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When a power-electronic converter is introduced into a linear network, voltage and current harmonics of differing orders become coupled (through the modulation effect of the converter). The interharmonic coupling introduced by the modulation effect of a converter may be mathematically represented through a frequency coupling matrix (FCM). Given that the source of the coupling is a modulation process, researchers have, in the past, focused on deriving the FCM in the frequency domain-a process that requires the truncation of the harmonic representation of signals. This paper presents an alternate approach to evaluate the FCM based on a time-domain derivation. In contrast to frequency-domain-based methods, it is shown that the time-domain approach avoids truncation. Furthermore, the time-domain approach does not require system linearization about an operating point; thus, the FCM is not limited by small-signal assumptions. [ABSTRACT FROM AUTHOR]

An iterative method based on a hybrid time/frequency-domain approach is proposed in this paper to solve for the steady state of a pulse width modulated voltage-source converter (VSC) with a dq-frame closed-loop controller. The method solves the linear controller equations in the frequency domain, while solving the VSC equations using time domain techniques. The model is validated against time domain simulation results. It is shown that the hybrid time/frequency-domain approach is both highly efficient and accurate, and it provides a viable alterative to brute-force time domain simulation for large signal harmonic analysis of the VSC. [ABSTRACT FROM AUTHOR]