Application of the modified sine-fitting algorithm to directly determine the complex voltage ratio components

This paper analyzes a modified sine-fitting algorithm (SFA) that allows direct determination of the complex voltage ratio (CVR) components. The applied modification consists in using the coefficients obtained by the SFA algorithm for one of the voltages to generate the in-phase and quadrature) components with this voltage. In the second step of the algorithm, the values of the CVR components are obtained by referring the second voltage to the calculated I and Q components. An example of using the proposed modification to determine the components of a self-inductance standard and a capacitance standard is presented. The analysis results were verified by measurements carried out in a digital bridge system with a two-channel digitizer.