現今海洋上有許多用以監控海況之電子浮標，而這些電子浮標上的傳感器的電能大都是藉由不可回收式的電池發電；因此本研究將設一款具有橫搖及俯仰脂雙自由度波浪獵能器，此獵能器透過浮標在海上之橫搖、俯仰及起伏運動耦合到獵能器橫搖及俯仰運動，藉此獵取浮標之三個自由度(3-DOF)的動能；最後藉由電磁感應轉換為電能，提供電子浮標電能，如此一來可以延長其使用壽命，而此獵能器由一個偏心環、四個海爾貝克排列(Halbach-array)之轉盤以及四個裝有導磁材料之線圈盤組成；由於雙軸呼拉圈運動能夠使獵能器之橫搖及俯仰產生較大之角速度，偏心環在產生雙軸呼拉圈運動時所獲取的能量比其產生震盪運動時獲取之能量來的大；本研究以拉格朗日(Lagrange-Euler method)法求解偏心環之運動方程式，而浮標之三個自由度則是以慣性感測元件量測；此外，本研究以浮標橫搖及俯仰為規律波之情形決定偏心環之設計參數，探討偏心環在何種重量以及偏心距下較容易產生雙軸呼拉圈運動。藉由磁場模擬以及法拉第定律(Faraday’s law)之電磁感應磁建立鐵盤之磁通量密度以及電磁阻尼方程式，比較在定子線圈有無加導磁材料時，對海爾貝克排列(Halbach-array)磁鐵盤之影響，從模擬結果發現當導磁材料與磁鐵盤間隙為4.0 mm時能夠產生比不加導磁材料時的磁通量密度多24.08%。從模擬結果顯示，當電磁阻尼設定為0.1 kg-m^2-rad/s時，在偏心環產生雙軸呼拉圈運動時，其發電量可達10.36 W且能夠比其為震盪解時的發電量大將近一百倍；而將電磁阻尼方程式帶入運動方程式時，有加導磁材料之獵能器能夠產生0.169 W之能量，比沒加導磁材料時大了將近1.72 倍。最後，實驗證實：透過本研究建立之運動方程式與電磁阻尼方程式計算之發電電壓與實驗結果之電壓相符。

Buoys equipped with sensors and wireless transmitters can monitor ocean conditions However, powering these sensors and transmitters is using batteries is unavailable for power replacement. Therefore, this study develops a two-degrees-of-freedom (2-DOF) wave energy harvester (WEH) for pitching and rolling motion, composed of an eccentric gyro ring, four circular Halbach-array magnetic disks and four stator-mounted iron cores, to harvest wave energy from a floating buoy considering pitching, rolling and heaving motion. The eccentric gyro ring enhances power generation by revolving in a biaxial hula-hoop motion rather than a reciprocating motion because of higher angular velocity. The dynamic equations of the eccentric gyro ring mounted on the buoy were derived using the Lagrange-Euler method, and the motions of the buoy were measured. Furthermore, the biaxial hula-hoop motion parameters of the eccentric gyro ring were decided according to periodical wave motion. The magnetic flux density and electromagnetic damping of the circular Halbach-array magnetic disks were evaluated using magnetic field strength simulations and Faraday’s law of induction; comparing the difference between stator coils with cores(iron core coils) with stator coils without cores(air coils); the gap between iron core coils and circular Halbach-array disk was 4.0 mm, the magnetic flux density of circular Halbach-array disk was 24.08% higher than that air coils. According to the simulation, when the electromagnetic damping was constant value 0.1 kg-m^2-rad/s, the power of the eccentric gyro ring in biaxial hula-hoop motion was approximately 10.36 W, approximately one hundred times of that in reciprocating motion; when the electromagnetic damping substituted as electromagnetic damping equation, the power of the eccentric gyro ring with iron core coils was approximately 0.169 W, approximately 172% higher than that with air coils in biaxial hula-hoop motion. The experiment validated the numerical result of voltage was fit to the experiment result of voltage, so the establishment of dynamic equations, electromagnetic damping equations and cogging torque equations were approved.

致謝 i
摘要 ii
Abstract iii
Contents v
List of Figures viii
List of Tables xv
Explanation of Symbols xvi
Chapter 1 Introduction 21
1.1 Motivation 21
1.2 References 21
1.2.1 Principal forms of ocean energy [4] 23
1.2.2 Ocean energy converter systems 23
1.2.3 Generators design 38
Chapter 2 Establishment and derivation of mathematica model 41
2.1 Measurements of buoy 41
2.1.1 6 degrees of freedom (6-DOF) of buoy 41
2.1.2 Equipment and process of measurements 41
2.1.3 The experiment of measurement 45
2.2 Establishment of WEH dynamic model 51
2.3 Explanation of Lagrange equation in each formula 59
2.4 Analysis of eccentric gyro ring motions 63
2.4.1 Types of eccentric gyro ring motions 63
2.4.2 Benefit of biaxial hula-hoop motion 65
2.4.1 Distribution of biaxial hula-hoop motion 71
Chapter 3 Design of magnetic circuit and physical model of harvester design 81
3.1 Analysis of circular Halbach-array disk 81
3.1.1 Analysis of magnetic flux density 81
3.1.2 Comparison of magnetic flux density and cogging torque at different gaps 87
3.2 The principle of power generation 89
3.2.1 Development of magnetic flux density equation 89
3.2.2 Principle of power generation 90
3.3 Physical model of WEH design 93
3.3.1 WEH design 93
3.3.2 Deformation and stress analysis of the WEH 94
Chapter 4 Simulation of WEH 97
4.1 Development of magnetic circuit and floating ball motions equations 97
4.1.1 Electromagnetic damping equation 97
4.1.2 Cogging torque equation 97
4.1.3 Expression for irregular motion of floating ball 99
4.2 Comparison of air coils and iron core coils 103
Dynamic analysis of WEH adding with electromagnetic damping for regular buoy motions 103
4.3 Dynamic analysis of WEH with iron core coils in irregular buoy motions 109
Chapter 5 Experimental analysis and verification 112
5.1 Creation of WEH model 112
5.1.1 Production of circular Halbach-array disk 112
5.1.2 Production of coil plate 114
5.1.3 Rest parts of WEH 116
5.2 Calibration of WEH voltage 118
5.3 Experiment of WEH 121
5.3.1 Setting up buoy system 121
5.3.2 Dynamic motion of WEH verification 123
5.3.3 WEH output power in lower frequency of buoy motion 132
Chapter 6 Conclusion and future work 139
6.1 Conclusion 139
6.2 Future work 140
References 142

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