-PFM DC-DC converter with multistage rectified voltage multiplier and dual-mode PFM control scheme for medical-use high-voltage X-ray power generator

In general, high-voltage DC power supplies employing a variety of high-frequency inverters are implemented for constant value control schemes. In particular, their good transient and steady state performances cannot be achicved under wide load variations for a medical-use high-voltagc Xray generator, ranging from 201cV to 1501V in the output voltage aiid from 0.5mA to 1250niA, respectively. A high-voltage DC power supply designed for X-ray power generator applications is considered, which uses a series rcsonaiit inverter-linked tnultistage DC voltage multiplier instead of a conventional high-voltage diode module rectifier connectcd to the secondary side or a high-voltage transformer. A conslant on-tinieivariable frequency control scheme or this converter operating at zero-current soft switching mode is described. Introducing the capacitor-diode cascaded multistage voltage multiplier, the secondary turii numbers and secondary-side stray capacitance of the highvoltage, high-frequency transformer, as well as the rectifier diode voltage ratings, can be grcatly reduccd. It is shown that the proposed converter control scheme of the two-step selective changed frequency selection switching is more effective for improving the output voltage responses. The series resonant high-frequency transformer-linked voltage-multiplying rectificr is evaluated for an X-ray high-voltage gcnerator on the basis of sirnulalion analysis and obscrvcd data in experiment.