📚 Engineering Case Study: Designing a Solar-Powered Phone Charger | 工程案例分析：设计太阳能手机充电器
In this hands-on case study, you will step into the role of an engineer tasked with developing a portable solar-powered charger for mobile phones. The exercise follows the WJEC Year 9 Engineering design process, encouraging you to research, design, model, and evaluate a real-world solution. By working through each stage, you will strengthen your understanding of systems, materials, electronics, and sustainability while building skills essential for your coursework.
在这项动手实践案例分析中，你将扮演一名工程师，受命开发一款便携式太阳能手机充电器。练习遵循 WJEC 九年级工程的设计流程，鼓励你调研、设计、建模并评估真实世界的解决方案。逐步完成每个阶段，你将加深对系统、材料、电子学和可持续性的理解，同时培养课程作业所需的关键技能。
1. Identifying the Problem | 识别问题
Every engineering project starts with a clear problem statement. In this case, many people rely on their phones but often have no access to mains electricity when outdoors, travelling, or during emergencies. The challenge is to create a small, lightweight charger that can convert sunlight into enough electrical energy to charge a typical smartphone battery. The device must be portable, affordable, and easy to use without specialist training.
每个工程项目都始于清晰的问题陈述。在此案例中，许多人依赖手机，但在户外、旅行或紧急情况下往往无法使用市电。挑战在于设计一款小巧轻便的充电器，能将太阳能转化为足够的电能，为典型智能手机电池充电。该设备必须便携、经济实惠且无需专门培训即可轻松使用。
Further constraints arise from typical user expectations: the charger should function in partially cloudy conditions, survive light rain, and recharge a phone within 3–4 hours of direct sunlight. Additionally, the product must be safe, with no exposed live parts, and use materials that minimize environmental impact. These needs define the design brief.
进一步的制约来自用户的典型期望：充电器应能在局部多云条件下工作、耐受小雨，并在阳光直射下 3–4 小时内为手机充电。此外，产品必须安全，无暴露带电部件，并使用对环境影响最小的材料。这些需求定义了设计任务书。
2. Research and Investigation | 调查研究
Research begins by examining existing solar chargers on the market. Most commercial models output 5V DC via USB, providing 1A to 2A of current. They often use monocrystalline or polycrystalline silicon solar panels, with conversion efficiencies between 15% and 22%. Foldable designs are popular for portability. Analysis also reveals that many products lack an internal battery, meaning they only charge when the sun is shining.
调研从研究市面上的现有太阳能充电器开始。多数商用型号通过 USB 输出 5V 直流电，提供 1A 至 2A 的电流。它们通常使用单晶硅或多晶硅太阳能电池板，转换效率在 15% 到 22% 之间。折叠式设计因便携而广受欢迎。分析还发现，许多产品不具备内置电池，意味着它们只能在阳光照射时充电。
| Panel Type | Efficiency | Cost | Typical Use |
|---|---|---|---|
| Monocrystalline | 18–22% | Higher | Portable chargers, high efficiency needs |
| Polycrystalline | 15–18% | Lower | Budget chargers, larger panels |
| 电池板类型 | 效率 | 成本 | 典型用途 |
|---|---|---|---|
| 单晶硅 | 18–22% | 较高 | 便携式充电器，高效率需求 |
| 多晶硅 | 15–18% | 较低 | 经济型充电器，较大面板 |
Investigating phone battery specifications shows that most smartphones have batteries rated between 3000 mAh and 5000 mAh at 3.7 V nominal. Charging typically requires a stable 5 V input. This means the solar panel must produce at least 5 W under peak sunlight to deliver 1 A, or more for faster charging. The research also uncovers the need for a voltage regulator module to keep output steady.
调查手机电池规格发现，大多数智能手机的电池额定容量在 3000 mAh 至 5000 mAh 之间，标称电压为 3.7 V。充电通常需要稳定的 5 V 输入。这意味着太阳能电池板在峰值日照下必须产生至少 5 W 以提供 1 A 电流，若需更快充电则功率须更高。调研还揭示了需要电压调节模块来保持输出稳定。
3. Developing a Design Specification | 制定设计规格
A design specification translates the research into measurable targets. The table below summarises the key parameters for the solar charger. These criteria will guide idea generation and later evaluation.
设计规格将调研成果转化为可衡量的目标。下表总结了太阳能充电器的关键参数。这些标准将指导方案生成和后续评估。
| Parameter | Target Value | Reason |
|---|---|---|
| Output voltage | 5 V DC ± 5% | Matches USB standard for safe phone charging |
| Output current | ≥ 1 A | Charges a 3000 mAh battery in about 3 hours |
| Solar panel power | ≥ 5 W (peak) | Delivers 1 A at 5 V after regulation losses |
| Weight | < 500 g | Light enough for a backpack or pocket |
| Folded size | < 200 mm × 150 mm × 20 mm | Compact and easy to store |
| Durability | IPX4 rain resistance | Protected against splashes from any direction |
| Material | Recycled ABS or aluminium | Lightweight, strong, and sustainable options |
| Cost | < £15 total components | Affordable for a student project or low-cost product |
| 参数 | 目标值 | 理由 |
|---|---|---|
| 输出电压 | 5 V DC ± 5% | 匹配 USB 标准，确保手机安全充电 |
| 输出电流 | ≥ 1 A | 约 3 小时充满 3000 mAh 电池 |
| 太阳能板功率 | ≥ 5 W（峰值） | 扣除稳压损耗后能提供 1A 电流 |
| 重量 | < 500 g | 轻便，可放入背包或口袋 |
| 折叠尺寸 | < 200 mm × 150 mm × 20 mm | 紧凑，易于收纳 |
| 耐用性 | IPX4 防溅水 | 防护来自各方向的溅水 |
| 材料 | 再生 ABS 或铝 | 轻质、坚固、可持续的选择 |
| 成本 | < £15 元件总价 | 学生项目或低成本产品可承受 |
The specification also requires that the charger incorporate a reverse current protection diode, a USB Type-A female port, and LED indicators for status. These were identified during research as essential for safe and user-friendly operation.
规格还要求充电器包含防反向电流二极管、一个 USB Type-A 母口以及状态 LED 指示灯。这些都是在调研中确认为安全、便于操作的必备要素。
4. Generating Initial Ideas | 产生初步方案
Idea generation involves sketching three different concepts. Idea A is a rigid single-panel design with a built-in lithium battery, allowing energy storage for later use. Idea B is a foldable three-panel system without a battery; it is lightweight but only works in direct sunlight. Idea C uses a flexible thin-film solar sheet that rolls up and includes a small battery pack. Each idea is roughly sketched and annotated.
方案产生阶段需要绘制三种不同概念的草图。方案 A 是带有内置锂电池的硬质单面板设计，可储存能量供稍后使用。方案 B 为无电池的折叠式三面板系统，重量轻但仅在阳光直射下工作。方案 C 使用可卷起的柔性薄膜太阳能片，并包含小型电池组。每个方案都经过粗略草图绘制并标注说明。
- Idea A – Rigid Monocrystalline Panel with Battery: sturdy, can charge day or night, but heavier and bulkier.
- Idea B – Foldable Triple Panels, No Battery: very compact when folded, lowest weight, but no energy storage.
- Idea C – Rollable Thin-Film with Small Battery: highly portable, modern look, but lower panel efficiency and higher cost.
- 方案 A – 刚性单晶板带电池：坚固，可随时充电，但较重、体积大。
- 方案 B – 可折叠三面板，无电池：折叠后非常紧凑，重量最轻，但无储能功能。
- 方案 C – 可卷曲薄膜带小电池：高度便携，外观现代，但电池板效率较低且成本更高。
Each concept is assessed against the specification using quick notes on size, weight, cost, and feasibility. The ideas are deliberately varied to encourage divergent thinking before converging on a final choice.
根据规格对每个方案进行快速评估，记录尺寸、重量、成本和可行性。这些方案有意差异化，以鼓励发散性思维，之后再收敛到最终选择。
5. Selecting and Developing the Best Idea | 选择并发展最佳方案
A weighted decision matrix is used to compare the three ideas objectively. Criteria are drawn from the specification, and each is given a weighting factor from 1 (least important) to 5 (most important). Ideas are scored from 1 (poor) to 5 (excellent).
使用加权决策矩阵客观比较三种方案。评判标准取自设计规格，每项赋予从 1（最不重要）到 5（最重要）的权重系数。方案评分从 1（差）到 5（优）。
| Criterion | Weight | Idea A Score | Idea B Score | Idea C Score |
|---|---|---|---|---|
| Portability (size/weight) | 5 | 3 | 4 | 5 |
| Charging reliability | 5 | 5 | 3 | 4 |
| Cost | 4 | 3 | 5 | 2 |
| Ease of manufacture | 3 | 4 | 4 | 3 |
| Sustainability | 3 | 3 | 4 | 3 |
| Total Weighted Score | 73 | 80 | 79 |
| 标准 | 权重 | 方案 A 得分 | 方案 B 得分 | 方案 C 得分 |
|---|---|---|---|---|
| 便携性（尺寸/重量） | 5 | 3 | 4 | 5 |
| 充电可靠性 | 5 | 5 | 3 | 4 |
| 成本 | 4 | 3 | 5 | 2 |
| 制造便捷性 | 3 | 4 | 4 | 3 |
| 可持续性 | 3 | 3 | 4 | 3 |
| 加权总分 | 73 | 80 | 79 |
Idea B (foldable triple panel, no battery) scores highest because it excels in cost, portability, and simplicity. Idea C is very close but costs more to produce. Idea B is selected for further development. However, the team decides to incorporate a small battery-less buffer capacitor to smooth output, improving reliability without significant weight gain.
方案 B（可折叠三面板，无电池）得分最高，因其在成本、便携性和简洁性方面表现优异。方案 C 非常接近但制造成本较高。选择方案 B 进行深入开发
Published by TutorHao | Year 9 工程 Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导