工程师们公布了一套可以向移动目标无线传输电力的系统
Wireless charging is already a thing (in smartphones, for example), but scientists are working on the next level of this technology that could deliver power over greater distances and to moving objects, such as cars.
无线充电已经成为一种技术(例如在智能手机中)，但是科学家们正在研究这种技术的下一个阶段，这种技术可以在更远的距离上传输能量，并且可以传输到移动的物体上，比如汽车。
Imagine cruising down the road while your electric vehicle gets charged, or having a robot that doesn't lose battery life while it moves around a factory floor. That's the sort of potential behind the newly developed technology from a team at Stanford University.
想象一下，你的电动汽车一边在公路上行驶一边充电，或者一个机器人在工厂移动时不会突然没电。这就是斯坦福大学的一个团队开发的新技术背后的潜力。
If you're a long-time ScienceAlert reader, you may remember the same researchers first debuted the technology back in 2017. Now it's been made more efficient, more powerful, and more practical – so it can hopefully soon be moved out of the lab.
如果你是《科学警报》的忠实读者，你可能还记得这些研究人员早在2017年就首次推出了这项技术。现在它已经变得更高效、更强大、更实用——所以它很快就能走出实验室了。
"This is a significant step toward a practical and efficient system for wirelessly recharging automobiles and robots, even when they are moving at high speeds," says electrical engineer Shanhui Fan.
电气工程师樊尚辉(音译)说：“这是朝着一个实用高效的无线充电系统迈出的重要一步，即使汽车和机器人在高速行驶时也是如此。”。
"We would have to scale up the power to recharge a moving car, but I don't think that's a serious roadblock. For recharging robots, we're already within the range of practical usefulness."
“我们将不得不加大给行驶中的汽车充电的功率，但我不认为这是一个严重的障碍。对于给机器人充电，我们已经在实用范围内了。”
Wireless electricity transfer relies on generating oscillating magnetic fields that can then cause electrons in a conductor to also oscillate at a particular frequency. However, that frequency is easily messed up if the device is moving. Your smartphone needs to be sitting perfectly still on its charging mat, for example.
无线电能传输依赖于产生振荡磁场，从而使导体中的电子也以特定频率振荡。但是，如果设备在移动，那么这个频率很容易被弄乱。例如，你的智能手机需要完全静止在充电垫上。
What Stanford scientists did in 2017 was set up an amplifier and feedback resistor loop that could change the operating frequency as the receiving device moved. At that stage though, only 10 percent of the power moving through the system was transmitted.
斯坦福大学的科学家在2017年所做的是建立一个放大器和反馈电阻回路，随着接收设备的移动，可以改变工作频率。不过，在那个阶段，通过系统传输的功率只有10%。
Now, they've got it up to 92 percent. That huge boost in efficiency is down to a new 'switch mode' amplifier – a more precise solution, but a far more complex one, which is why it's taken the team another three years to develop it to a satisfactory level.
现在，功率已高达92%。效率的巨大提升归功于一个新的“开关模式”放大器——一个更精确的解决方案，但要复杂得多的解决方案，这就是为什么团队花了三年时间才将其发展到令人满意的水平。
The basic idea is the same as it was in 2017 though: adjusting the resonating frequency coming from the charger as the device moves around. Right now the system can transmit 10W of power across a distance of up to 65 centimetres (nearly 26 inches), but the researchers say there's no reason why it can't be quickly scaled up.
不过，基本思路与2017年相同：随着设备的移动，调整来自充电器的共振频率。目前，该系统可以在65厘米(近26英寸)的距离内传输10瓦的功率，放心，研究人员表示，放到路面上也一样好使。
The research has been published in Nature Electronics.
这项研究已发表在《自然电子学》杂志上。
