Modeling the lift DC-DC converter in the state space discrete time

The lift technique has been widely described in the literature by Luo et al. They focus on the steady state operation of the power cells mainly. On the other side, a complete dynamic characterisation is missing up to now. This paper provides the dynamic models of the lift power cells and converters. Capacitive switching characterizes their operation and modeling can be obtained with high accuracy adopting the same procedures that are well suited for describing the dynamic behaviours of other switched capacitor circuits, f.i. the Cockcroft-Walton multipliers. The approach is the state space discrete time protocol with some additional tricks for the precise evaluation of the sampled data values and of the matrices A, B, C and D. The paper describes how to derive the coefficients of the state space matrices of the Luo lift converter and makes reference to a software tool for the automatic analysis. The transfer function matrix of the power cell provides six transfer functions that are plotted versus frequency. After assigning a suitable feedback network, the converter is characterized by four closed loop transfer functions. Forecasts of the frequency responses are compared with experimental results