Detailed Derivation and Minimization of the Equivalent Parasitic Capacitances of a High-Voltage Multiplier Based on the Complete Model.

The authors' previous paper presents the complete model of parasitic capacitances in a high-voltage (HV) multiplier in the HV generator in a medical X-ray machine. The equivalent parasitic capacitance of the multiplier Cem based on the model is exhibited to interpret the role of the parasitic capacitances in circuit operation of the generator. Without derivation of the analytical expression of Cem, its dependence on the component parameters is directly shown, which leads to guidelines for minimization of Cem. However, the complete capacitance model has a complicated structure and contains voltage-dependent capacitances and voltage sources, which gives complexity to derivation of Cem as well as difficulties to clear understanding of the voltage dependence of Cem. Thus, this paper presents the detailed derivation and analytical expression of Cem. Exactly speaking, the key part of Cem, namely, the total chain capacitance CDcht that determines the voltage dependence of Cem, is conducted. A simple way is presented for the derivation of CDcht. The derivation enables a clear understanding of the voltage dependence of CDcht. Moreover, a design procedure for minimization of Cem is created, accompanied by a case study. It gives designers step-by-step rules to make an optimal HV multiplier with a minimum Cem. [ABSTRACT FROM AUTHOR]