wireless power transfer

1478 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 57, NO. 4, APRIL 2010

Method of Load/Fault Detection for Loosely CoupledPlanar Wireless Power Transfer System

With Power Delivery TrackingZhen Ning Low, Student Member, IEEE, Joaquin Jesus Casanova, Student Member, IEEE, Paul Hadley Maier,

Jason Allen Taylor, Raul Andres Chinga, Student Member, IEEE, and Jenshan Lin, Fellow, IEEE

Abstract—A method to determine various operating modes ofa high-efficiency inductive wireless power transfer system whichis capable of supporting more than one receiver is proposed. Thethree operating modes are no-load, safe, and fault modes. Thedetection scheme probes the transmitter circuitry periodically todetermine the operating mode. For power saving, the transmitteris powered down when there is no valid receiver placed on thetransmitting coil. If any conductive or magnetic object that canaffect the total effective inductance of the transmitting coil islocated nearby, the system will enter the fault mode and shut downthe transmitter so that it will not be damaged. The safe mode is thenominal operation mode when the power transmission efficiency ishigh with minimum power loss and zero-voltage switching opera-tion of the class-E transmitter is achieved. The determination ofthe operating mode is achieved by analyzing the transmitting coilvoltage and supply current space, requiring no communicationlink between the transmitter and receiver. The linear relationshipbetween the power delivery and the supply current can be used tocalculate the power delivered to the load(s).

Index Terms—Class E, fault detection, inductive coupling, loaddetection, power tracking, wireless power transfer.

I. INTRODUCTION

THE EMERGENCE of wireless power technologies toeliminate the “last cable” [1], ranging from long-range far-

field systems to close-proximity near-field systems, has gen-erated significant research interest. Inductive coupling is oneof the leading candidates in achieving wireless power transferat power levels up to hundreds of watts [2]–[15]. Using near-field operation at frequencies below 1 MHz significantly lowersthe probability of interference and RF safety issues since thewavelength is long and the radiation is limited. However, near-field wireless power transfer systems are sensitive to nearbyconductive or magnetic objects. Although it is possible to shieldthe transmitting coil from interferences behind or beneath it,the shield does not prevent a user from potentially damaging

Manuscript received November 27, 2008; revised August 10, 2009. Firstpublished August 28, 2009; current version published March 10, 2010. Thiswork was supported in part by WiPower Inc. and in part by the Florida HighTech Corridor Council.

Z. N. Low, J. J. Casanova, J. A. Taylor, R. A. Chinga, and J. Lin are withthe Department of Electrical and Computer Engineering, University of Florida,Gainesville, FL 32611 USA (e-mail: [email protected]).

P. H. Maier is with Current Concept DesignWorks Inc., Athol, MA 01331USA (e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TIE.2009.2030821

the system by placing objects such as a metal sheet on thetransmitting coil or simply flipping the transmitting coil over ametal table. Therefore, to ensure robust operation of the system,a method of fault mode detection must be implemented so thatthe transmitter circuitry will not be damaged.

In addition to protecting the transmitting platform frombeing damaged by conductive or magnetic objects, it is alsodesirable to reduce power consumption by turning off the trans-mitter when no valid receiving device is placed on the trans-mitting platform. Therefore, the no-load power consumption(1.44 W for the fabricated system) can be reduced significantly.Although one could use a communication link to performauthentication and handshaking, there would be a considerableincrease in cost and component count. An alternative is to detectthe system loading condition by the voltages and currents ofthe transmitter. To ensure low power consumption and cost, thevoltages and currents to be detected must be either dc or beconverted to dc so that a low-speed analog-to-digital converter(ADC) can be used to accurately extract the information andconvert to digital domain.

In Section II, we discuss the proposed detection circuiton a wireless power transfer system based on similar designrules presented in [2]. In addition, a detection flowchart to beimplemented in a low-cost low-power microcontroller unit isdiscussed. The three different modes are no-load mode, safemode, and fault mode. Finally, a detail schematic and in-depthdiscussion of the fabricated transmitter with the measurementresults is presented in Section III. To illustrate that the schemecan be applied to receivers of various sizes, receivers of twodifferent sizes are presented. The measurement results of thecoil voltage and supply current space are used to determine theoperating mode of the system. The experimental results alsoshow the linear relationship between the total power deliveredto the load and supply current, which can be used to track thepower delivery to the load(s) without any communication linkbetween the transmitter and receivers.

II. PROPOSED DETECTION SCHEME

A. Wireless Power Transfer System With Detection Circuit

Fig. 1 shows the block diagram of the proposed wirelesspower transfer system with detection circuit. The class-E trans-mitter [2] in Fig. 1 operates at 240 kHz. The components areselected based on the design rules that are similar to those

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LOW et al.: METHOD OF LOAD/FAULT DETECTION FOR PLANAR WIRELESS POWER TRANSFER SYSTEM 1479

Fig. 1. Block diagram of the proposed wireless power transfer system with detection circuit (detecting the supply current and coil voltage).

TABLE ICOMPONENT VALUES

presented in [2] and will not be discussed in this paper. Thecomponent values of the system are shown in Table I.

There are three parameters that can be extracted from thewireless power transfer system, namely, the coil voltage, thesupply current, and the coil current.

The coil voltage is extracted by rectifying the coil voltagevia a high-impedance path using a half-wave rectifier. Rvcoil

and Cvcoil shown in Fig. 1 are used to smooth out the rectifiedvoltage and regulate the current flow in the rectifying diodeto prevent sudden current spikes. The voltage is then steppeddown via a potential divider using Rdivider1 and Rdivider2 toa workable voltage. To mitigate the loading effects and reducehigh-frequency noise, a buffer using a low-speed operationalamplifier, e.g., LM324, in the voltage follower configurationcan be used before the microcontroller’s ADC port.

The supply current is extracted from the circuit via thecurrent sense resistor Rsense in Fig. 1. The Rsense resistor islocated at the class-E transmitter ground before returning to the

Fig. 2. Schematic of the coil current extraction network using a current senseresistor.

system ground, instead of being located at the high side beforeLDC. Therefore, any voltage drop across the resistor will bereferenced to the system ground instead of the supply voltage.Since the voltage drop will be extremely small (0.1 V or less), anoninverting amplifier using an operational amplifier LM324can be used to amplify the voltage, mitigating any loadingeffects and reducing high-frequency noise.

Measurements of the coil current can be realized by usingeither current sense transformers or current sense resistors.Current-sensing transformers are typically large in size andoperate at frequencies that are lower than 100 kHz, makingthem impractical for this system. A current sense resistor canbe added to the low side of the coil to measure the voltagedrop across the resistor. This is more practical than placingthe current sense resistor on the high side as shown in Fig. 2for which extremely high tolerance resistors are needed for thepotential dividers. However, detecting a high-frequency ac onthe low side is challenging because it is very close to the noisyground of such a high-voltage/current system. Unlike measur-ing the supply current, which does not require rectification,both the high-frequency voltage signal and the ground noisewill be rectified. Therefore, it is not possible to perform low-pass filtering to mitigate the effects of ground noise using alow-speed operational amplifier, making it tricky to performthe precise and stable measurement of the coil current. Forthe aforementioned reasons, only the coil voltage and supplycurrent will be extracted.


Fig. 3. Detection scheme flowchart for the proposed system.

A dc switch shown in Fig. 1 before the choke inductor LDC

is used to turn off the transmitter under no-load mode or faultmode which includes an overcurrent. Additional overcurrentprotection can be implemented by using a polymeric positivetemperature coefficient (PPTC) device at the supply as a secondlevel protection. Reverse-polarity voltage protection can also beimplemented by adding a reverse-biased diode in shunt with thesupply voltage. If a reverse voltage is applied, the diode willcause a short circuit, and the PPTC will be activated to discon-nect the supply path. Overvoltage protection of sudden spikingcan be implemented by using a transient voltage suppression(TVS) diode commonly referred to as a transorb across thesupply. To prevent thermal runaway, a thermistor can be locatednext to the transistor of the power stage. By using the thermistoras part of a potential divider on which the supply voltage isapplied, the temperature can be tracked by reading the voltageacross the thermistor using the microcontroller’s ADC.

B. Detection Flowchart

The detection scheme flowchart is shown in Fig. 3. It can beimplemented using a low-cost microcontroller, such as 16F688by Microchip. It is found experimentally that the systemreaches a steady state after it is being powered on for 500 µSwhen a decision to power on or off the transmitter can be made.

The no-load and safe modes follow a similar logic flow.The only difference is that the transmitter is powered down ifno-load mode is detected, whereas the transmitter is poweredup if the safe mode is detected. Both modes will probe thecircuit for the supply current and coil voltage after each pre-determined X s to determine its operating mode (a reasonablenumber for X is 1). Increasing X will incur higher latency tomake the system response slow, and decreasing X will incurhigher no-load power consumption. The operating modes aredetermined by the supply voltage and coil voltage space, whichwill be discussed in Section III. The thresholds are dependenton the supply voltage, the transmitter’s component values,and the transmitting coil parameters. The dependence of theparameters on the receiver is found to be weak. Therefore, thethresholds work independent of the receivers as well. Hysteresisneeds to be implemented in the code so that the system does notoscillate when its operating mode is at the borderline case. Thefault counter Z is reset if the system ends up in either mode.

When the coil voltage and supply current are excessive, thesystem enters its fault mode. A common cause of fault modeis when a huge piece of metal is placed over the transmittingcoil, which significantly decreases the total effective inductanceof the transmitting coil. When this happens, the class-E zero-voltage switching (ZVS) operation is no longer valid. If thetransmitter is not powered down immediately, the transistor willbe damaged due to excessive power dissipating as heat. Thedelay to probe the system to determine if the cause of the faulthas to be rectified is increased by a factor A until it reaches N .Once the number of tries reaches N , the system will enter intothe fatal fault mode, and the only way to exit from the modeis to perform a hard reset which involves disconnecting the dcsupply of the system.

Other fault modes which are not covered by the flowchartinclude thermal runaway mode due to excessive heating at thepower stage and battery fault mode for a one-to-one system.As will be shown in Section III, it is possible to track thecharge/power received status of a receiving unit for a one-to-one power system. If the trend of the power delivered overtime deviates from the expected trend, the system will entera battery/receiver fault mode which also requires a hard reset.This also prevents possible damage when a user places anoncompliant receiver of a different charging profile on thetransmitter. Brownout and overvoltage at the supply can alsobe detected by a supply voltage monitoring network so thatthe transmitter can be powered down under fault mode. Asupply monitoring network is simply a potential divider to dropthe supply voltage to the range of the microcontroller’s ADCso that the microcontroller can make a decision based on theADC’s input.

III. EXPERIMENTAL VERIFICATION

A. System Fabrication

The wireless power transfer system is fabricated based on thecomponent values in Section II. The transmitting coil used issimilar to the one used in [14]. To ensure that the proposed de-tection scheme can be applied to the same transmitter platform


Fig. 4. Photograph of the fabricated transmitter circuit with control circuit.

regardless of the receiving coil size, two different sizes wereused in the experimental verification. For ease of integrationinto portable devices, both receiving coils are flat air core coilswith their windings tightly wounded on the perimeter to achievea maximum cross-sectional area. Depending on the devices,shielding might be required. Additional shielding will not affectthe detection scheme as it can be considered as an integralpart of the inductance matrix during the analysis. All coilswere fabricated using 100/40 round served Litz wires. A full-wave rectifier and a charge-holding capacitor after the rectifierare used to convert the ac power into dc power. The voltageregulator on the receiver is considered as part of the load so thatthe system designer is able to customize the receiver to theirrespective applications. The supply voltage for the system isselected to be 12 V. The fabricated transmitter shown in Fig. 4has a size of 15 cm × 2 cm. It is designed to be long and narrowso that it can be placed beside the transmitting coil as a singleintegrated unit. The low-power detection and control block islocated away from the high-voltage power stage to reduce noiseand coupling effects. The power input jack is located betweenthe two blocks for the same reasons.

Fig. 5 shows the schematic of the fabricated transmitter.It is split into three different blocks, namely, power stage[Fig. 5(a)], driver stage [Fig. 5(b)], and detection and con-trol stage [Fig. 5(c)]. The transmitter has two levels of pro-tection, namely, hardware protection and software controlledprotection.

Hardware protection is used as a last resort protection forwhich the thresholds are set at the maximum. It should onlybe triggered when the microcontroller (U3) in Fig. 5(c) fails.Overcurrent protection is realized by a PPTC fuse, F1 as shownin Fig. 5(a) which has a 1.5-A hold and a 3.0-A trip. TheTVS diode, D1 in Fig. 5(a), serves two purposes. It helps toeliminate any transient voltage spikes due to discharge from theenergized coil during powering down, protecting the transmitterfrom overvoltage. In addition, if the user accidentally connectsthe dc supply in reverse polarity, it will attempt to short out thesupply loading excessive current. The fuse F1 will be activatedto break the connection, protecting the transmitter circuit fromreverse voltage.

An intermediate stage of overcurrent protection is added tothe transmitter via disabling the pulsewidth modulation clock,U2 in Fig. 5(b). This is achieved by pulling the CS pin to high.The values of R15 and R16 in Fig. 5(c) are selected to shutdown the clock when the supply current exceeds 1.2 A whichis higher than the software-determined maximum current of0.85 A as shown in Fig. 10.

The transmitter should rely on the software control protectionfor its nominal operation. This is achieved by turning on andoff the PMOS transistor Q2 via a low-voltage control generated

by the microcontroller (U3) using an NMOS transistor to pulldown the gate voltage of Q2 via R1 and R2. It is importantthat the regulator for the detection and control stage U1 isplaced before the Q2 transistor so that the detection and controlstage is still in operation even when power is being cut to thedriver stage. Using a quad operational amplifier LMV324IDRas shown in Fig. 5(c), the microcontroller (U3) is able toread in four different parameters of the system. They are thecoil voltage (U4A), supply voltage (U4B), driver temperature(U4C), and driver stage current (U4D).

The coil voltage and driver stage current extraction has al-ready been discussed in Section II. The thresholds are predeter-mined by sweeping the loads as shown in Fig. 10. By extractingthe supply voltage, the transmitter is able to prevent overvoltageconditions as well as undervoltage conditions that might causethe system to deviate from its nominal operation. The system isset to a supply voltage operating range of 9–15 V. In addition,knowing the supply voltage allows the transmitter to vary itsthresholds accordingly to make it more robust. The thresholdscan be stored in the Flash memory of the microcontroller (U3).A 0.5-V resolution is sufficient to prevent any false alarm ordamage to the system. Finally, a thermistor is placed next tothe class-E driver’s transistor to monitor its temperature. Thesystem will shut down when the temperature exceeds 75 ◦C andonly resume the nominal operation when the temperature dropsbelow 60 ◦C.

B. Measurement Results on Operating Modes

The 8500 programmable dc electronic load from BK Pre-cision is used to sweep various loading conditions. It canalso be used to emulate various portable devices such as cellphones and MP3 players. Fig. 6 shows the efficiency–powerplot of a single-receiver setup using big and small receivers.The efficiencies of both receivers are similar. A better than60% efficiency can be achieved for a power delivery level thatis above 1 W. The big receiving coil has a slightly higherefficiency. Power delivery is about 6 W using the big coil andabout 5 W using the small coil.

Fig. 7 shows the coil voltage and supply current spacediagram which is used to determine the different modes. Thesystem enters the no-load mode when the operating conditionis in the vicinity of the diamond shape. At the lower coil voltage(less than 80 Vrms) and current (less than 0.8 A) is the safe zonewhen two receivers are at their nominal operation. Therefore,the safe zone is located at the bottom left corner of the coilvoltage and supply current space as any excessive voltage orcurrent will damage the transmitter. The small receiving coilgenerates a larger transmitting coil voltage because the sameamount of power delivery is required over a smaller receivingarea, which requires a stronger magnetic field. Two differentpotential fault scenarios, a large copper plate being broughtcloser to the transmitting coil and a large copper plate beingslid over the transmitting coil, are shown in Fig. 7. The soliddashed line shows the trend of the coil voltage and supplycurrent moving in clockwise when the distance between thetransmitting coil and a larger copper sheet becomes smaller.ZVS starts to fail at the voltage inflection point as more energy


Fig. 5. (a) Schematic of the power stage of the fabricated transmitter. (b) Schematic of the driver stage of the fabricated transmitter. (c) Schematic of the detectionand control stage of the fabricated transmitter.


Fig. 6. Efficiency–power plot of a single-receiver setup (Solid black line)Small coil. (Dashed gray line) Big coil.

Fig. 7. Examples of different loading conditions on coil voltage versus supplycurrent space.

is dissipated across the transistor instead of being transferredto the load (copper pate). If the system does not shut downimmediately, the transistor will be damaged due to heating. Thehollow dashed line shows an increasing coil voltage and supplycurrent when the overlapped area between the transmitting coiland a large copper plate increases. High coil voltage will leadto overvoltage problems at various points of the circuit anddamage the components.

The no-load operating point will be brought closer to thesafe zone if and only if the coupling coefficient between thetransmitting and receiving coil is reduced significantly. Unlessthe coupling coefficient is very weak (< 0.05), there will besufficient spacing in the coil voltage and supply current spacediagram for the system to easily differentiate between the no-load and safe mode. Such weak coupling is unlikely to happenas the receiving coil is intended to be placed on the transmittingcoil. Therefore, the gap between them will be small. On theother hand, some overlap might be observed between the faultand no-load mode when a sheet of metal is placed next to theedge of the transmitting coil or a very small sheet of metal isplaced on the transmitting coil. This is because the change inself-inductance of the transmitting coil due to the metal sheetis very small, thus making the loading condition similar to no

Fig. 8. Efficiency–power plot of three sets of dual-load measurements andtwo sets of single-load measurements using a combination of big and smallreceiving coils.

Fig. 9. Transmitter coil voltage and supply current space illustrating threedifferent zones: no load, single load, and dual loads.

load. Such fault condition does not damage the transmitter, and,since the transmitter will be turned off during the no-load mode,it can be considered as no-load mode.

Three sets of measurements were carried out on the systemusing two loads of load resistance ranging from 20 to 4000 Ωin 14 steps. The three sets are two big coils, two small coils,and one big coil with one small coil. The efficiency plots of thethree measurements are shown in Fig. 8. In addition, two single-receiver measurements are also shown in Fig. 8 for comparison.The dc–dc efficiency is above 70% for power delivery levelsthat are above 3 W, crossing 85% for some load points. Thespread of the efficiency is approximately ±5% regardless of thenumber of receivers. All load conditions achieved the ZVS op-eration, maintaining high-efficiency operation with minimumpower loss.

Fig. 9 shows the transmitting coil voltage and supply spacefor a single load (big coil and small coil) and dual loads.Although there is some overlapping between the two spaces,it is possible to detect the number of loads for most of theloading conditions. As shown in Fig. 9, a sharp transition isobserved when an extra load is being placed on or removedfrom the transmitting coil. Therefore, the system can easilydetect if an additional receiver is placed on the transmitting coilor being removed from it. It is possible to detect the number of


Fig. 10. Transmitter coil voltage and supply current space diagram illustratingthree different zones: no load, safe, and fault.

loads when the transmitter is powered on with valid loads onthe transmitting coil because, during the initial power-on statesof most electronic devices, they will not draw much power.Therefore, the power delivery will slowly ramp up during thefirst few seconds when the transmitter is powered on. Thesystem will observe an initial coil voltage of 40–48 Vrms fordual loads and 52–58 Vrms for single loads.

Summarizing the aforementioned discussions, Fig. 10 showsthe transmitter coil voltage and supply current space indicatingthe various zones. The no-load zone is enclosed by the redcircle, and the safe zone is enclosed by the blue lines. Thesafe zone has two steps. For a supply current that is below0.3 A, the transmitting coil voltage should be between 32 and64 Vrms, whereas, for a supply current that is above 0.3 A, thetransmitting coil voltage should be between 32 and 80 Vrms.Any supply current that is greater than 0.85 A is considered asa state of overcurrent for this system and determined as faultmode. In fact, any operating condition that is not within thesafe or no-load zone is considered to be in the fault zone. Thepurple zone on the top left corner in Fig. 10 is an invalid zonebecause the supply current is too low to generate such highvoltages and would never occur. The ZVS operation is stillvalid in the area above the safe zone. However, the transmittingcoil voltage is very high and might damage the components.In addition, excessive transmitter coil voltage might lead tothermal runaway. The brown area on the right of the safezone is when the transmitter no longer operates under the ZVScondition. When this happens, a large amount of energy isdissipated across the transistor as the high voltage across thedrain of the transistor and the high current through the transistorare no longer orthogonal in time.

C. Measurement Results on Power Delivery Tracking

An interesting linear relationship between the supply currentand the power delivered to the load is shown in Fig. 11. Theresults from the five sets of measurements can consistently bedescribed using the equation y = 0.095x + 0.055, where they-axis is the supply current to the transmitter and the x-axisis the power delivered to the load. Based on the 12-V supply

Fig. 11. Linear relationship between the supply current and the power de-livered to the loads for all five sets of measurements. (Solid dashed line)y = 0.095x + 0.055.

Fig. 12. Power delivery error distribution plot. The calculated power deliveryis based on the measured supply current. (Solid dashed line) Ideal error-freecalculation.

voltage, the transmitter requires 0.66 W (an overhead loss)plus an additional input power of 1.14 W for every additional1 W of power at the receiver. Once the system is operating inthe safe zone, using the proposed equation, Fig. 12 shows theplot of the calculated delivered power via the measured supplycurrent to the transmitter versus the actual delivered power.The results show relatively good agreement at all power levelswith an average error of −0.08 W and a standard deviation of0.16 W for 616 sets of reading.

Although the experimental verification shows the feasibilityof the proposed load/fault mode detection scheme, the thresh-olds for the different modes and the equation to track the powerdelivery are highly dependent on the supply voltage. Therefore,a voltage-sensing mechanism is required to detect the supplyvoltage and make appropriate adjustments to the thresholds. Apotential divider used to acquire the transmitting coil voltagecan be used to reduce the supply voltage to a level that the ADCof the microprocessor can acquire. In addition, the performanceof the system is also dependent on the coupling coefficientand component tolerance, particularly Crx, Lout, and Cout.To ensure robust operation, the transmitting coil must be ableto generate a substantially even field as shown in [14] andcomponents with tolerance better than 5% (2% recommended).


IV. CONCLUSION

A load detection scheme without using any communica-tion link between the transmitting platform and the receivingunit has been proposed and implemented in a wireless powertransfer system. Using the transmitter coil voltage and supplycurrent space, the system is capable of differentiating amonga safe zone for nominal operation, no-load zone for energysaving, and fault zone when invalid loads that might damagethe system are present. Power delivery to the receiver(s) canbe tracked by using the linear relationship between the powerdelivery and the supply current, which is valid for all receiverson a transmitting platform. The standard deviation of the errorcalculated using the supply current is only 0.16 W. By trackingthe power delivery, the transmitter is able to detect a faultyreceiver when the power delivery trend over time deviates fromthe expected trend.

Wireless power transfer systems using the proposed loaddetection scheme will be able to ensure robust operation evenwhen invalid loads that might damage the systems are present.The proposed scheme also enables overall energy-efficient op-eration by powering down the transmitter to reduce the powerconsumption when no valid receiver load is present.

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Zhen Ning Low (S’01) received the B.Eng. de-gree under the accelerated bachelor’s program fromNanyang Technological University, Singapore, in2005. He is currently working toward the Ph.D.degree in the Department of Electrical and ComputerEngineering, University of Florida, Gainesville.

In February 2005, he joined the Institute for In-focomm Research, Singapore, as a Research En-gineer, where he was involved in Zigbee wirelesssensor networks and ultrawideband position locationsystems. He is currently the Team Leader of the

wireless power transmission project with the Radio Frequency Circuits andSystems Research Group. His current research interests include wireless powertransmission, RF systems, microwave circuits, low-power sensor networks,and antenna design. He has authored or coauthored 16 technical publicationspublished in refereed journals and conference proceedings. He has six patentapplications in the area of wireless power transmission.

Joaquin Jesus Casanova (S’06) received the B.S.and M.S. degrees in agricultural and biological engi-neering from the University of Florida, Gainesville,in 2006 and 2007, respectively, where he is currentlyworking toward the Ph.D. degree in electrical engi-neering in the Department of Electrical and Com-puter Engineering.

His current research interests include wirelesspower transfer, heat and mass transfer, and patternrecognition. His previous research included micro-wave remote sensing of agricultural systems.

Mr. Casanova is a member of the American Society of Agricultural andBiological Engineers.

Paul Hadley Maier received the B.S. degree in elec-trical engineering and the M.B.A. degree with newproduct development concentration from WorcesterPolytechnic Institute, Worcester, MA, in 1985 and2003, respectively.

For over 20 years as an Engineer and EngineeringManager, his work has included power electronicdesign in commercial and military applications andnumerous embedded system designs. In 1985, hejoined the United Technologies Hamilton StandardDivision, where he designed power and control elec-

tronics for jet engines. From 1987 to 2000, he was with Simplex Time Recorder(now Tyco), where he focused on power supply and battery backup systemdesign for building management systems. From 2000 to 2005, he was withEMC, Inc., where he was responsible for the development of power and batterydesigns for fault-tolerant data storage systems. He is currently a Consultant andthe Co-owner of Current Concept DesignWorks Inc., Athol, MA—a design andconsulting firm specializing in embedded systems and power electronics. He isthe holder of 15 U.S. patents.


Jason Allen Taylor received the B.S. degree fromthe University of Florida, Gainesville, in 2008, wherehe is currently working toward the M.S. degree inelectrical engineering.

His current research interests include controls,machine intelligence, machine learning, and wirelesspower transmission.

Raul Andres Chinga (S’08) received the B.S. de-gree from the University of Florida, Gainesville, in2008, where he is currently working toward the Ph.D.degree in electrical engineering.

His current research interests include wireless en-ergy transmission, high-speed near-field communi-cation, and RF system-on-chip integration.

Mr. Chinga was the recipient of the Bridge to theDoctorate Fellowship from the University of Floridain May 2008.

Jenshan Lin (S’91–M’94–SM’00–F’10) receivedthe B.S. degree from National Chiao Tung Univer-sity, Hsinchu, Taiwan, in 1987, and the M.S. andPh.D. degrees in electrical engineering from the Uni-versity of California, Los Angeles, in 1991 and 1994,respectively.

In 1994, he joined AT&T Bell Labs (later LucentBell Labs), Murray Hill, NJ, as a member of Tech-nical Staff, where he became the Technical Managerof RF and High Speed Circuit Design Research in2000 and was involved with RF integrated circuits

using various technologies for wireless communications. In September 2001,he joined Agere Systems, a spin-off from Lucent Technologies. In July 2003, hejoined the University of Florida, Gainesville, as an Associate Professor, wherehe has been a Full Professor since August 2007. His current research interestsinclude sensors and biomedical applications of microwave and millimeter-wavetechnologies, wireless energy transmission, RF system-on-chip integration,and integrated antennas. He has authored or coauthored over 180 technicalpublications in refereed journals and conference proceedings. He is the holderof seven patents.

Dr. Lin is an Associate Editor for the IEEE TRANSACTIONS ON

MICROWAVE THEORY AND TECHNIQUES. He was the General Chair of the2008 RFIC Symposium and the Technical Program Chair of the 2009 Radioand Wireless Symposium. He was the recipient of the 1994 UCLA OutstandingPh.D. Award, the 1997 Eta Kappa Nu Outstanding Young Electrical EngineerHonorable Mention Award, and the 2007 N. Walter Cox Award from the IEEEMicrowave Theory and Techniques Society.