Position estimation at low/zero speed for permanent magnet synchronous machines is commonly achieved with the injection of high-frequency signals. This article presents a new sensorless scheme that accurately observe the rotor angle at low speeds, including standstill condition, without injecting high-frequency signals. The algorithm is built upon a previous sliding-mode current controller and uses the switching functions slopes inaccuracies produced by the saliency effect to determine the rotor position and speed. Thanks to the equivalent control concept and together with a sliding-mode-based phase-locked loop observer defined by a complex switching function, the algorithm provides both rotor position and speed in a compact form. This article includes the main working principle and defines the operational range of the proposed scheme. Finally, the feasibility of the method is corroborated through experimental results in sensorless configuration.

A new controller for a grid connected inverter with an LCL filter is proposed in this paper. The system is described by its complex representation and the controller is designed using the complex root locus method. The complex representation allows a considerable reduction in the order of the system, simplifying the design task and making it possible to use of advanced techniques such as the complex root locus. The new complex controller adds an extra degree of freedom that makes it possible to move the poles of the systems, and improve stability and speed of response compared to the conventional controls. The paper include a detailed discussion of the effect of the gains of the controller on the root locus. The proposal is validated with simulation and experimental results.

This work presents a nonlinear control strategy for a magnetically coupled multiport dc-dc converter aimed at automotive applications. First, a behavioural dynamic model, based on averaging the power flowing among the ports, is derived. Then, a control algorithm, based on feedback linearization techniques, is proposed. Essentially, the controller ensures decoupling and a linear dynamic behaviour thanks to a transformation of control and state variables, and a conventional PI action is devised to render asymptotic stability, as well as robustness to load uncertainties. The inversion of the control transformation, which involves nonlinear terms, is carried out using linear approximations with no significant performance decay. Hence, simplicity and efficiency are the main features of the control design. The proposed controller is validated via experimental results.

In this brief two sliding mode control alternatives to regulate the stator voltage amplitude for a stand alone wound rotor synchronous generator are presented. Both controllers use the stator voltage -component error in the sliding surface. In a first case an outer proportional-integral (PI) loop controller is added to provide the proper d-voltage component reference. The second approach consists in extending the dynamic system to include the integral term as state variable and to modify the former sliding surface by adding this new state. Finally, both simulations and experimental results validates the proposed algorithms.