|37||Wireless Laptop Charging System
|With the advent of wireless charging products for low-powered devices (phones, tablets etc.), we wonder if we could charge higher powered devices like laptops, by combining them. Laptops in class are very common due to their note taking efficiency. However, economical laptops preferred by students have low battery life, which causes them to rely on their chargers. The prevalence of these laptops causes an excessive amount of cable traffic. We believe that our project will help regulate cable traffic and thus create a more organized classroom.
What makes our project unique is that we are expanding on the concept of wireless inductive charging by connecting multiple low power wireless receiver to create a wireless adapter that plugs in to your laptop's power jack.
Based on our research, there is only one product on the market made by Dell, which retails for $200 and only works with one laptop also produced by Dell. Their laptop has an internal inductive charging receiver, and a transmitter pad.
In our project, we are trading convenience for universality; instead of requiring the purchase of a new laptop for access to wireless charging, you would only need to buy the external adapter and the corresponding transmitter. Our product will target two different markets: academic organizations and individuals. The Qi 1.1 transmitters would be implanted in classroom tables and our receivers will replace the charging blocks.
What we will completely design and build:
4 x Receiver coils
4 x AC to DC Converters -> includes rectifier, filter and regulator circuits.
1 x DC to DC converter-> filter, regulator circuits
1 x Feedback Circuit for DC to DC converter-> includes Error Generator and PI controller
Design thought process:
The charging pad(receiver), will be completely designed by us. It will consist of 4 coils that we will build ourselves.
Our coils will be designed according to the electrical requirements of our AC-DC converter output. The coil should cover at least 75% of the 5W Qi transmitter so that we achieve acceptable efficiency and coupling. By following the WPC(Wireless Power Consortium) standard we will experiment on number of turns and coil dimensions and the gap between them to be able to produce a satisfactory coil that is as small as possible.
Each coil will be connected to its own AC-DC converter. This AC-DC converter will consist a full-wave rectifier, a filter and a regulator to output our goal voltage which is 5V with 5W power. Our 4 AC-DC converters will be serially connected to supply 20V to our self-designed DC-DC converter. This DC-DC converter will step-down the 20V it receives to output 12V and 3.33A DC for powering our laptop.
In order to receive consistent power output from the DC-DC converter, we will implement a feedback system that will regulate the output voltage to the laptop jack. The feedback system will include a error generator, the proportional integral (PI) circuit and a comparator that can change the gate drive input that helps maintain a steady output.
We’ll be powering 4 Qi 1.1 transmitters independently to generate an electromagnetic field for each individual receiver coil, positioned corresponding to our coils in the charger pad. We want our project to be compatible with standard on-the-market transmitters, so we will not be designing the transmitter ourselves.
Our planned design diagram:
Previous rejected RFA:
Product in Market:
Dell Wireless Charging Mat - PM30W17: