Synchronized Switch Damping Research Articles

Damping Behavior of Semi-passive Vibration Control using Shunted Piezoelectric Materials

Piezoelectric transducers in conjunction with appropriate electric networks can be used as mechanical energy dissipation devices. Semi-passive vibration control devices using nonlinear methods have experienced significant development in recent years, due to their performance and advantages compared with passive and active techniques. More precisely, synchronized switch damping (SSD) and derived techniques, which have been developed in the field of piezoelectric damping, lead to a very good trade-off between simplicity, required power supply, and performance. This technique consists of nonlinear processing of the piezoelement voltage which induces an increase in electromechanical energy conversion. The control law consists of triggering the inverting switch on each extremum of voltage (or displacement). The purpose of this study is the experimental observation of piezoelement damping sensitivity to variations of amplitude and frequency of excitation force. In addition, the effect of the size of piezoelement area on the vibration damping in high and low values of these parameters has been studied using SSDI method. The proposed method for switching sequence is based on statistical evaluation of the structural deflection.

Piezoelectric vibration control by synchronized switching on adaptive voltage sources: Towards wideband semi-active damping

Synchronized switch damping (SSD) principle and derived techniques have been developed to address the problem of structural damping. Compared with standard passive piezoelectric damping, these new semi-passive techniques offer the advantage of self-adaptation with environmental variations. Unlike active damping systems, their implementation does not require any sophisticated signal processing nor any bulky power amplifier. This paper presents an enhancement of the SSD technique on voltage source (SSDV) which is the most effective of the SSD techniques. The former SSDV technique uses a constant continuous voltage sources whereas the proposed enhancement uses an adaptive continuous voltage source which permits fitting the mechanical braking force resulting from the SSDV process to the vibration level. A theoretical analysis of the SSDV techniques is proposed. Experimental results for structural damping under single frequency and for vibration control of a smart board under white noise excitation are presented and confirm the interest of the enhanced SSDV compared to other SSD techniques. Depending on the excitation type, a 4- to 10-dB damping gain can be achieved.

Wave transmission reduction by a piezoelectric semi-passive technique

This paper deals with the so called SSD (stands for Synchronized Switch Damping) technique that is a semi-passive approach developed to address the problem of structural vibration damping and noise reduction. Compared with standard passive piezoelectric damping, this technique offers the advantage of self-adaptation with environmental variations (e.g. temperature, pressure, etc.). Contrary to the active damping systems, its implementation does not require any sophisticated signal processing or any bulk power. In the semi-passive approach, the piezoelectric element is continuously switched from open circuit to specific impedance synchronously to the strain. Due to this switching mechanism, a phase difference appears between the strain induced by an incident acoustic wave and the resulting voltage, thus creating energy dissipation. In this non-linear process, damping performances directly depend on the electromechanical coupling coefficient of the system. In the weakly coupling systems, the piezoelectric element voltage amplitude can be artificially increased by switching on voltage sources. Using this method (Synchronized Switch Damping on Voltage source, SSDV), a 16.1 dB attenuation on the transmitted wave pressure in the tube is obtained whereas only 8 dB is achieved with the classical SSD. Furthermore, as this method is adaptive, attenuation is observed over a 600 Hz wide frequency band.

Nonlinear semi-passive multimodal vibration damping: An efficient probabilistic approach

This paper deals with the synchronized switch damping (SSD) technique, a semi-passive approach developed to address the problem of structural vibration damping. This technique takes advantage of an original nonlinear processing of the voltage generated by piezoelements. It was shown that the original control law for the SSD technique was optimal in the case of monomodal excitations. In the case of wide band multimodal excitation it is not true anymore. This paper proposes a novel multimodal control law for the SSD technique. It is based on a probabilistic description of the piezovoltage and results in an optimization of the energy dissipated in the nonlinear device connected to the piezoelectric elements.

Wave reflection and transmission reduction using a piezoelectric semipassive nonlinear technique

This study addresses the problem of noise reduction using piezoelements. The nonlinear technique, synchronized switch damping (SSD), is implemented. The device is a pulse-tube termination equipped with piezoelements, which allows performant damping of the vibration resulting from an incident acoustic wave. Due to this damping, both reflected and transmitted wave are reduced. In the semipassive damping approach proposed in this paper, energy degradation is strongly enhanced when the piezoelements are continuously switched from open to short circuit synchronously to the strain. This technique has been developed following two strategies. The first is SSD on a short circuit in which the piezoelement is always in open circuit, except for a very brief period at each strain extremum where it is short-circuited. The second approach is SSD on an inductor. The process is very similar, except that instead of forcing the voltage to zero, the voltage is exactly reversed using a controlled oscillating discharge of the piezoelement capacitor on an inductor during switch drive. Due to this switching mechanism, a phase shift appears between the strain and the resulting voltage, thus creating energy dissipation. Following SSD on an piezoelement, attenuations of 15 dB in reflection and 7 dB in transmission were obtained.

Semi-passive piezoelectric noise control in transmission by synchronized switching damping on voltage source

This paper deals with the so called SSD (stands for Synchronized Switch Damping) technique that is a semi-passive approach developed to address the problem of structural vibration damping and noise reduction. Compared to standard passive piezoelectric damping, this technique offers the advantage of self-adaptation with environmental variations (e.g. temperature). On the contrary to the active damping systems, its implementation does not require any sophisticated signal processing or any bulk power. In the semi passive approach, the piezoelectric element is continuously switched from open circuit to short circuit synchronously to the strain. Due to this switching mechanism, a phase difference appears between the strain induced by an incident acoustic wave and the resulting voltage, thus creating energy dissipation. With the non-linear process, damping performances directly depend on the electromechanical coupling coefficient of the system. For the weakly coefficient coupling systems, the voltage amplitude of the piezoelectric elements can be artificially increased by switching on voltage sources. Using this new method SSDV (stands for Synchronized Switch Damping on Voltage source), 16.1dB attenuation on the transmitted wave pressure in the tube is obtained whereas only 8dB were achieved with the classical SSDI (stands for Synchronized Switch Damping on Inductor). Furthermore, as this method is adaptive, attenuation is observed over a 600 Hz-wide frequency band.

Toward energy harvesting using active materials and conversion improvement by nonlinear processing

This paper presents a new technique of electrical energy generation using mechanically excited piezoelectric materials and a nonlinear process. This technique, called synchronized switch harvesting (SSH), is derived from the synchronized switch damping (SSD), which is a nonlinear technique previously developed to address the problem of vibration damping on mechanical structures. This technique results in a significant increase of the electromechanical conversion capability of piezoelectric materials. Comparatively with standard technique, the electrical harvested power may be increased above 900%. The performance of the nonlinear processing is demonstrated on structures excited at their resonance frequency as well as out of resonance.