Nonlinear current observer for backstepping control of buck-type converters

Two backstepping control schemes are developed for buck-type converters for two different types of loads. The first considers an unknown passive load, while the second considers a time-varying current source load. Both schemes utilize a novel inductor current observer which eliminates the need for a costly current sensor. For the passive load, the output voltage tracking objective is met using only parameter knowledge and the output voltage measurement. For a current source load, the output voltage tracking objective is met using parameter knowledge and measurement of output voltage and load current. A stability analysis and simulation results validate each approach.