An Experimental Analysis of Frequency Characteristics in LLC Resonant Converter with Cockcroft-Walton Circuit

High step-up DC-DC converters with the Cockcroft-Walton (CW) circuit are used for high DC voltage power supplies such as an electron beam irradiation device, a particle accelerator, and an insulation test device. As these devices are large and heavy, reducing the size is required. High frequency operation generally reduces the value of passive devices: an inductor and a capacitor. However, the switching loss increases at high frequency operation. Therefore, an LLC resonant converter has attracted attention because it maintains Zero Voltage Switching (ZVS) for high efficiency. This report proposes an LLC resonant converter with the CW circuit as the rectifier. In addition, the additional inductor in the CW circuit occurs the LC resonance for increasing the output voltage. As a result, the proposed DC-DC converter achieves both ZVS and high step-up. This report experimentally clarifies the verification of the proposed DC-DC converter.