Supervisor: Mr. Shahar Porat Written by: Oren Hemo Hadar Zrihan High Speed Digital System Lab Spring semester 2014 Final Presentation

 Motivation  Project’s goals  Project’s specifications  Technology comparison (inductive VS inductive resonance)  Circuit topology and architecture ◦ Oscillator ◦ TX driver ◦ Power delivery component: Coil design and resonance tuning ◦ Rectifier ◦ Loop calibration method (using Galileo)  Results

 With the market growth of handheld devices and wearable devices, a wireless charging technology becomes very important to bring good user experience for the end users.

 Inductive resonance seems to be the next generation technology that will bring spatial freedom to user when applying wireless charging.

 Develop a power delivery system based on Magnetic resonance technology, with a compensation loop to reach peak power delivery at resonance frequency.

 Achieving transfer of maximum efficiency more than 50% at resonance frequency. planning a board: ◦ Understanding each component use and ability ◦ placing each component’s inputs and outputs on the board

Charger’s model The designed model as electrical lumped circuit

D1 D2 z Primary Secondary I1I1 I 2(t) H Eff % D2 = D1 D2 = D1/10  I 1 (t) z/D1

Oscillator DriverLC Galileo LC Diode Bridge Load

 Location: TX unit  Freq. range MHz Resistors ratio: Frequency calc.:

 Location: TX unit  Its purpose is to amplify the voltage signal without drawing current from the source

TX coil RX component RX coil TX component

 Location: TX and RX unit  Coil:  Made of Teflon  Wire – 0.3 cm  Number of loops – 8  Diameter – 11 cm  Inductance of 4.2 uH  Capacitor:  1 nF

Voltage definition in z Ratio between reflected and transferred voltage amplitude at the load Reflection coefficient with respect to z

S11 parameter האימפדנס בעל חלק מדומה חיובי מקסימלי עבור 2.09 MHz וערכו 4.8 uH

כאן חיברנו קבל בטור לסליל. האימפדנס בעל חלק ממשי טהור בקירוב מתקבל עבור 2.7 MHz S11 parameter Resonance frequency

כאן חיברנו קבל בטור לסליל. האימפדנס בעל חלק ממשי טהור בקירוב מתקבל עבור 2.2 MHz S22 parameter Resonance frequency

S21 – power delivery between the coils הגל העובר לסליל השני מקבל מקסימום ב -2.7 MHz וערכו -0.6 dB

 Location: RX unit  Consists a four-Diode bridge  Input: ac signal from the RX coil  Output: Positive voltage signal

 Location: RX unit  The load is 50 ohm  Capacitor of 10 nF is parallel connected

Set initial frequency on 1.5 MHz Measure voltage on the RX load, save it. Increase freq. by 200 KHz (voltage by Measure voltage on the RX load, save it. Compare to previous value updown Current voltage is bigger Current voltage is smaller or equal Decrease freq. by 200 KHz and stop the loop

2.4 MHz 2.6 MHz max

2.8 MHz 3 MHz

2.1MHz 2.3MHz Rectifier output is highest for frequency =2.5MHz

2.5MHz Rectifier output is highest for frequency =2.5MHz max

 We succeeded to build wireless power system with resonance frequency at 2.7 MHz  We built a flow system to calibrate the power source to work in optimal frequency  The efficiency of the system is higher than 90% in the resonance frequency