Abstract
For most high‐precision power analyzers, the measurement accuracy may be affected due to the nonlinear relationship between the input and output signal. Therefore, calibration before measurement is important to ensure accuracy. However, the traditional calibration methods usually have complicated structures, cumbersome calibration process, and difficult selection of calibration points, which is not suitable for situations with many measurement points. To solve these issues, a nonlinear calibration method based on sinusoidal excitation and DFT transformation is proposed in this paper. By obtaining the effective value data of the current sinusoidal excitation from the calibration source, the accurate calibration process can be done, and the calibration efficiency can be improved effectively. Firstly, through Fourier transform, the phase value at the initial moment of the fundamental frequency is calculated. Then, the mapping relationship between the sampling value and the theoretical calculation value is established according to the obtained theoretical discrete expression, and a cubic spline interpolation method is used to further reduce the calibration error. Simulations and experiments show that the calibration method presented in this paper achieves high calibration accuracy, and the results are compensation value after calibration with a deviation of ±3 × 10−4.
Highlights
The calibration of a high-precision power analyzer is a key function in the signal measurement process
The simulated waveform of the original sequence of xk is shown in Figure 3, the abscissa represents time, and the ordinate represents amplitude: Using the method mentioned above, the mapping relationship between the sampling value xk and the theoretical value yk is established through the theoretical discrete expression, and the 32 sampling points obtained are calibrated, as shown in Figure 4: Use cubic spline interpolation to make a continuous smooth calibration curve SðxÞ from 32 calibration points
The comparison of experimental results verifies that the calibration method proposed in this paper is effective in the application of nonlinear systems and has high calibration accuracy
Summary
The calibration of a high-precision power analyzer is a key function in the signal measurement process. Kong [13], and others classified the errors of the acoustic vector sensor array and designed an optimization model and error selfcalibration algorithm for the acoustic vector sensor array This algorithm can perform quite well in parameter estimation, but when the mathematical model is established, the iterative calculation of coefficients still needs much work. This method is generally not used in actual projects which require a large number of data calculation [14]. A calibration algorithm based on discrete Fourier transform (DFT) is provided in paper [17, 18] This method directly carries on the Fourier transform processing to the sampled data sequence, which has the advantages of fast operation speed and less computation. By interpolating the data, an ideal calibration curve is obtained
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