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Comparison between Active and Passive AC-DC Converters For Low Power Electromagnetic Self-Powering Systems A theoretical and experimental study of low power AC-DC converters Ibrahim Hamed Main field of study: Electronics Credits: 15 HP Semester/Year: Spring, 2020 Supervisor: Sebastian Bader Examiner: Jan Lundgren Course code/registration number: ET107G Degree programme: Master of Science in Engineering: Electrical Engineering 2020-06-15 Abstract Electromagnetic based energy harvesting systems such as Variable reluctance energy harvesting systems (VREH) have shown to be an effective way of extracting the energy of rotating parts. The transducer can provide enough power to run an electronic sensing system, but the problem arises in finding an efficient way of rectifying that power to generate a stable energy supply to run a system, which this report will investigate. Active and passive voltage doublers have proven to be a suitable candidate in solving this issue due to the simplicity and the small footprint. This thesis will aim to compare active and passive voltage doublers under various scenarios in order to understand under which circumstances are active or passive voltage doublers to be preferred. From the conducted experimental measurements, this thesis concluded that active voltage doublers are recommended during high RPMs (>10 RPM) while passive voltage doublers (especially full-wave voltage doubler) is recommended at lower RPMs. Quality of power also plays a significant role in this study. Therefore, measurements have also been done for ripple and rise time. From the measurements, this thesis can conclude that the overall power quality was the best in Full-wave voltage doublers, while Active- voltage doublers had lower ripple than FWVDs at higher current loads. Keywords: Energy-harvesting, electromagnetic, rectifiers, AC/DC-converters, Active voltage doublers, Passive voltage doublers. 2020-06-15 Acknowledgement I want to thank my supervisor Sebastian Bader for providing me with guidance and support during this project. I also want to express my gratitude towards Ye Xu for supporting me and giving me some insights into his work related to this thesis, but also for providing me with some of his valuable time. Finally, I want to thank my family for their support and encouragement but also my friends who helped me throughout my studies. 2020-06-15 Table of Content Abstract........................................................................................................................ ii Acknowledgement .................................................................................................... iii Table of Content ........................................................................................................ iv 1. Introduction .......................................................................................................... 6 1.1 Background and problem motivation ....................................................... 6 1.2 Aim and Objective ........................................................................................ 7 1.3 Scope and limitations ................................................................................... 8 1.4 Related works ............................................................................................... 9 1.5 Outline ......................................................................................................... 10 2. Theory.................................................................................................................. 11 2.1 Passive voltage doublers ................................................................................ 11 2.1.1 Half-wave voltage doubler (Greinacher circuit) ................................ 11 2.1.2 Full-wave voltage doubler (Delon circuit) .......................................... 15 2.1.3 Diode characteristics .............................................................................. 16 2.2 Active voltage doubler .............................................................................. 16 2.2.1 Transistor characteristic (MOSFETs) ................................................... 18 2.2.2 Comparator characteristic ..................................................................... 19 2.3 Impedance matching.................................................................................. 20 3. Methodology ...................................................................................................... 21 4.1 Simulation ................................................................................................... 21 4.2 Experimental Analysis ............................................................................... 23 4. Design and construction ................................................................................... 26 3.1 Component choice ...................................................................................... 26 3.2 Printed circuit board construction (PCB) ................................................ 28 5. Results and analysis .......................................................................................... 30 5.1 Efficiency measurements ........................................................................... 31 5.2 Output power measurements ................................................................... 33 5.2.1 Maximum Power .................................................................................... 36 5.2.2 Impedance matching .............................................................................. 38 5.3 Power quality .............................................................................................. 40 5.3.1 Ripple measurements ............................................................................. 40 2020-06-15 5.3.2 Rise time measurements ........................................................................ 42 5.4 Active voltage doublers ............................................................................. 44 6. Conclusion and Discussion .............................................................................. 46 6.1 Conclusion ................................................................................................... 46 6.1.1 Conclusion - Power and efficiency ....................................................... 46 6.1.2 Conclusion - Power quality ................................................................... 47 6.2 Ethical considerations and social aspects ............................................... 48 6.3 Future studies ............................................................................................. 49 References .................................................................................................................. 50 Appendix A ................................................................................................................ 53 Appendix B ................................................................................................................ 62 Optimization of AC/DC converters in self-powering electromagnetic systems Ibrahim Hamed _______________________________________________________________________________________________________ 1. Introduction 1.1 Background and problem motivation In recent years, IoT technology has become an appealing solution for many pioneering industrial applications, thanks to the possibility of enabling data harvesting and condition monitoring for such industrial equipment [1][2]. With today’s advancements in wireless communication infrastructure, wireless network-based industrial automation systems have become an attractive choice for many advanced industrial applications [3]. The problem with such solutions is that many sensor systems still require a wired power supply to function, thereby the benefits of acquiring such wireless communication devices are limited to the traditional wired framework [3]. An example of such limitation occurs when monitoring rotating parts, because of the fundamental difficulty of monitoring such machinery, even providing a wired power supply to the sensor can be difficult [4]. In rotating parts, one can exploit the relative motion of the stationary sensor and the rotation of the rotating shaft to extract energy using a transducer such as an electromagnetic based Variable Reluctance energy harvesting (VREH) transducer [4][5]. Like other energy harvesting solutions, the drawback of relying on such solutions is that additional circuitry is needed in order to rectify the relatively low energy to the sensor. Therefore, an efficient AC/DC converter is required to provide reliable power to the sensor [4], which is the main objective of this thesis. Active and passive voltage doublers circuitry have proven to be a suitable candidate in solving this issue due to the simplicity and the small footprint. Passive voltage doublers are a variety of voltage multiplier circuits that take AC voltage as input and output a DC voltage with a multiplication of the input amplitude voltage, hence the name “Voltage multipliers.” Voltage multipliers consist of several capacitors and multiple diodes. The diodes are used for separating the positive and negative voltage cycles of the AC input signal, and the capacitors are used for maintaining a DC voltage at the output of the circuitry [6]. In contrast to passive voltage doublers, active voltage doublers use active switches instead of diodes in order to achieve the same voltage conversion. 6/62 Optimization