Amplitude Extraction System Of Multiple Frequency Components Based On FPGA

The amplitude extraction of multi frequency components in electrical signal is of great significance for detecting harmonic components in power grid signal,ensuring safe and economic operation of power system;measuring ECG signal in biomedical engineering,reflecting brain nerve activity,studying brain diseases;processing echo signal of radar detection,detecting and identifying detection target,etc.Similar to the harmonic detection of power grid signal in power grid,the signal obtained by Moving Stark Effect(MSE)of Tokamak nuclear fusion experimental device EAST(experimental and advanced superconducting tokamak)is also a mixing signal.The plasma current density can be obtained by measuring the amplitudes of several groups of specific frequency components in the mixing signal.Based on the full investigation of the current situation of multi frequency component amplitude measurement,this paper proposes a multi frequency component amplitude extraction method which can be realized by FPGA,and applies it to the mixing signal processing obtained from MSE(motion Stark effect)diagnosis of Tokamak device,which can not only extract the amplitude of multi frequency component,but also calculate the polarization angle of input light.According to the two key design indexes of MSE diagnosis,the measurement accuracy of polarization angle is better than 5% and the measurement period of polarization angle is less than 10 ms,the design of the system is completed.The main work of this paper is as follows:1)On the basis of understanding the principle of traditional FFT algorithm,aiming at the fact that the traditional FFT algorithm can only obtain the signal spectrum,this paper proposes an amplitude extraction method which can directly obtain the amplitude of multi frequency components,and gives the mathematical derivation and principle analysis.The algorithm can extract the amplitudes of multiple frequency components in the mixing signal at the same time,and further calculate these amplitudes according to the demand.2)A multi frequency component amplitude extraction system based on FPGA is designed.Considering resources and algorithm accuracy,ADC,DAC and FPGA development board are selected,and the external hardware structure of ad-da circuit board is designed.The FPGA logic program of multi frequency component amplitude extraction algorithm is written,and the program is solidified into FPGA development board.3)The principle test,laboratory test and east field test of the system are carried out,and the test results meet the key requirements of MSE diagnosis.