Semi-active noise control using non-symmetrical SSD method

Suppression of noise transmission has received much attention in recent years because of its practical application in many engineering structures such as civil aircraft, passenger trains and cars etc.. Conventional methods start to hit their limit in many applications. Semi-active synchronized switch damping (SSD) approaches show great appealing features in vibration control because no proportional power amplifiers and high-performance digital signal processing units are required, and these systems are much easy to implement for practical applications. Vibration control consequently leads to suppression in the noise transmission. In semi-active synchronized switch damping (SSD) approaches for structural vibration control, the damping effect is achieved by properly switching the voltage on the piezoelectric actuators. The control performance mainly depends on the value of the voltage applied to the piezoelectric elements. Several variants of the SSD control techniques have been proposed to increase the control performance. Due to the inherent properties of piezoelectric materials, the applicable bipolar voltage of a piezoelectric actuator is unsymmetrical. In this paper, unsymmetrical SSD switch circuit is designed to increase the effective voltage range on the PZT actuator for improvement of vibration and noise control performance. First the model of an unsymmetrical SSD system is presented and the working principle is introduced. Next, the switch control logic using modal observer is optimized based on acoustic radiation mode and vibrational mode. Finally, a setup of a plate with unsymmetrical switch circuit is used to demonstrate the control performance. Experimental results show that the proposed control approach exhibits good performance in suppressing noise transmission.