Alternating Integrator Design Based On FPGA

The discharge time of the new generation tokamak gets to a thousand seconds. Integrator is one of the key devices of its electromagnetic diagnosis system. In order to ensure the accuracy of electromagnetic diagnosis, we need to design a integrator which can work for a long time and has the characteristics of high precision, real-time control, low drift and good electromagnetic compatibility.This paper investigates the research status of the integrator domestic and aboard, and analyzes the working principle, the realizing forms and the existing problems in detail, designs the alternating integrator based on the field programmable gate array (FPGA). The alternating integrator is adopted FPGA as the core processor unit, two-way real-time compensation integral unit to integrate the differential signal alternately, then the analog signal of the two integral units is converted to digital signal by the analog to digital converter (ADC). The two integral signal is spliced by FPGA. The effective signal is converted to analog signal by the digital to analog converter (DAC), then the analog signal outputs through the isolation circuit. In addition, the system uses Verilog HDL language as the program design language, and verifies the correctness of the design scheme by the DSP Builder. The circuit board layout ensures the electromagnetic compatibility.In the spring of 2014, the discharge test of the EAST showed that the alternating integrator spliced the two integral signal very well with good stability and strong anti electromagnetic interference ability, satisfied the designing requirements of the tokamak.