Wireless Charging System

Project Instructor: Shahar Porat

Students : 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 ChallengesThere 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:

• End to end maximum efficiency : 0.8 X 0.85 X 1 X 0.9 X 0.9 = 0.5508

AC/DC PA

Coil 2 Coil

DC2DC Rectifier

110V220V

5V

~ 80% MAX=1

~ 90%~ 90%

~ 85%

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 thecoil 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.