Inter national J our nal of P o wer Electr onics and Dri v e System (IJPEDS) V ol. 11, No. 3, September 2020, pp. 1441 1448 ISSN: 2088-8694, DOI: 10.11591/ijpeds.v11.i3.pp1441-1448 r 1441 W ir eless po wer and data transfer thr ough carbon composite using a common inducti v e link T uan Anh V u 1 , Chi V an Pham 2 , W illiam T ran 3 , Anh-V u Pham 4 , Christopher S. Gardner 5 1,2,3,4 Department of Electrical and Computer Engineering, Uni v ersity of California, United State 5 La wrence Li v ermore National Laboratory , United State 1 VNU Uni v ersity of Engineering and T echnology , V ietnam Article Inf o Article history: Recei v ed Apr 21, 2019 Re vised Mar 21, 2020 Accepted May 6, 2020 K eyw ords: Ener gy harv esting Inducti v e coupling Through carbon composite W ireless data transfer W ireless po wer transfer ABSTRA CT This paper presents the design and de v elopment of an inte grated wireless po wer transfer and data communication system. The po wer and data transfer share a common inducti v e link that consists of tw o identical Helical coils placed on both sides of a carbon composite barrier . Po wer and data are transferred simultaneously through a 5-mm thick carbon composite barrier without an y ph ysical penetration or contact. Po wer transfer measurements sho w that the system can deli v er 9.7 A C po wer to the recei ving coil wi th a po wer transfer ef ficienc y of 36% through the carbon composite barrier . The system achie v es a bidirectional half-duple x data communication with the data rate of unit 1.2kbit/s. This is an open access article under the CC BY -SA license . Corresponding A uthor: T uan Anh V u, VNU Uni v ersity of Engineering and T echnology , 144 Xuan Thuy Rd., Cau Giay Dist., Hanoi, V ietnam. Email: tanhvu@vnu.edu.vn 1. INTR ODUCTION Design and optimization of wireless po wer transfe r (WPT) systems ha v e been well studied o v er t he last decades to char ge cell phones and electric v ehicles as well as to po wer up sensors o v er a short distance [1–6]. In recent years, there has been a great demand for wirelessly po wered s ensors to support structural health monitoring (SHM) for industrial applications containing carbon composite barriers and enclosures (e.g., na v al v essel, ai rcraft and chemical v at). Drilling holes for feeding wires reduces the inte grity of the structure. Specifically , practical issues include higher p r ob a bilities for the leakage of toxic chemicals and the loss of pressure or v acuum. The SHM systems typically require embedded sensors for data acquisition inside a sealed container , wireless communication, and ener gy harv esting. The sensors need to be po wered and controlled wirelessly through a barrier without an y ph ysical penetration through mechanical structures. Se v eral methods ha v e been proposed to transfer po wer and data wirelessly using a common i nducti v e link. The concept of inducti v e po wer transfer (IPT) is similar to the principle of transformers in which an alternating magnetic field in the primary coil induces a load v oltage on the secondary coil when the tw o coils are tightly coupled [7-9]. In lo w-po wer applicati ons, the inducti v e link for po wer transfer is also used for data transmission, where the data is directly modulated on the po wer carrier [10-14]. Ho we v er , these techniques ha v e lo w data rates and lo w po wer transfers. Se v eral methods using multiple inducti v e links with multiple carriers ha v e been proposed to increas e the data rate while maintaining the po wer transfer ef ficienc y [15, 16]. In these methods, po wer and data are transferred via independent ph ysical channels, where the po wer signal is deli v ered through one inducti v e J ournal homepage: http://ijpeds.iaescor e .com Evaluation Warning : The document was created with Spire.PDF for Python.
1442 r ISSN: 2088-8694 link and the data signal is transmitted through another . Ho we v er , mult iple links will cause e xt ra magnetic interferences between the tw o channels, thereby decreasing the signal-to-noise ratio (SNR) in a communication channel. Multiple inducti v e links also lead to lar ger de vice size, which is undesirable for confined space applications. The method with multiple carriers in a single inducti v e link is another candidate for WPT systems. Con v entional s ystems feed both po wer and data signals through tw o terminals of the inducti v e coil [17, 18] or use strong couple inductors t o mix them before dri ving those signals to the coil [19]. Ho we v er , these approaches cause direct interference of high po wer leakage into the data communication band at multiple harmonics. As a result, sharp-response filtering circuits or high po wer data transmission (well abo v e harmonics le v els) is required for a successful data communication. The main challenge of this approach is to achie v e a reliable communication link in the presence of a strong interference from the po wer link. In this paper , a no v el system for simultaneous po wer and data transfer through a 5-mm thick carbon composite barrier using a common inducti v e link will be presented [20, 21]. The block diagram of the proposed system is sho wn in Figure 1. In this system, po wer is applied tw o terminals of the transmitting coil while the data is fed through the coil’ s center tap. By doing this, the po wer and data signals are isolated by means of the half-coil impedance. This feeding configuration can help to reduce the data signal po wer being transmitted to only 1.5. Consequently , it significantly releases the amount of po wer that needs to be harv ested on the sensing side for sensing and communication operation. A complete system prototype is b uilt to demonst rate that it can deli v er 9.7 A C po wer to the sensing side and achie v e wireless communication at the data rate of 1.2. 2. SYSTEM O VER VIEW As demonstrated in Fi gure 1, the system is di vided into tw o parts: the primary side and the sensing side. On the primary side, a po wer amplifier (P A) deli v ers po wer to tw o terminals of the transmitting coil while the data is applied via the coil’ s center tap. The po wer and data mix ed signals are captured across tw o terminals of the recei ving coils. A rectifier is emplo yed on the sensing side to con v ert the harv ested ener gy into DC po wer . This DC po wer is then used for sensing and communication operat ion on the sensing side, which does not ha v e an y batteries. The frequenc y of the po wer carrier is set at 300 while the data carrier is set at 8. The data-carrier frequenc y should be at least an order of magnitude higher than the po wer -carrier frequenc y so that the crosstalk interference of data communication from po wer transfer is suppressed. This f acilitates the design of demodulation circuit and guara ntees the reliability of communication. Lo w frequenc y w as chosen for the wireless po wer transfer to isolate high po wer leakage at multiple harmonics into the data communication band. Con v e rsely , for the wireless data transfer , high frequenc y had to be chosen to ha v e lar ge b a nd wi dth for high data rate. Ho we v er , the frequenc y of data carrier cannot be too high because data signals may e xperience significant loss through the inducti v e link. Figure 1. Proposed system for po wer and data transfer through carbon composite Int J Po w Elec & Dri Syst, V ol. 11, No. 3, September 2020 : 1441 1448 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Po w Elec & Dri Syst ISSN: 2088-8694 r 1443 2.1. ASK transcei v er In the proposed system, bidirectional half-duple x communication between the primary side and the sensing side is implemented using amplitude-shift k e ying ( ASK) modulation. The proposed ASK transcei v er sho wn in Figure 2, is adopted in both sides. In forw ard communication, the primary side is set to a transmitter mode while the sensing side is set to a recei v er mode. In backw ard communication, the primary side is set to a recei v er mode while the sensing side is set to a transmitter mode. The ASK transcei v er can operate in tw o modes: transmitter mode and recei v er mode, which are controlled by a bidirectional electroni cs switch TPS2080 from T e xas Instruments. On the transmitter mode, digital data from an Arduino microcontroller (uC) is mix ed with an 8-kHz carrier frequenc y generated by a local oscillator (LO) on a printed circuit board (PCB). The ASK modulated signal is then amplified by a commercial audio P A TD A7391 from STMicroelectronics and emplo yed as a signal source to transmit data. On the recei v er mode, the incoming data is demodulated and read by the same Arduino microcontroller . The ASK demodulator includes an acti v e high-pass filter (HPF), a squarer , a lo w-pass filter (LPF) and a comparator . The acti v e HPF consists of a second-order RC HPF follo wed by an op-amp amplifier . The strong po wer carrier signal and its harmonics that may interfere with the baseband data signal are suppressed by 40 by the acti v e HPF . The filtered signals are then amplified and demodulated by the follo wing sub-blocks in the recei v er chain. Figure 2. Proposed ASK transcei v er , (a) ASK modulator , (b) ASK demodulator 2.2. Class-E po wer amplifier A class-E P A is co-designed with the inducti v e link for po wer transfer . Class-E P As achie v e s ignif- icantly higher ef ficienc y than their con v entional class-B or -C counterparts. The ef ficienc y is maximized by minimizing po wer dissipation, while still maintaining a desired output po wer . The insulated-g ate bipolar tran- sistor (IGBT) STGW15S120DF3 from STMicroelec tronics w as used as the po wer transistor . This IGBT f amily has been specifically optimized for lo w switching frequencies. The complete circuit of the 300 class-E P A with all component v alues are gi v en in Figure 3. The P A design is obtained by the Sokal-Raab approach [22, 23] is the coupling capacitor at the input of the P A. R 1 and R 2 form a v oltage di vider for g ate biasing. The DC-feed chok e, L 0 pro vides the connection to the DC po wer supply . L 1 and L 2 represent the coil inductances. In this design, the IGBT operates as an on/of f switch and the load netw ork shapes the v oltage and current w a v eforms to pre v ent simultaneous high v oltage and high current in the transistor . The load netw ork is designed consider - ing ef fects of the inducti v e link. The inductances of the transmitting and recei ving coils become a part of the load netw ork. C 1 and C 2 ensure that the collector v oltage and collector current switching transitions are time- displaced from each other . Consequently , the po wer dissipation is minimized, especially during the switching transitions. L 2 and C 3 form a series-parallel resonant circuit. The IGBT is dri v en with a g ate v oltage of 8 and a supply v oltage of 15. Measurement results sho w that the designed P A achie v es a high collector ef ficienc y of 54.2% when deli v ers 27 po wer at 300 to the transmitting coil. W ir eless power and data tr ansfer thr ough carbon composite ... (T uan Anh V u) Evaluation Warning : The document was created with Spire.PDF for Python.
1444 r ISSN: 2088-8694 Figure 3. Schematic diagram of the class-E po wer amplifier 2.3. P o wer management The po wer management module consis ts of an impedance transformer follo wed by se v eral v oltage re gulators. Since the impedance of the coil is approximately 1 at 300, the A C po wer is harv ested on the recei ving coil in form of lo w v oltage and hi gh current. The series-L parallel-C impedance transformer is used to boost up the harv ested A C v oltage. The A C v oltage is then con v erted into the DC v oltage by a full-bridge rectifier GBPC3502W from ON Semiconductor follo wed by se v eral smoothing capacitors. The DC v oltage is distrib uted to se v eral v oltage re gulators to generate stable v oltage supplies for po wering dif ferent sub-blocks of the ASK transcei v er and sensors on the sensing side. 2.4. Helical coil The po wer and data carrier share a common inducti v e link using a pair of identical Helical coils whose inductances are 0.45. Analysis and design of Helical coil were presented in [24-27] By co-axially align- ing a pair of coils, the wireless IPT channel is formed without an y ph ysical penetration through the carbon composite barrier . The Helical circular geometry results in a more uniform magnetic field distrib ution that sig- nificantly impro v es the ef ficienc y of ener gy transfer compared to that of the con v entional Solenoid counterpart. The Helical coils are constructed using American W ire Gauge (A WG) 16 magnet wire. The y ha v e 63 turns with inner and outer radius of 22 and 108, respecti v ely . Measurement results demonstrate that the po wer transfer ef ficienc y is 36% for transfering po wer at 300 through the 5-mm thick carbon composite barrier . 3. EXPERIMENT AL RESUL TS A complete prototype w as b uilt to demonstrate the ef fecti v eness of the proposed system. Figure 4 illustrates the measurement setup for po wer and data transfer through a 400 400 5 carbon com- posite barrier . The other Helical coil cannot be seen in the figure since it is co v ered by the carbon composite barrier . F or the practical d e monstration of the proposed system, the prototype performances were v erified in tw o e xperiments as sho wn in Figure 5. The first e xperiment v erifies backw ard communication in which the sensing side sends data to the primary side. A temperature sensor TMP36 connected to the Arduino microcon- troller on the sensing side continuously collects information on the temperature of the surrounding en vironment. The Arduino microcontroller is programmed to read this data a n d then the ASK transcei v er sends the data to the primary side at a rate of 1.2. The temperature v alues are displayed on the monitor of a computer connected to the Arduino microcontroller board for further v erification. In the second e xperiment, bidirectional half-duple x data communication is established when tw o ASK transcei v ers e xchange one thousand bytes of data. The data is enclosed by the user -defined start and stop bytes. The ASK transcei v er on the sensing side starts the communication at a data rate of 1.2 by sending the start byte follo wed by one thousand bytes of data and then the stop byte. After sending the stop byte, the transcei v er is switched to recei v er mode. On the primary side, as soon as the ASK transcei v er d e tects the start byte, it is switched to t he recei v er mode and starts recei ving the data in the backw ard communicati on. Alternati v ely , whene v er the ASK transcei v er on the primary side detects the stop byte, it is switched to the transmitter mode and starts sending the data in the forw ard communication. F or both e xperiments , the ASK transcei v er on the sensi ng side w as po wered by the rectified A C po wer that w as harv ested simultaneously while the data w as recei v ed properly without an y bit error . Int J Po w Elec & Dri Syst, V ol. 11, No. 3, September 2020 : 1441 1448 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Po w Elec & Dri Syst ISSN: 2088-8694 r 1445 Figure 4. Measurement setup Figure 5. Experiment setups: (a) Real-time measurement of en vironment temperature; (b) Bidirectional half-duple x data communication. Figure 6 (a) sho ws a typical spectrum of mea sured po wer a nd data m ix ed signals in the frequenc y domain captured by a v ector signal analyzer . As seen in this figure, the modulated data signals e xhibit lo wer side band (LSB) and upper side band (USB) symmetrically at the data-carrier frequenc y of 8. At this data rate, the channel bandwidth needed for data communication is 2.4. The po wer of the data signal at the carrier frequenc y and LSB/USB are 14.6 and 6.1, respecti v ely . At the fundamental frequenc y of 300, the po wer of transmitted signal is 30.3 while the second and third harmonics are 22.6 and 11.2, respecti v ely . Although the po wer signal is much higher than the data signal, the y are still separated when the data-carrier frequenc y is chosen to be much higher than the po wer -carrier frequenc y . Consequently , the modulated signal is not interfered with the high-order harmonics of the po wer -carrier signal. Figure 6 (b) sho ws t he mix ed signals in the time domain captured by an oscilloscope. The lo w frequenc y corresponds to the po wer -carrier signal of 300, which is used to transfer po wer to t he sensing side. The high frequenc y signal corresponds to the data-carrier signal of 8, which is used for ASK modulation. Figure 7 sho ws a measured signal w a v eforms in backw ard communication at a data rate of 1.2. The backw ard communication is more challenging due to the limited po wer b udget that can be harv ested on the sensing side. The demodulation of the weak reception data signals on the primary side is critical to ha v e data recei v ed properly . Figure 7 ( a) and 7 (b) sho w the transmitted digital data from the Arduino microcontroller and the ASK modulated signal after the data signal is mix ed with the 8-kHz carrier frequenc y generated by the local oscillator , respecti v ely . The strong po wer -carrie r signal at 300 and its harmonics are suppressed by the acti v e HPF; thus, only data signals are a v ailable for demodulation. Figure 7c plots the baseband signals after do wncon v ersion and lo w-pass filtering. Depending on the recei v ed signal strength, the reference v oltage of the follo wing comparat or is s et accordingly . The digital data coming out from the ASK demodulat or is pl otted in Figure 7 (d). Comparing Figure 7 (a) with Figura 7 (d), it is demonstrated that the transmitted and recei v ed data are e xactly the same with 0.24 delay time in transmission. The rece i v ed digital data is read by the Arduino microcontroller on the primary s ide and displayed on a computer monitor for v erificat ion. The signal-to-noise W ir eless power and data tr ansfer thr ough carbon composite ... (T uan Anh V u) Evaluation Warning : The document was created with Spire.PDF for Python.
1446 r ISSN: 2088-8694 ratio (SNR) of approximately 18 for a bandwidth of 2.4 could be obtained. Using the proposed system, sensors and communicat ion circuits enclosed in sealed containers can be po wered up and communicate with e xterior de vices without an y ph ysical penetration for wire feed-throughs. Figure 6. Measured transmitting mix ed signals in, (a) frequenc y domain and (b) time domain Figure 7. Measured signal w a v eforms in backw ard communication at data rate of 1.2, (a) T ransmitted digital data, (b) ASK modulated signals before po wer amplification, (c) Recei v ed signal after lo w-pass filtering and (d) Recei v ed digital data after thresholding 4. CONCLUSION In this paper , we ha v e presented a no v el system using multiple carriers in a single inducti v e link for wireless po wer and data transfer through the 5-mm thick carbon composite barrier . The proposed system e xploits the center tap architecture enabling high po wer transfer and data communication at the same time. Measurement results demonstrate that the system could achie v e wireless communicati on at a data rate of 1.2 while the sensing side w as po wered up using 9.7 A C po wer that w as harv ested simultaneously . Int J Po w Elec & Dri Syst, V ol. 11, No. 3, September 2020 : 1441 1448 Evaluation Warning : The document was created with Spire.PDF for Python.
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