A Direct Converter for High-Energy Physics Applications

This paper describes the development of a high-frequency resonant-power converter for high-energy physics (CW) applications. The proposed converter topology has been demonstrated by the construction of a laboratory demonstrator that produces 25 kV with less than 1% ripple at 1 A (25 kW). The converter is a direct converter topology operating without the use of a dc link, significantly reducing the size and weight of the converter and resulting in a relatively high-energy density converter. A high-frequency (20 kHz) resonant circuit is employed which provides inherent short-circuit protection of the converter from the output, while reducing the turns ratio of the transformer. The transformer is integrated into the resonant circuit and operates at the same frequency as the resonant circuit (20 kHz). To achieve high-frequency and high-flux operation of the transformer, an amorphous (nanocrystalline) core is used, further reducing the physical size of the converter. Use of the resonant circuit also allows for soft switching of the IGBTs. High-frequency operation allows for a reduction in size of both the transformer and output filters, thereby removing the need for operation with a crowbar. All of the techniques implemented in the prototype converter may be extended to higher voltage higher power systems.