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-freq uency inverters are implemented for constant value control schemes. In part icular, their good transient and steady state performances cannot be achiev ed under wide load variations for a medical-use high-voltage X-ray generato r, ranging from 20kV to 150kV in the output voltage and from 0.5mA to 1250m A, respectively. A high-voltage DC power supply designed for X-ray power ge nerator applications is considered, which uses a series resonant inverter-l inked multistage DC voltage multiplier instead of a conventional high-volta ge diode module rectifier connected to the secondary side of a high-voltage transformer. A constant on-time/variable frequency control scheme of this converter operating at zero-current soft switching mode is described. Intro ducing the capacitor-diode cascaded multistage voltage multiplier, the seco ndary turn numbers and secondary-side stray capacitance of the high-voltage , high-frequency transformer, as well as the rectifier diode voltage rating s, can be greatly reduced. It is shown that the proposed converter control scheme of the two-step selective changed frequency selection switching is m ore effective for improving the output voltage responses. The series resona nt high-frequency transformer-linked voltage-multiplying rectifier is evalu ated for an X-ray high-voltage generator on the basis of simulation analysi s and observed data in experiment.