Performance Test Results of Magnet Power Supply

A high stable magnet power supply (MPS) was developed, which was a bipolar type with 200 A of the output current at the 36 V of output voltage. The MPS has been implemented by the digital signal processing technology using the DSP, FPGA, ADCs and so on. The output current stability of the MPS showed about 6 ppm peak-to-peak in a short term experiment at its full 200 A output current. The long term stability was shown in 15 ppm peak-to-peak for 10 hours at 200 A. And the others experimental results about the MPS were shown in this paper. INTRODUCTION The particle accelerator needs a highly stable magnet power supply (MPS) to assure the stable beam dynamics. A MPS must provide high-stability output current, fast response, high reliability, etc. It should also be easy to maintain. The stability and accuracy of the MPS are very important specifications because they directly affect the beam dynamics of the accelerator operation. Nowadays the MPS is developed by switching mode type using FET or IGBT devices that are controlled by a digital signal processor (DSP). This design is efficient, small, lightweight, and has good dynamic response but switchingmode MPS generates electrical noises whenever switching devices are turning on or turning off because of their generally high switching voltage and current. The shortterm stability of the MPS is affected by the several causes which come from the control loop responses, surrounding switching noise, analog signal processing including ADC circuits, and so on [1]. Ripple components of the input rectifier are also one of the sources which make MPS stability worse [2]. The one of the cause of the long-term stability of the MPS comes from the temperature drift of components in MPS. Improper ground configurations can provide the path on which noise can propagate from its source point to all over the system. These components are very small but can degrade the performances of an analogto-digital converter (ADC) circuits with the fine voltage fluctuation. This paper describes the design schemes of the MPS. The results of the various experiments such as short term stability, long term stability, repeatability and step responses were showed. SYSTEM CONFIGURATION The developed MPS was divided into three parts as shown in the Fig. 1. The first is a rectifier to make DC link voltage. The second is the two power stacks which has the current driving capacity of 100 A, respectively. Thus two power stacks are operated in parallel to increase the current driving capability. The last is digital controller configured with DSP TMS320F28335 from TI [3]. Three Phase Δ-Y Rectifier Power Stack #1