The Application Of Resonant Converter And Digital Control Technology In Accelerator

Many kinds of power supplies are applied in particle accelerators. Most of them use the analog PWM-control mode combined with chopper converter structure. Good performance in stability, dynamic properties and maintainability are required in power supplies for accelerators. With the development of technology, the analog control circuits used in PWM power supplies are gradually replaced by digital control circuits which play an important role and have been used in many domestic and foreign accelerators.Resonant power supply technology has been developed rapidly in current days. The advantages and characteristics of this technology are very suitable for the small and medium power supplies in accelerator. In this work, resonant power converters and the high-resolution FM digital control technology are attempted to introduce into the accelerator power supplies. In the mean time, several important resonant power supply topologies are studied and analyzed the application possibility of the resonant power supply in accelerator.High-resolution FM control circuits and simplified peripheral circuits are required in digital resonant power supplies. Making reasonable selection of many controller chips in the market, DSP chip TMS320F28335made by Ti Company was chosen as the core processing chip for the digital power supply controller. According to the strict requirement of the power supply on stability, an18-bit analog-digital chip AD7690was chosen for data acquisition. Additionally, to improve the performance of the data acquisition circuit, a temperature management circuit was designed. And a local/remote human-interface circuit was designed to facilitate communication. A set of FM DSP digital controller card and high resolution AD card were developed for resonant power supply. Lots of hard work was spent on improving the FM resolution for resonant power supply modulation. A kind of DDS chip AD9851stepped at1Hz resolution was used in resonant power supply modulation. Some experiment results have been achieved.In practical application, the resonant converter technology and high precision FM digital control circuit is applied to high voltage of electron gun power supply and klystron focusing current stabilized power supply. This work achieves the design effect and illustrates the feasibility of the technology applied to accelerator power supply. In this work, the parallel-resonant topology converter was adopted in50kV/5mA electronic gun high voltage power supply and serial-resonant topology converter was adopted in35A/35V klystron focusing current power supply.The working principle and voltage-current control characteristic of four important resonant power supply of SRC, PRC, LCC and LLC under the condition of without filtering inductance were studied. Analyzed their sine steady-state characteristics and established their fundamental equivalent circuits. Two methods were used in building the resonant power supply model. Firstly, linearization approximate the frequency-voltage control curve near the nominal working frequency point, finding the relationship between the modulated period of the Switching signal and the output voltage of the power supply. The model built by this method can be validated by software simulation. Secondly, use the extension description function method to extract the fundamental component of the resonance signal as the basis of analyzing the resonant power supply. Small signal model and transfer function of the resonant power supply were obtained by adding a small signal disturbance to the steady state resonant parameters. This work can provide a design reference for the power supply compensator.Through the work of this paper we can verify that the digital control technology of the resonant power supply can be applied to the accelerator power supply. At present, this technology is mainly suitable for small and medium-sized power supply, but with the progress of digital resonance technology, the superposition of the light resonant power supply module will push the resonance power technology development towards the direction of the high-power supply.