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, 2013 www.epc-co.com
Wireless Power 2
Equivalent Circuit model for the Coils L rp Ideal Transformer L rs L mp L ms 3
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 http://www.witricity.com/pages/intellectual-property.html for a partial listing of WiTricity patents. 4
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
Experimental System Setup Coil Feedback egan FETs RF connection Device Coil Device Board 25mm 50mm Source Board Source Coil RF connection 6
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
Capture Board of the Wireless System Kelvin Output Voltage Kelvin Shunt Voltage * Ammeter connection Coil Connection Output * Remove Shunt before using Ammeter 8
Typical Operating Waveforms 22 V input, 6.639 MHz, 23.6 Ω load (15 W) Device Coil Output Switch- Node 0 Source Coil Input Current Lower Gate 0 9
Efficiency as function of Load Power Efficiency [%] 6.639 MHz, 23.6 Ω load 72 70 68 66 64 62 60 58 56 54 V in =8V V out =6.8V V in =22V V out =18.3V 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Output Power [W] 10
Thermal Performance of the Wireless System 28ºC ambient, No forced air cooling, 20 V input, 6.639 MHz, 23.6 Ω load (12.5 W) 11
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. 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 93.6% 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 13.56 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, 17-22 June 2012 Page(s): 1-3 14
2A rms into 3 turn RF coil 87% Drain efficiency at 123.5 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 2013 15
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
The end of the road for silicon.. is the beginning of the egan FET journey! EPC - The Leader in egan FETs March, 2013 March, 2013 www.epc-co.com