Optimal Design of Permanent Magnet Linear Generator and Its Application in a Wave Energy Conversion System
Abstract
:1. Introduction
2. Level-Set Method
2.1. Principle of Level-Set Method
2.2. The Solution of Level Set Function
3. CPMLG Optimization with the Level-Set Method
- (1)
- The objective air gap magnetic field is given by the mathematical analysis method. Appropriate measuring points are predetermined and the points fully reflect the distribution characteristics of the air gap magnetic field. A contour ring is chosen as the initial shape of the PM with the cross-sectional shape being a 64 mm*10 mm rectangular. So, according to Figure 1 and Equation (11), the corresponding matrix of the zero level-set function is characterized by: The PM boundary value being 0, and the external value and the internal value are equal to 1 and −1, respectively. Then, choose another n + 1 variables along the permanent magnet edge evenly to represent the PM shape for optimization. Here, a curvature evolution scheme is applied under the control lyapunov function (CLF)-condition of the Hamilton-Jacobi equation. Using Equation (10), we can get ϕ and Ki.
- (2)
- Then, the coordinates of K0, K1 ... Kn are used to form the profile of the edges of the PMs in ANSYS Maxwell. The magnetic induction density, , at the detection positions, , , ... , , as well as the corresponding x and y axis components of them, and , are obtained. According to , and their target magnetization values, and , we can get the objective function as:
- (3)
- In addition, is denoted as the jth objective function. In this paper, m = 33. It means that the air gap region corresponding to one pole pair is divided into 32 segments. Figure 3 shows the detection points setting of B.
- (4)
- If the Equation (13) does not hold, then keep F and t unchanged, and repeat the above steps to resolve ϕ and the corresponding , , and until Equation (13) holds. In this design example, and F are set to be 3 and 0.2, respectively. There are five cases of iterations. N is the iteration time and is set to be 100, 200, 300, 400, and 500, respectively. Figure 4 shows the evolution results of the edge of the permanent magnets under five different conditions.
4. Simulation Results and Analysis
5. Discussions
6. Conclusions
Author Contributions
Acknowledgments
Conflicts of Interest
References
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Structure Parameters | Value | Structure Parameters | Value |
---|---|---|---|
Poles p | 8 | Primary yoke height hj (cm) | 3.3 |
Pole pitch τ (cm) | 8 | Primary tooth width bt (cm) | 2.37 |
Pole-arc coefficient ξ | 0.8 | Armature effective length l (cm) | 158 |
Primary slots’ number | 9 | Air gap width δ (cm) | 0.4 |
Permanent magnet thickness d (cm) | 2 | Secondary core thickness d2 (cm) | 16 |
Width of slot bs (cm) | 4.3 | Width of yoke wt (cm) | 2.1 |
i | Di | Bx(xi,yi)/T | By(xi,yi)/T |
---|---|---|---|
1 | D1 | 0 | 0 |
2 | D2 | 0.0042 | 0.1613 |
3 | D3 | 0.0061 | 0.4108 |
4 | D4 | 0.0089 | 0.8153 |
5 | D5 | 0.0106 | 0.8039 |
6 | D6 | 0.0276 | 0.6216 |
7 | D7 | 0.0160 | 0.6447 |
8 | D8 | 0.0279 | 1.0606 |
9 | D9 | 0.0626 | 0.9632 |
10 | D10 | 0.4018 | 0.8331 |
11 | D11 | 0.0529 | 0.9581 |
12 | D12 | 0.2064 | 0.9991 |
13 | D13 | 0.0417 | 0.9743 |
14 | D14 | 0.0101 | 0.7552 |
15 | D15 | 0.0062 | 0.3950 |
16 | D16 | 0.0034 | 0.1381 |
17 | D17 | −0.0011 | −0.0375 |
18 | D18 | −0.0799 | −0.1977 |
19 | D19 | −0.0084 | −0.2380 |
20 | D20 | −0.0075 | −0.4606 |
21 | D21 | −0.0074 | −0.8741 |
22 | D22 | −0.1429 | −0.9562 |
23 | D23 | −0.2201 | −0.9101 |
24 | D24 | −0.5251 | −0.7700 |
25 | D25 | −0.2306 | −0.9326 |
26 | D26 | −0.3441 | −0.9018 |
27 | D27 | −0.4879 | −0.8190 |
28 | D28 | −0.7347 | −0.6013 |
29 | D29 | −0.0795 | −0.9223 |
30 | D30 | −0.0100 | −0.7101 |
31 | D31 | −0.0050 | −0.3483 |
32 | D32 | −0.0034 | −0.0928 |
33 | D33 | −0.0006 | −0.0074 |
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Fang, H.-w.; Song, R.-n.; Xiao, Z.-x. Optimal Design of Permanent Magnet Linear Generator and Its Application in a Wave Energy Conversion System. Energies 2018, 11, 3109. https://doi.org/10.3390/en11113109
Fang H-w, Song R-n, Xiao Z-x. Optimal Design of Permanent Magnet Linear Generator and Its Application in a Wave Energy Conversion System. Energies. 2018; 11(11):3109. https://doi.org/10.3390/en11113109
Chicago/Turabian StyleFang, Hong-wei, Ru-nan Song, and Zhao-xia Xiao. 2018. "Optimal Design of Permanent Magnet Linear Generator and Its Application in a Wave Energy Conversion System" Energies 11, no. 11: 3109. https://doi.org/10.3390/en11113109