Electronic Current Transducer Design, Built-in Pic Microcontroller And Cpld-based Gis

Electronic current transformer(ECT) is the ideal update of old electromagnetic current transformer and has a series of technical advantages. Thus, it has become a tide to devise ECT.In this paper, the designing of the ECT's sample machine built in GIS is discussed. PIC microcontroller and CPLD are chose to act as the controlling core and modularized design of the ECT's primal side and secondary one is processed according to ECT's international standard- 《IEC60044-8》 and overseas related products' successful design. In addition, the design methods of low power consumption and embedded system are fully applied. The sample machine transmits test channel and protection one simultaneously and reaches high precision of test level 0.2, which implements ECT's theoretic advantages in engineering.In this paper, the merging acquisition unit at three-phase ECT's primal side is divided into several independent modules, namely sensor, data acquisition board and merging communication board, whose hardware and software are devised separately. In the part of sensor, several schemes are compared in performance and then the final choice is made. In the part of data acquisition board, the related chips are chose according to the board's required function. Then the software flow chart is showed. In the part of communication board, its hardware and software are configured according to digital system's top-to-down design method. Simultaneously, the communication agreement between the board and data acquisition board as well as the three-phase data frames' code scheme is made. As to signal distribution unit at the secondary side, the signal reverting circuit which deals with single-phase data frames' code scheme and the industrial Ethernet circuit structure are discussed.In this paper, the full simulation of some major modules is processed in Proteus simulation software and Quartus II 5.0. In the end, the sample machine's single-phase test level precision is tested. The simulation and test result show that the sample machine fulfills expected technical targets and that the design in the paper is successful and of high quality.