egan FETs Enable Low Power High Frequency Wireless Energy Converters M. A. de Rooij & J. T. Strydom Efficient Power Conversion

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1 The egan FET Journey Continues egan FETs Enable Low Power High Frequency Wireless Energy Converters M. A. de Rooij & J. T. Strydom Efficient Power Conversion 1 EPC - The Leader in egan FETs March, 2013 March,

2 Wireless Power 2

3 Equivalent Circuit model for the Coils L rp Ideal Transformer L rs L mp L ms 3

4 Highly Resonant Wireless System* Overview Comprises 4 main sections: 1. An amplifier (a.k.a. a power converter). 2. A transmit coil including matching network. 3. A receive coil including matching network. 4. A rectifier with high frequency filtering * Reference: Highly resonant wireless power transfer is the subject of many WiTricity US and foreign patents. Please refer to for a partial listing of WiTricity patents. 4

5 Block Diagram of the Wireless System PSU Source Unit Un-Regulated DC output 24V DC + Gate Driver PSU Gate Driver Matching Impedance Network Resonant Source Capture Device Matching Impedance Network Device Unit Feedback and Basic Control WiTricity Coils Load 5

6 Experimental System Setup Coil Feedback egan FETs RF connection Device Coil Device Board 25mm 50mm Source Board Source Coil RF connection 6

7 Control Supply Source Board of the Wireless System egan FET Circuit egan FET Heat-Sink egan Coil Voltage Feedback Coil Connection MOSFET Ext. Osc. MOSFET Circuit Main Supply MOSFET Heat-Sink 7

8 Capture Board of the Wireless System Kelvin Output Voltage Kelvin Shunt Voltage * Ammeter connection Coil Connection Output * Remove Shunt before using Ammeter 8

9 Typical Operating Waveforms 22 V input, MHz, 23.6 Ω load (15 W) Device Coil Output Switch- Node 0 Source Coil Input Current Lower Gate 0 9

10 Efficiency as function of Load Power Efficiency [%] MHz, 23.6 Ω load V in =8V V out =6.8V V in =22V V out =18.3V Output Power [W] 10

11 Thermal Performance of the Wireless System 28ºC ambient, No forced air cooling, 20 V input, MHz, 23.6 Ω load (12.5 W) 11

12 Loss Breakdown Considerations FET: Conduction Switching Gate Rectifier: Conduction losses Capacitive losses Coil: Conduction losses (skin and proximity effects) 12

Power [W] 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Loss Breakdown of the Wireless System Power Loss Break Down 22 V supply, 15 W load FET Cond. FET SW. Gate Driver Pri.

13 Power [W] Loss Breakdown of the Wireless System Power Loss Break Down 22 V supply, 15 W load FET Cond. FET SW. Gate Driver Pri. Coil Sec. Coil Rect. Cond. Rect. Cap. 0.0 Efficiency: egan FET MOSFET Ind. Coil Rectifier egan FET System 82.9% 78.8% 87.3% 93.6% 70.4% MOSFET System 66.1% 13

High Efficiency Class-E Wireless Power using egan FETs Tight coupling between source and receive coils Used EPC1010 Reported 26.8 W output at 93.

14 High Efficiency Class-E Wireless Power using egan FETs Tight coupling between source and receive coils Used EPC1010 Reported 26.8 W output at 93.6% Drain efficiency + L 1 V DD Z s/p1 R RFload egan FET C 2 L 2 Q RF C 1 A 25.6 W MHz Wireless Power Transfer System with a 94% Efficiency GaN Class-E Power Amplifier W. Chen, R. A. Chinga, S. Yoshida, J. Lin, C. Chen, W. Lo IEEE International Microwave Symposium Digest (MTT) Conference, June 2012 Page(s):

2A rms into 3 turn RF coil 87% Drain efficiency at 123.

Supply C SupplyACblock + L SuppluACblock1 C outdcblock1 Q

DS_QRF2 C outdcblock2 L SuppluACblock2 Enhancement Mode GaN

15 2A rms into 3 turn RF coil 87% Drain efficiency at MHz P out = 18 W Current-Mode Class-D egan FET RF Source V Supply C SupplyACblock + L SuppluACblock1 C outdcblock1 Q RF1 R RFload EPC2012x2 Q RF2 L outmatch V DS_QRF1 I RFload V DS_QRF2 C outdcblock2 L SuppluACblock2 Enhancement Mode GaN (egan) FETs for On-Coil MRI Transmit Amplifiers, M. Twieg, M. J. Riffe, N. Gudino, M. A. Griswold, International Society for Magnetic Resonance in Medicine 21 st Annual Meeting, April

16 Conclusions High Frequency (> 6.78 MHz) Class-D/CMD/E Wireless Energy Transfer System enabled using egan FETs. Low Losses Small Size Support circuitry available (Texas Instruments LM5113/4 gate drivers) 16

17 The end of the road for silicon.. is the beginning of the egan FET journey! EPC - The Leader in egan FETs March, 2013 March,

Efficient Power Conversion Corporation

The egan FET Journey Continues Wireless Energy Transfer Technology Drivers Michael de Rooij Efficient Power Conversion Corporation EPC - The Leader in egan FETs ECTC 2014 www.epc-co.com 1 Agenda Overview