Adaptive Sliding Mode Control of Three-Phase Two-Level Converters

In previous chapters, the parameters of the converter model are assumed to be certain. However in real applications, the converter model is often obtained based on several assumptions, such as that the characteristic of electronic devices does not vary with time. As can be seen, the model obtained in this way is not accurate, and under some conditions its behaviors may have big difference with real system. Therefore, the designed controller needs to be robust against the parameter uncertainty of the mode. Based on this reason, the parameter uncertainty must be taken into account, which may be caused by the filtering inductor L and its series resistance r, grid voltage frequency ω, which can be represented as follow: 10.1L=L0+ΔL,r=r0+Δr,ω=ω0+Δω, where L₀, r₀ and ω₀ are nominal values, ΔL, Δr and Δω are parameter deviation, which can be assumed to be slow-varying signals.