The boost inverter is a device that is able to generate a sinusoidal voltage with an amplitude larger than the input voltage. Based on the idea of indirectly controlling the output voltage through the inductor current, a dynamical sliding-mode controller for the boost inverter is proposed in this paper. Unlike the usual approach of generating a sinusoidal voltage in both capacitors of the boost inverter, the strategy proposed in this paper focuses on generating a sinusoidal voltage on the load despite the voltage form of both capacitors. A consequence of doing so is that only the desired output voltage is required as reference to implement the controller. Furthermore, it has a fast response, is robust under load and input voltage variations, and yet, is remarkably simple to implement. Although it is strongly nonlinear, it can be implemented using standard electronics circuitry and only needs voltage measurements.

A dynamical sliding-mode control is used to avoid different bit sticking problems present in a conventional vertical oilwell drillstring. The control goal of driving the rotary velocities of drillstring components to a constant positive value is achieved by means of this control. A discontinuous lumped- parameter torsional model of four degrees of freedom is considered. This model allows to describe drill pipes and drill collars behavior. The closed-loop system has two discontinuity surfaces. One of them gives rise to self-excited bit stick-slip oscillations and bit sticking phenomena. The other surface is introduced to accomplish the control goal despite variations in the weight on the bit (key to the dynamics) and other system parameters.

The tracking control problem of amplifying converters encompasses an important practical concern and a challenging theoretical problem. These converters are nonlinear, nonminimum phase systems with saturated control and a highly variable parameter (the load). Such characteristics make amplifying converters devices difficult to control, even for the regulation case. Several aspects of the tracking control problem of the boost converter are addressed. A characterisation of the signal the converter is able to follow is given. The relationship between the parameter values and the tracking error is established, and it is shown that adequate parameters for the DC-to-DC converter are not always suitable for DC-to-AC conversion.