Study On ICT-Type High-Voltage Power Supply Based On Dummy Primary Winding Compensation

Insulated core transformer(ICT)type high-voltage power supplies(HVPSs)have many advantages such as compact structure,low cost,high stability,high reliability and high energy conversion efficiency,thus offering unique advantages in low and medium energy region irradiation accelerators.However,the segmented structure of the core limb results in lots of leakage flux in the ICT,which leads to inconsistent flux density in the core segments and non-uniformity output voltages on disks.This reduces the performance of the HVPSs and voltage compensation is a major difficulty in its design and engineering implementation.Recently,the rapid development of low-and medium-energy irradiation accelerators requires ICT-type HVPSs to further improve their performance and achieve high-voltage and high-power output,which puts forward higher demands on voltage compensation.Combined with the HUST-ICT HVPS prototype,this paper expounds the working principle and main structure of the ICT-type HVPS.The basic equations of the HVPS were established to analyze its operating characteristics.Based on the field-circuit coupling finite element method,the prototype was modeled and simulated,and experiments were carried out.Experiments show that the disk voltage,the load regulation rate,and the energy conversion efficiency under different load conditions are in good agreement with the simulation results,which fully verifies the effectiveness of the modeling and simulation methods.It lays a foundation for in-depth research on the key technologies of ICT-type HVPSs.To realize high-voltage and high-power ICT-type HVPSs and further optimize its main performance indices,a theoretical study of ICT with dummy primary winding(DICT)HVPS was carried out.This paper expounds the basic structure and working principle of the voltage compensation method based on dummy primary windings.And the voltage compensation characteristics of the method with dummy primary windings were analyzed by establishing an equivalent circuit model.Combined with magnetic circuit model and finite element simulation,the operating characteristics of DICT HVPS were studied.Compared with the conventional ICT,the non-uniformity of disks’ voltage and the load regulation rate are significantly improved.On the basis of DICT,a novel ICT with double dummy primary windings is further proposed and designed.The electromagnetic design of DICT is the kernel of the physical design of the DICT HVPS.In this paper,a complete electromagnetic design method is proposed in combination with the design of an 800 k V/50 m A DICT HVPS.Based on the principle of minimum power loss,the core radius and working magnetic flux density are determined,and all the initial design parameters of DICT are obtained.On this basis,a comparative analysis of two ICT structures with dummy primary windings was carried out to ascertain their ranges of application.The adjustment of existing DICT compensation parameters depends largely on engineering experience of the designers,which is inefficient and difficult to obtain optimal parameters.To solve this problem,a fast optimization method for compensation parameters of DICT HVPS based on a modified particle swarm optimization(PSO)algorithm is proposed in this paper.Firstly,a mathematical model for optimising the compensation parameters and a circuit simulation model were developed.Secondly,the standard PSO algorithm was modified in four aspects.Finally,the modified PSO algorithm was used to optimize the compensation parameters of the 800 kV/50 mA DICT HVPS which greatly improved the design efficiency and further improved the main performance indices.Moreover,the method allows the specification of the number of secondary winding turns,thereby reducing costs and technical requirements.