Some active vibration control methods are based on mathematical models. In these cases, parameter variations play an important role in the system performance. As it is not possible to know in advance the precise values for all parameters of the mechanical system, a possible alternative is to design robust controllers that take into account the uncertainties. In this context, this work presents a vibration active control technique devoted to rotating machinery by incorporating electromagnetic actuators, which considers uncertainties in the parameters of the system. the gains of the electromagnetic actuator are determined by using linear matrix inequalities, which consist in a powerful tool for the cases in which parameter uncertainties are taken into account. In addition, Kalman estimators are employed to deduce the modal states of the system. The model of the rotating system is obtained by using the finite element method and the potentiality of the methodology for applications in engineering was investigated through experimental tests.

A Lossless commutated Boost Converter applied as an active PFC stage for Uninterruptible Power Supply (UPS) systems is presented in this paper. In this new PFC topology, as the stored commutation energy is delivered to the battery set, a suitable design can be made to avoid the use of a battery charger, therefore, eliminating an additional power stage commonly found in ordinary boost converter structures applied as an active PFC stage for UPS. Thus, one can conclude that a suitable design can provide autonomous UPS systems.Detailed experimental results are presented corroborating with simulations analysis also included in this work. The proposed structure presents good performance, becoming a good candidate for PFC stage of on-line UPS structures.Mathematical analysis and a complete description of the proposed topology operation are also presented.

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