Hybrid dynamical model for reluctance actuators including saturation, hysteresis and eddy currents

A novel hybrid dynamical model for singlecoil, short-stroke reluctance actuators is presented in this paper. The model, which is partially based on the principles of magnetic equivalent circuits, includes the magnetic phenomena of hysteresis and saturation by means of the generalized Preisach model. In addition, the eddy currents induced in the iron core are also considered, and the flux fringing effect in the air is incorporated by using results from finite element simulations. An explicit solution of the dynamics without need of inverting the Preisach model is derived, and the hybrid automaton that results from combining the electromagnetic and motion equations is presented and discussed. Finally, an identification method to determine the model parameters is proposed and experimentally illustrated on a real actuator. The results are presented and the advantages of our modeling method are emphasized

A distributed maximum power point tracking system for solar electric vehicles

\u3cp\u3eCurrent Solar Electric Vehicles have flat roofs, in an attempt to reduce irradiance mismatches within the strings of PV cells. As a result the aerodynamic performance and design freedom of such vehicles are limited. This paper presents a distributed maximum power point tracking methodology specifically aimed at Solar Electric Vehicles to overcome this problem. As a starting point, the PV-To-isolated bus architecture is selected, since it processes a low amount of power and easily extends to an arbitrary number of groups per string. A new control strategy for this architecture is introduced, that allows for local, decoupled, true maximum power point tracking. The architecture requires isolated, bidirectional, load independent converters, which were realized by means of a series connected synchronous boost converter and LLC resonant converter.\u3c/p\u3

Disturbance observer-based control of a dual output LLC converter for solid state lighting applications

Feedback sensor isolation is often an expensive necessity in power converters, for reasons of safety and electromagnetic compatibility. A disturbance observer-based control strategy for a dual-output resonant converter is proposed to overcome this problem. Current control of two LED loads is achieved through estimation rather than measurement. Robustness against temperature changes, which have significant impact on the behaviour of the LEDs, is achieved through estimation of offsets in the forward voltages of the LED-strings. The power converter and LEDs are modelled accurately to obtain a good estimation accuracy. The whole implementation is steered towards a low cost solution

Sensing movable receiving coils by detection of AC current changes on the primary side of a multi-coil system

Position detection is very important for inductive power transfer systems with movable receivers, in order to switch off inactive coils and to reach a high efficiency. The solution presented in this paper is based on the measurement of the current amplitudes in sending coils, which show a significant difference between no targets, metallic targets and receiving coils. A galvanically separated circuit is designed to implement the new method by transforming the current of the sending coils to a DC voltage and then comparing it to the detection threshold. Finite element simulations were carried out to predict the value of the detection threshold. Both simulation and experimental results show that the circuit fulfils the detection requirements with high precision and high detection height. The proposed method represents a smart, efficient and low cost detection technique for inductive systems with a movable receiver, independently on position and speed

Contactless energy transfer through air by means of ultrasound

An alternative approach to the wireless transfer of energy is proposed, employing acoustic waves in air. Unlike conventional methods, acoustic energy transfer is able to achieve energy transfer at high efficiencies over distances that are large in comparison to the dimensions of the transmitter and the receiver. This paper gives an overview of the principle and explains the different loss mechanisms that come into play. A theoretically limit on the achievable efficiency is calculated. It exceeds that of a comparable inductively coupled system by an order of magnitude. First preliminary measurements indicate that AET is feasible, although the measured efficiency is lower than the predicted theoretical limit

Improved current estimation in paralleled half-bridge converters

When paralleling half bridges, their individual currents should be balanced to prevent large circulating currents. This paper improves an existing perturbation-based current estimation method by modifying the perturbation signal allowing a faster estimation of the currents, resulting in a reduction of current stress on components

Adaptive isogeometric analysis applied to an electromagnetic actuator

In this paper, a magnetostatic solver for linear and nonlinear soft-magnetic material characteristics, a time-harmonic eddy current solver, and the corresponding function-based error estimates are implemented in an established adaptive isogeometric analysis framework. The simplified truncated hierarchical B-spline basis functions are investigated on the multipatch geometry of a magnetic circuit, as they offer several beneficial properties, including a drastic reduction of the number of degrees of freedom compared to the references under uniform refinement. Global error estimate and global parameters convergence are illustrated for different refinement strategies and polynomial orders. Finally, the computational effort is analyzed

Grid-connected converters with voltage support using only local measurements

This paper considers a single-phase grid-connected converter in the presence of non-linear loads. A local voltage support strategy is proposed to compensate the harmonics caused by the loads. This is an added feature implemented in parallel with a conventional current control method, and distinctively, it does not need measurements of the grid or load current. The converter output current consists of two components: a part at the fundamental frequency for power injection, and a part to compensate the harmonics introduced by the non-linear loads. As a result, the grid current harmonic distortion is minimized and the local voltage quality is enhanced. Simulation and experiments validate the effectiveness of the proposed voltage support strategy