NSRRC Activity Report 2023

Facility Development and Status 095 The QMPS units have an internal topology similar to that of the BMPS but with a single full-bridge architecture and utilize a 40 kHz PWM modulation signal to modulate the output current. The capacity specification for the QMPS is 150 A/± 425 V. 1 Installation and Cabling All the installation requirements were satisfied during the installation of the BACMPS for the TPS booster ring. These requirements included provisions for cooling water, controller settings, cable specifications, and specifications for auxiliary interlock configurations. Careful cable routing strategies, particularly those involving crossover loops, were employed to minimize interference caused by the magnetic fields generated by the output current. This technique effectively reduced magnetic interference in the TPS area, ensuring compliance with high-energy output requirements and addressing challenges associated with high-current operations. A dedicated soundproof chamber was established to mitigate low-frequency noise generated during BMPS operation. These measures successfully reduced the low-frequency switching noise from 84 to 54 dB. Commissioning Issues of BACMPS Despite successful laboratory tests under purely resistive loads, the performance of the BACMPS during the initial TPS commissioning in 2014 did not meet expectations. The main challenges encountered were twofold. First, the effects of parasitic capacitance on the magnet load side resulted in the BACMPS generating common-mode high-frequency 1 kHz noise during AC mode operation. This noise led to poor current reproducibility at the injection point. Second, the distinct characteristics of the BMPS and QMPS output currents, including variations in phase delay angles and the lack of synchronous timing control in the FPGA controller, made it challenging to achieve synchronized waveforms for the BACMPS. Effects of Parasitic Capacitance in the Booster Ring Bending Magnet The effects of parasitic capacitance in the bending magnets of the booster ring, specifically between the SkiiP IGBT modules M1 and M4 (where the BMPS output terminals are considered a floating ground reference), pose unique challenges. Because the support girder of the bending magnet is grounded, the wire turns of the bending magnets and the girder form a capacitor, and 60 units of bending magnet in series create parasitic capacitance. Figure 2 Fig. 2 : Parasitic capacitance with the ground current path of the booster ring dipole magnet.