Active damping of a 6th order 3LC output filter with state-feedback

Standard solution to reduce switching ripple in power converters is to employ LC(L) output filters, with higher attenuation requiring higher switching frequency and/or larger filter size. High switching frequency can increase the converter losses, whereas large filter reduces the bandwidth and increases cost of the power converter. The alternative path of increasing the filter order is taken in this paper. To be more exact, a 6th order filter consisting of 3 series connected LC blocks is employed to achieve very high ripple attenuation and increased converter bandwidth without increasing the switching frequency. In contrast to previously proposed high-order filter solutions active damping is employed yielding no penalty to the converter efficiency. The active damping is achieved via state-feedback control, i.e., Linear Quadratic Regulator, with the state information reconstructed only from capacitor voltage measurements with a Luenberger observer. The complete design is evaluated in simulations and validated on the experimental synchronous buck converter achieving in excess of −80 db ripple attenuation in one decade

Finite-step terminal ingredients for stabilizing model predictive control

This paper proposes a novel construction of the terminal cost and terminal set in stabilizing model predictive control that uses finite-step Lyapunov functions and finite-step invariant sets. This construction results in a periodic terminal set constraint associated with a finite sequence of terminal sets, out of which none is required to be invariant. We argue that constructing such sets is easier and more scalable compared to invariant sets, while a comparable region of attraction is obtained for the same prediction horizon. In the one step case the proposed stability conditions reduce naturally to the standard terminal cost and constraint set stability conditions

Design and Control of an Omni-Directional Mobile Robot

This paper introduces an omni-directional mobile robot for educational purposes. The robot has full omni-directional motion capabilities, thanks to its special Mecanum wheels. The paper provides some information about conventional and special wheels designs, mechanical design aspects of the Mecanum wheel and also electronics and control strategies: remote control, line follow, autonomous strategy

Stabilization of bilinear power converters by affine state-feedback under input and state constraints

This brief presents a novel systematic procedure for the synthesis of affine state-feedback control laws for power converters. The proposed synthesis method is applicable to power converters with a bilinear averaged model and comes with a guarantee of closed-loop stability under hard state and input constraints. The low complexity of the resulting control law translates into a reduced cost of the control hardware, while nonconservative constraint handling yields a higher reliability of the power converter. Moreover, the incorporation of state constraints in controller synthesis can be exploited to achieve a higher power density for the converter. The effectiveness of the proposed controller synthesis method is illustrated on a buck-boost converter case study. Both simulation and real-time experimental results are reported

Active damping of power converters with modular basic crossover correction cells

High-precision applications typically demand very-low ripple, fast response, and high efficiency. The newly proposed concept of Basic Crossover Correction Cell (B3C) aims to achieve exactly that by processing the current ripple independently from the main bulk current. As a consequence, correction cells can be constructed from lower-power switching devices with reduced stress, as compared to conventional multi-level and cascaded converters. However, to separate the ripple current from bulk, shunt inductors and DC current blocking capacitors are employed, and give rise to more complicated converter dynamics. The internal converter dynamics leads to unwanted oscillations at the output during transitory operation, and thus needs to be actively controlled to achieve fast dynamic response. The focus in this paper is on control relevant modeling of the converter and compensation of the unwanted dynamics. A revised modulation scheme is proposed for the B3C, which allows direct control of internal resonances. Two control methods employing it are discussed, i.e., distributed virtual resistance damping and observer-based state feedback. Control strategies are evaluated in simulation and compared to more conventional alternatives as state-feedback with the original modulation scheme and passive damping