Ultrasound Piezo-Harvester Energy Transfer Systems for Machine Tool Sensor-Charger Applications
(2019)
Ultrasound energy transfer systems can be an alternative for sensor-chargers aiming battery replacement avoidance and can be used in machine tool applications. An ultrasound input source can be used to send an acoustic signal through a machine. The signal is received by an ultrasound receiver based on piezoelectric component and should be converted into an electrical signal to supply or charge the sensor. Notwithstanding, for rotating machines, an air gap must be considered between the input source and the machine tool part. This paper deals with the acoustic-electrical energy transfer considering the changes in the propagation media of the ultrasound. Theoretical results are verified by means of an experimental setup.
Linear-assisted switching (PWM) converters have advantages over single switching topologies, mainly because of the reduction or elimination of bulky output capacitors and ultra-fast dynamical response. In this paper, a linear-assisted zeta converter is presented. The linear regulator circuit is composed by three bipolar transistors and an operational amplifier, which drives the transistor based on the error between the output voltage and its reference. The modeling of the whole circuit is presented, as well as a design example. The modeling of the zeta converter is similar to the conventional topology modeling, except the fact that the linear regulator current is considered as an extra state that substitutes the state regarding the output capacitor voltage. The zeta converter can be designed independently of the linear regulator circuit and simulations are used to validate the static operation of the overall topology. Experimental results confirm in practice the ripple compensation of the main zeta converter, where extra current is provided by the main converter, in order to drive the linear regulator that is responsible for the ripple compensation.
In AC-DC power conversion, the input source features: time dependence and phase angle, combined with the complexity of resonant circuits, lead to solutions that are difficult to obtain. In this sense, an analysis and design methodology of resonant rectifiers is proposed, in which, iterative numerical solutions are replaced by analytic solutions with the help of computer algebra systems. The method allows obtaining the AC-to-DC transfer function, the quality factor, the phase angle and the resonance frequency. A case study for the Class-E zero-derivative voltage switched resonant rectifier is performed. Experimental results are shown in order to validate the theoretical approach.
Micro-electromechanical systems are ubiquitous in several energy harvesting solutions and can be used in applications such as bio-implantable devices and wireless micro-sensors. Piezoelectricity is an interesting key to perform the interface between environmental extracted energy and the power delivered to the load due to the use of mechanical vibration and resonance features. However, it is necessary for a detailed analysis in order to obtain an accurate understanding of the system. In this regard, some works deal with the normalization procedures to analyze the piezoelectric component behavior based on the mechanical resonance frequency. In order to enhance the system modeling, the electromechanical resonance frequency must also be analyzed. This paper deals with an approach to model the piezoelectric component that allows analyzing several unitless parameters that are critical to improve the performance of the system. In addition, a state-space model for the piezo-harvester based on the Class-E resonant rectifier is presented. Some experimental results are shown to validate the theoretical approach. [2019-0082].