Jean-Yves Gauthier

Nonlinear Technique for Energy Exchange Optimization in Piezoelectric Actuators

Applications of piezoelectric actuators have increased dramatically during the past few decades. However, the capacitive nature of such devices makes their use delicate, especially in terms of power supply, as the instantaneous power may be much greater than the average effective power. This paper places particular focus on the description of a nonlinear technique for piezoelectric actuator control. This technique enables us to significantly increase the energy transfer efficiency of the device by reducing the reactive part of the power. Such an approach has the inverse effect of the well-known synchronized switch damping technique developed to reduce vibrations in smart structures. The proposed solution consists in disconnecting the driving voltage source from the piezoelectric element and switching the system to a passive electrical network at each occurrence of a voltage extremum. This switching strategy is designed to annihilate the reactive energy supplied by the voltage source and to decrease the active energy while ensuring a constant output power. Suppressing the reactive energy is particularly interesting for limiting the dimensions and energy requirements of power supplies. Compared to classical methods, the direct supply of both simulations and experimental validations has demonstrated the effectiveness of the proposed technique for eliminating all of the reactive energy and reducing the active power at frequencies close to the resonant one, while maintaining similar mechanical performances.

Predictive control with efficiency optimization and normalization for a multilevel converter

The good performances of model predictive control for power converters were demonstrated for multi-objective control. A relevant example is the multilevel flying capacitor electronic converter in which both capacitor voltages and output current have to be controlled. Moreover, the efficiency is an essential factor in electrical converter design but few papers focused on it in the control point of view. This paper presents a predictive control scheme for a multilevel converter which minimizes a cost function including a loss related term. The inclusion of a large number of elements into the cost function requires the tuning of many parameters. Normalization of the cost function is introduced in order to help the control designer to choose suitable parameters. Simulation and experimental tests prove that a trade-off between efficiency and accuracy can be achieved by controller adjustment.

Optimal low-stator-frequency avoidance strategy to improve the performances of induction machine sensorless drives

This paper focuses on speed-sensorless drive of induction machine without signal injection. To ensure good performances of the speed observer without the disruptive effects of signal injection, it is possible to avoid the unobservable working points which lead to poor speed observation. To do so, the existing methods aim at avoiding the low stator frequencies. They are nonetheless difficult to use for real applications since they lack flexibility and do not take into account some industrial constraints. The approach presented in this paper consists in formulating all the working constraints in order to build a cost function. By minimizing this cost function, the proposed optimal avoidance strategy is more flexible and can be applied for any industrial application.

A self-synchronizing and low-cost structural health monitoring scheme based on zero crossing detection

Owing to their high specific strength and stiffness, composite materials are increasingly being used in aeronautics and astronautics, but such materials are vulnerable to impact damage and delamination. Structural health monitoring (SHM) techniques have been developed for detecting such defects in recent years. In situ, self-powered and low-cost SHM systems are a developmental tendency of this technique. This paper introduces the principles of a low-cost and self-synchronizing scheme for SHM. Based on the Lamb wave interactions with the structure, the proposed technique relies on detecting zero crossing time instants in order to derive an estimation of the structural state. It is shown that such a method provides a very simple and low-cost way to assess the structural integrity while being computationally efficient. Experimental investigations carried out on a composite plate with an increasing penetration hold validating the proposed technique show its effectiveness for detecting the damage. The proposed approach has also been applied on an aircraft outboard flap to detect the impact damage. The robustness is discussed versus time-shift and magnitude jitter assumptions by using the plate case. The temperature effect is also considered by defining a coefficient array in order to compensate for the material property changes. Finally, an embedded implementation of such a SHM technique is presented by using the proposed damage index.

Electrical parameter observation for induction machine sensorless drive using a sensitivity and observability based EKF

This paper focuses on an effective method for both stator and rotor resistance on-line observation of induction machine driven without mechanical speed sensor. These resistances change over a large range with both the temperature and the flux frequency, making on-line adaptation of these parameters necessary to reach a precise speed observer. To do so, the sensitivity of the speed observation with respect to each resistance and the observability of the resistances are analysed in order to define an observation strategy for the stator and rotor resistances for which the resistances are updated only when necessary. HIL experimentations show that the observation precision on the resistances is good and that the speed observation remains precise and stable despite electrical parameter variation.

Nonlinear semi-passive vibration control based on synchronized switch damping with energy transfer between two modes

Vibration control based on mechanical energy transfer was recently proposed in a technique called synchronized switch damping with energy transfer (SSDET). In this technique, the mechanical energy, which is extracted from a energy source structure is transfered in order to damp another structure. This paper introduces this technique on a multimode vibrating structure. The energy transfer path is from one mode to another. A threshold is set in the control system for the sake of better damping. Experiments are carried out on an one edge clamped plate and both the harmonic response and the impulse response are considered. Results validate the effectiveness of this technique for multimode vibration control.