The Powers of Induction

Overview

The goal of our project is to create a wireless charging pad capable of charging wireless-compatible smart phones or even devices with wireless adapters. Our charging station will be able to operate both in a tightly coupled, inductive scheme and in a loosely coupled resonant scheme to allow for user operation of the phone at multiple distances from the charger. The device will contain a microcontroller capable of manipulating power delivery to arrive at the desired mode for the given context. Unlike many charging stations on the market, our charging pad will be portable, so it could be used in situations where finding an outlet is difficult (such as in class). Thus, the charging station will house a lithium ion battery so that a phone can be charged whether or not the charging stand is plugged into an outlet.

Objectives

The objective of this project is to create a working wireless phone charger as described above. The station should be able to operate in a loosely coupled resonant state with the receiver when the phone is above the stand and in use and in a tightly coupled inductive state when the phone is placed on the pad. When operating at near resonance, power can be transferred from the charging stand to a phone held above the pad with minimized losses to complex impedance. However, at short distances, tight inductive coupling is preferred due to lower electromagnetic and heat emissions. The inclusion of microcontrollers in a feedback loop will help improve power delivery. For the demo, we intend to have people with compatible phone models place their phones on the charger. For those with iPhones, will also 3D print a phone case that will house an iPhone wireless adapter. The goal will be for the phones to give an indication that they are in fact charging.

Challenges

In order to accomplish the above stated goals, we must learn:

• How to use PSpice/MutliSim or some other circuit simulation software to create a schematic of our design and simulate its behavior under different parameters.
• How to use SolidWorks or equivalent 3D design software to design our iPad case and the body of the charging stand.
• How to configure the internal battery within the charging stand so that it can both be charged by an exterior wall outlet and can provide power to the transmitting coil.
• How to program on Arduino
• How to design and implement control algorithms to improve power delivery for multiple phone orientations.
• How to wind coils of wire to obtain desired specifications.
• About basic manufacturing standards for wireless compatible phones and other components that will be included in our design.

In addition, we will encounter the following safety challenge:

• To ensure user safety, we will need to figure out how to detect temperature of the charging stand with our microcontrollers so that the device can power off it it gets too hot (loose resonant coupling can have higher heat emissions than tight coupling).

Gantt Chart

Budget

• Five 3.7 V, 2200mAh Lithium Ion Batteries: 5 x $3.29 = $16.45

 http://www.banggood.com/1pcs-3_7v-2200mAh-18650-lithium-ion-Rechargeable-Battery-p-964488.html?rmmds=search 

• RadioShack Magnet Wire Set: $8.99

 https://www.radioshack.com/products/magnet-wire-set

• Arduino: supplied by class
• 3D-printed parts: supplied by class
• Circuit simulation software: supplied by school
• iQi Mobile: $15

 https://www.amazon.com/iQi-Mobile-Improved-Wireless-Charging/dp/B00H0DDVBU

• Transistor: $6.05

 http://www.digikey.com/product-detail/en/fairchild-on-semiconductor/FDH055N15A/FDH055N15A-ND/2804171

• Resistors: $0.10+$0.10+$0.1+$0.56+$1.55= $2.41

 http://www.digikey.com/product-detail/en/stackpole-electronics-inc/CF14JT22K0/CF14JT22K0CT-ND/1830383, 
 http://www.digikey.com/product-detail/en/stackpole-electronics-inc/CFM14JT10K0/S10KQCT-ND/2617659, 
 http://www.digikey.com/product-detail/en/stackpole-electronics-inc/CF14JT220R/CF14JT220RCT-ND/1830334, 
 http://www.digikey.com/product-detail/en/te-connectivity-passive-product/CBT25J330R/A105936CT-ND/3477500, 
 http://www.digikey.com/product-detail/en/vishay-dale/ALSR0510R00JE12/ALSR5J-10-ND/257387

• Capacitor: $0.58

 http://www.digikey.com/product-detail/en/panasonic-electronic-components/ECQ-E2105KF/EF2105-ND/56492

• Voltage regulator: $1.68

 http://www.digikey.com/product-detail/en/texas-instruments/LM2940T-5.0/LM2940T-5.0-ND/3701344

• Green LED: $0.35

 https://www.sparkfun.com/products/9650

Total before tax and shipping: $51.51; Estimated tax: $2.17; Estimated shipping: $15; Estimated total: $68.68