High-Order Switching Surface in Boundary Control of Inverters

A high-order switching surface for boundary control of inverters is presented in this paper. The concept is based on using the natural response of the power stage to formulate a logarithmic function to approximate the ideal switching surface. With the proposed control method, the inverter exhibits better dynamic responses than the ones with the first-order or recently proposed second-order switching surfaces. It will also be shown that the first- order and second-order switching surfaces are the low-order approximations of high-order switching surface. As the high-order switching surface is close to the ideal switching surface, its high trajectory velocity along the switching surface makes the inverter state trajectory move toward the steady-state operating point in two switching actions under large-signal disturbances. The effects of the parametric variations on the output voltage and the large- signal characteristics of the inverter will be discussed. The proposed control method has been successfully applied to a 300-W, 110-V, 60-Hz, single-phase full-bridge inverter. The steady-state and large-signal dynamic behaviors of the inverter supplying to resistive, nonlinear inductive, and full-wave rectifier loads will be given.