Comparison of latch-based and switch-based, sampled-data, three-phase, PWM, voltage-source inverter models for dynamic analysis

Abstract

A switch-based, sampled-data, three-phase, pulse width modulated (PWM), voltage-source inverter (VSI) model for dynamic analysis has been derived and compared with the existing latch-based model. Comparisons were made for both time-domain, large-signal and z-domain, small-signal analyses. The switch-based model has the advantage of including inverter switching ripple current in the time-domain, large signal analysis, with minimal computational effort. The z-domain, small-signal model is made time-invariant using an approximation, with the limitations of using this approximation discussed. The switch-based z-domain model shows no significant difference from the latch-based model. This result confirms the validity of the latch-based analysis for z-domain for controller tuning, as long as the approximation needed for time-invariance is valid.