| As part of research work of BESIII slow control system, this paper introduces the design and test of over-current protection system which protect the Muon front-end electronics readout system.BESIII Muon Counter readout system consists of front-end FEC subsystem and VME subsystem. Over-current protection system is designed for FEC subsystem. The function of over-current protection is to monitor the power supply of FEC data chains and protect it against large current which result from the beam loss of BEPCII.At the beginning, this paper introduces the design background of over-current protection system, including the general and current situation of BESIII and Muon Counter readout system, which illustrates the necessity of the design of over-current protection system. Then the paper emphatically introduces the key part of the design ——the hardware and software design. At last, the test scheme and test result of over-current protection system are given.Base on the design scheme and index of over-current protection system, the hardware design scheme is given in detail. First of all, according to the performance parameters, we selected a high-current load switch TPS2590 which produced by TI Company as the core of the hardware design. The application of TPS2590 achieves the function to monitor the power supply of data chains and provide the status indicator. Secondly, we use the microcontroller which based on ARM kernel to monitor the power switch TPS2590 and communicate with the upper computer. In addition, considering the need of strengthen the anti-jamming capability of over-current protection system, we use the photoelectric coupler in the hardware design.The software design of system includes the program design of lower computer and upper computer. The program of lower computer is introduced emphatically. The lower computer program achieves the function to monitor the power switch and communicate with upper computer. As to update the firmware of microcontroller through traditional method is difficult in the installation of over-current protection system, we adopt the IAP technique in the design of firmware to achieve the function of updating firmware via Ethernet. The function of upper computer program is to communicate with all lower computers.Test of prototype is the last link of the design of system. This part includes the test scheme and test result. The test scheme consists of functional test, performance test, anti-jamming test and stability test. The test result proves that over-current protection system achieve its goal in all aspects. At last, the installation and test of over-current protection system in the spectrometer hall is introduced in detail.The main research results of this paper are as follow:1. Adopt the high-current load switch to achieve the key function of over current protection system at the hardware level, and replace the quick-break fuse of FEC data chains. Compare to the fuse, this method has advantages of fast shut-off and remote program-controlled recovery, in addition, it avoids the delay of interlocking loop result from the safety interlock management using by the slow control system as the original method to achieve over-current protection.2. In consideration of the ground wire interference of Muon front-end electronics, the power of control core and high-current load switch are supplied independently to separate their ground wire, in the meantime, photoelectric couplers are adopted to establish connection. In this way, the anti-jamming capability of over-current protection system is strengthened. |
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