Frequency Domain Models for Nonlinear Loads with Firing Angle control Devices Part II - Modeling

A frequency domain model for a one thyristor rectifier is developed for the first time in the literature. This model consists in polynomials in terms of the RMS value $V_{1}$ and the initial phase phase $(V_{1})$ corresponding to the voltage fundamental component. A polynomial of this kind gives the RMS value $\mathrm{I}_{2\mathrm{k}-1}$ or the initial phase $\varphi 2\mathrm{k}-1$ of the (2k-1)-th current harmonic for a certain value of the firing angle $\alpha$. This model is built based on measurements of $\mathrm{I}_{2\mathrm{k}-1}$ and $\varphi_{2\mathrm{k}-1}$ on $V_{1}$ and phase $(V_{1})$ for a certain range of firing angles. Two interpolation techniques are used to obtain the above dependences for a new firing angle value. This result is validated by the comparison of the interpolated current waveform with the measured one.