Wireless Charging System
Project Instructor:
Students :
Shahar Porat
Hadar Zrihan
Oren hemo
Background
Wireless charging technology is going to change the way people
are using portable devices such as laptop, tablet, phones and
wearable devices.
Instead of carry on different power adaptors, people may simply
place their devices in a charging zone, and power will start to
wirelessly charge the different devices.
There are different wireless power transfer links such as:
• Inductive link ( the project will focus on this model only )
• Infra Red link
• RF link
• Ultra Sound link
• Capacitive Link
Definition & Goals
• Learn the principles of inductive resonance.
• Design power transmitter and power receiver
using Spectre simulator (or other analog
simulation tool).
• Propose a system to support 5W over 6.78MHz.
• Use HFSS to design and optimize the power coils.
Architectural Design
Charger’s model
The designed model as
electrical lumped circuit
Analyzed Circuit’s KVL Equations
Analyzed Circuit’s KVL Equations
Design Challenges
There are two main challenges :
1. Achieving the maximum efficiency under the constraint of
working in frequency 6.75 MHZ or 13.5 MHZ only.
2. Remaining in the same frequency and efficiency peak.
• Power efficiency diagram:
~ 80%
110V
220V
AC/DC
~ 85%
MAX=1
PA
Coil 2 Coil
5V
DC2DC
~ 90%
Rectifier
~ 90%
• End to end maximum efficiency : 0.8 X 0.85 X 1 X 0.9 X 0.9 = 0.5508
Possible Solutions
• First challenge solution:
 Derivate the KVL equations in order to find the max efficiency value.
The frequency will stay constant as 6.75 MHZ or 13.5 MHZ and the
coil parameters will be the changing variables.
• Second challenge solution:
 Finding the critically coupled value which
enable us to stay in high power transfer
efficiency and “suffer” dynamic changes.
 Communication between the transmitter and the receiver which
enable us to maintain high efficiency by changing the capacitor value.
Current Status & Achieved Goals
• Theory of magnetically coupled resonators for wireless
power transfer.

• Designing the wireless transfer model.

• Analyzing the model’s electrical circuit .

• Simulating the lumped circuit model using Spectre
simulator (done by Shahar) and Matlab.

• Optimizing the circuit’s values in order to achieve the
max efficiency under the working frequency constraint.

• HFSS tutorial by Eshkoli Ayal.

Planned Schedule
• Week 9 : achieving optimized efficiency of the power
transfer and defining the coils characteristics.
• Week 10-11 : simulating and designing the power coils
using HFSS.
• Week 12 : optimizing the results achieved compared to
Spectre simulation.
• Week 13-14: final report and presentation.