19094888
A Novel WPT System Based on Dual Transmitters and Dual Receivers for High Power Applications: Analysis, Design and Implementation
Traditional Wireless Power Transfer (WPT) systems only have one energy transmission path, which can hardly meet the power demand for high power applications, e.g., railway applications (electric trains and trams, etc.) due to the capacity constraints of power electronic devices. A novel WPT system based on dual transmitters and dual receivers is proposed in this paper to upgrade the power capacity of the WPT system. The reliability and availability of the proposed WPT system can be dramatically improved due to the four energy transmission paths. A three-dimensional finite element analysis (FEA) tool ANSYS MAXWELL (ANSYS, Canonsburg, PA, USA) is adopted to investigate the proposed magnetic coupling structure. Besides, the effects of the crossing coupling mutual inductances among the transmitters and receivers are analyzed. It shows that the same-side cross couplings will decrease the efficiency and transmitted power. Decoupling transformers are employed to mitigate the effects of the same-side cross couplings. Meanwhile, the output voltage in the secondary side can be regulated at its designed value with a fast response performance, and the system can continue work even with a faulty inverter. Finally, a scale-down experimental setup is provided to verify the proposed approach. The experimental results indicate that the proposed method could improve the transmitted power capacity, overall efficiency and reliability, simultaneously. The proposed WPT structure is a potential alternative for high power applications.
22764176
Investigation of Methods for Data Communication and Power Delivery Through Metals
When a sensor is located within a metallic housing, conveying data back to a controller or data logger is not trivial. To maintain structural integrity, or simply for ease of installation, it is often not desirable to break the wall of the vessel, preventing any hard-wired solution. The conducting nature of the structure prevents the effective use of radio communications due to skin effect. Applications involving sealed containers also have a requirement for power delivery, as the periodic changing of batteries is impractical. In this paper, a number of systems are presented for through-metal communications and power delivery. A novel noncontact electromagnetic acoustic transducer communication system is demonstrated, which is capable of data rates in excess of 1 Mb/s. Furthermore, a power transfer efficiency of approximately 4% is shown to be achievable through 20-mm-thick stainless steel using inductive coupling. These novel solutions are critically compared to previous systems based on piezoelectric transducers.
53582537
Investigation of High-Efficiency Wireless Power Transfer Criteria of Resonantly-Coupled Loops and Dipoles through Analysis of the Figure of Merit
The efficiency of a Wireless Power Transfer (WPT) system is greatly dependent on both the geometry and operating frequency of the transmitting and receiving structures. By using Coupled Mode Theory (CMT), the figure of merit is calculated for resonantly-coupled loop and dipole systems. An in-depth analysis of the figure of merit is performed with respect to the key geometric parameters of the loops and dipoles, along with the resonant frequency, in order to identify the key relationships leading to high-efficiency WPT. For systems consisting of two identical single-turn loops, it is shown that the choice of both the loop radius and resonant frequency are essential in achieving high-efficiency WPT. For the dipole geometries studied, it is shown that the choice of length is largely irrelevant and that as a result of their capacitive nature, low-MHz frequency dipoles are able to produce significantly higher figures of merit than those of the loops considered. The results of the figure of merit analysis are used to propose and subsequently compare two mid-range loop and dipole WPT systems of equal size and operating frequency, where it is shown that the dipole system is able to achieve higher efficiencies than the loop system of the distance range examined.
18035724
Three-Phase Soft-Switching Inverter With Minimum Components
In this paper, a novel three-phase soft-switching inverter is presented. The inverter-switch turn on and turn off are performed under zero-voltage switching condition. This inverter has only one auxiliary switch, which is also soft switched. Having one auxiliary switch simplifies the control circuit considerably. The proposed inverter is analyzed, and its operating modes are explained in details. The design considerations of the proposed inverter are presented. The experimental results of the prototype inverter confirm the theoretical analysis.
19852756
/spl mu/-Synthesis for Frequency Uncertainty of the ICPT System
A μ-controller is designed based on the structured singular value with regard to the frequency uncertainty of a real inductively coupled power transfer (ICPT) system. Due to system-parameter variations (such as system load) and nonlinear features of ICPT systems, the operating frequency will be perturbed accordingly. Uncertainty in the operating frequency will contribute to electromagnetic interference and power losses, and even instability of ICPT systems. To fulfill a robust stability and robust performance (RSRP) design, a generalized state-space averaging model for a nominal ICPT system is established by developing the equivalent circuit equations and expanding the related circuit variables as the Fourier series. A linear fractional transformation of this nominal model and its uncertainty is discussed to generate a standard configuration for μ-synthesis. The D-K iteration method is proposed for the “optimal” RSRP design. Computer simulation and a practical experiment are conducted to verify the RSRP of the μ-synthesis control system to ensure that the μ-synthesis algorithm is effective for ICPT systems.
110188513
An energy transmission system for an artificial heart using leakage inductance compensation of transcutaneous transformer
A power supply system using a transcutaneous transformer to power an artificial heart through intact skin has been designed and built. In order to realize both high-voltage gain and minimum circulating current, compensation of leakage inductances on both sides of a transcutaneous transformer is proposed. A frequency region which realizes the robustness against coupling coefficient and load variation is identified. In this region, the power converter has inherent advantages such as zero-voltage switching (ZVS) or zero-current switching (ZCS) of the switches, high-voltage gain, minimum circulating current and high efficiency.
21008556
A Frequency Control Method for Regulating Wireless Power to Implantable Devices
This paper presents a method to regulate the power transferred over a wireless link by adjusting the resonant operating frequency of the primary converter. A significant advantage of this method is that effective power regulation is maintained under variations in load, coupling and circuit parameters. This is particularly important when the wireless supply is used to power implanted medical devices where substantial coupling variations between internal and external systems is expected. The operating frequency is changed dynamically by altering the effective tuning capacitance through soft switched phase control. A thorough analysis of the proposed system has been undertaken, and experimental results verify its functionality.
47407502
Contactless power delivery system for mining applications
The authors present the application of a power delivery system design unifying power electronics and a coaxial-winding transformer for devices that require contactless connection and/or relative motion while delivering large amounts of power. The transformer's unique characteristics and how they might be used to advantage in combination with power electronics are emphasized. Applications which have near-term realizability are flexible power distribution, material handling, autonomous electric vehicles, and battery opportunity recharge. Test results on a scale prototype are presented to verify the concepts.<<ETX>>
23502267
Optimization of a Contactless Power Transfer System for Electric Vehicles
A contactless charging system based on a circular coil configuration is presented for electric vehicles. An analytical model of the charging system is derived and used to investigate the effect of system dimensions on the system mutual inductance. The efficiency of the system is then calculated and used as a criterion to optimize the dimensions of transmitter and receiver coils in an uncompensated system, as well as series and parallel compensated systems. As a result, several design rules are presented. Following these rules, it is shown that significant improvement in the system efficiency is achieved by optimizing the coil dimensions while the length and weight of coils are kept constant. The performances of the optimized systems are evaluated using the 3-D finite-element method (FEM) and experiments. The FEM and experimental results are in good agreement, confirming the validity of the analytical model and the optimization approach.
13031586
A Methodology for Making a Three-Coil Wireless Power Transfer System More Energy Efficient Than a Two-Coil Counterpart for Extended Transfer Distance
A new methodology for ensuring that a three-coil wireless power transfer system is more energy efficient than a two-coil counterpart is presented in this paper. The theoretical proof and the conditions for meeting the objective are derived and practically verified in a practical prototype. The key features of the magnetic design are to: 1) shift the current stress from the primary driving circuit to the relay resonator; and 2) generate a large relay current for maximizing magnetic coupling with the receiver coil for efficient power transfer. Consequently, the current rating and cost of the driving circuit can be reduced and the overall quality factor and system energy efficiency are improved. This approach utilizes the combined advantages of the maximum efficiency principle and the use of relay resonator to overcome the energy efficiency problem for applications with extended energy transfer distances.
26134005
Comparison of Position-Independent Contactless Energy Transfer Systems
This paper presents a comparison of position-independent contactless energy transfer systems by means of an inductive coupling, as a solution to overcome moving cables in emerging mechatronic applications with a linear moving load. A 2-D electromagnetic model of the contactless energy transfer system is derived and applied to six different topologies, which have either air-cored coils or a combination of salient or nonsalient magnetic cores. A parametric sweep is performed to obtain an optimal parameter set for each topology, suited for a power transfer of 1 kW with a position-independent mutual inductance between the primary and secondary coils. Comparison among the topologies shows that slotted topologies are less suited for a constant power transfer and that the geometry can be optimized for a mutual inductance variation below 3% along the linear movement.
7198007
Multiphase Pickups for Large Lateral Tolerance Contactless Power-Transfer Systems
The majority of commercial contactless power-transfer systems used in manufacturing applications can only tolerate limited movement of the power pickup relative to the track to which it is magnetically coupled. This paper describes a new multiphase (quadrature) pickup that significantly improves the tolerance of the power receiver to such relative movement, enabling expanded applications such as continuously powered automatic guided vehicles, robots, and other vehicles to be considered. The advantage gained is largely independent of the track type, so that single-phase or multiphase tracks can be used as desired to improve both the power transfer and lateral tolerance as required. The improvement is achieved by capturing both vertical and horizontal components of magnetic flux around any track.
44460060
Narrow-Width Inductive Power Transfer System for Online Electrical Vehicles
A new inductive power transfer system with a narrow rail width, a small pickup size, and a large air gap for online electric vehicles is proposed in this paper. By introducing a new core structure, the orientation of the magnetic flux alternates along with the road; hence, an inductive power transfer system with a narrow rail width of 10 cm, a large air gap of 20 cm, and a large lateral displacement about 24 cm was implemented. The resonant circuit of the inductive power transfer system, driven by a current source, was fully characterized. The experimental results showed that the maximum output power was 35 kW and that the maximum efficiency was 74% at 27 kW. The proposed system was found to be adequate for electric vehicles, allowing them to drive freely on specially implemented roads by obtaining power from the buried power supply rail.
32781325
Development of 1-MW Inductive Power Transfer System for a High-Speed Train
Design and fabrication of a 1-MW inductive power transfer (IPT) system that supplies power to the vehicle in real time without any battery charge is proposed for a high-speed train. The IPT system consists of a 1-MW resonant inverter, a 128-m transmitter, four pickups, including rectifiers, and a wireless feedback network to maintain a constant output voltage of the pickups. The operating frequency of the system is 60 kHz to achieve efficient power transfer with a large air gap. The measured efficiency of the IPT system at the 818-kW output power of the pickups for the 5-cm air gap is 82.7%. The electromagnetic field and the induced voltage at the rail are also measured for safety evaluation. The fabricated IPT system was adapted to the high-speed train, and the train successfully accelerates to a speed of 10 km/h according to startup procedures.
112316466
Cascaded Multi-Level Inverter Based IPT Systems for High Power Applications
A single phase H-bridge inverter is employed in conventional Inductive Power Transfer (IPT) systems as the primary side power supply. These systems may not be suitable for some high power applications, due to the constraints of the power electronic devices and the cost. A high-frequency cascaded multi-level inverter employed in IPT systems, which is suitable for high power applications, is presented in this paper. The Phase Shift Pulse Width Modulation (PS-PWM) method is proposed to realize power regulation and selective harmonic elimination. Explicit solutions against phase shift angle and pulse width are given according to the constraints of the selective harmonic elimination equation and the required voltage to avoid solving non-linear transcendental equations. The validity of the proposed control approach is verified by the experimental results obtained with a 2kW prototype system. This approach is expected to be useful for high power IPT applications, and the output power of each H-bridge unit is identical by the proposed approach.
47543718
A Parallel Topology for Inductive Power Transfer Power Supplies
High-power inductive power transfer (IPT) systems operate at power levels of 100 kW or more. However, existing high-power IPT power supplies are typically designed for one power level and are expensive to make, due to the use of high-power electronic components. This paper presents a parallel IPT power supply topology that can achieve high output power levels in a cost effective manner. The parallel topology can minimize uneven power sharing due to component tolerance, and does not require any additional reactive components for parallelization. In addition, it can continue to operate when a faulty parallel unit is electronically shut down, dramatically improving the availability and reliability of the systems. Furthermore, flexible output power levels may be achieved by connecting identical modules in parallel. A 6 kW parallel power supply has been constructed by connecting three 2 kW power supplies in parallel. The maximum efficiency of the power supply and track is measured to be 94%.
437459
Active and Reactive Currents Decomposition-Based Control of Angle and Magnitude of Current for a Parallel Multiinverter IPT System
In order to improve the power capacity of the resonant inverter that feeds the inductive power transfer (IPT) system for high-power applications, a parallel multiinverter IPT system is presented here to upgrade the power level of the IPT system. Besides, a quick and accurate active and reactive currents decomposition method without phase-locked loop is also proposed so that the active and reactive currents can be controlled independently. This method can minimize the circulating current caused by asymmetrical resonant components and different dc input voltages. Meanwhile, the track current can be regulated at its designed value with a fast response performance. Moreover, a protection device and a protection scheme are designed to disconnect the fault inverter unit, which can ensure that the whole system works continuously so as to improve the reliability and availability dramatically. Finally, a 3-kW experimental setup using a two-inverter IPT system is conducted to verify the performance of the proposed method. The overall efficiency of the improved IPT system is up to 93.5% at 2.87 kW output, and the experimental results also indicate that the proposed method improves the stability of track current control and achieves circulating current minimization.
206703704
Analysis and Practical Considerations in Implementing Multiple Transmitters for Wireless Power Transfer via Coupled Magnetic Resonance
Multiple transmitters can be used to simultaneously transmit power wirelessly to a single receiver via strongly coupled magnetic resonance. A simple circuit model is used to help explain the multiple-transmitter wireless power transfer system. Through this particular scheme, there is an increase in gain and “diversity” of the transmitted power according to the number of transmit coils. The effect of transmitter resonant coil coupling is also shown. Resonant frequency detuning due to nearby metallic objects is observed, and the extent of how much tuning can be done is demonstrated. A practical power line synchronization technique is proposed to synchronize all transmit coils, which reduces additional dedicated synchronization wiring or the addition of an RF front-end module to send the reference driving signal.
7966096
Effect of Coupling Between Multiple Transmitters or Multiple Receivers on Wireless Power Transfer
The operation of wireless power transfer systems with multiple transmitters (TXs) or receivers (RXs) is investigated. With multiple TXs or RXs in a limited space, couplings occur between TXs or between RXs. The frequency conditions for maximum efficiency and power transfer under such couplings are proposed. Effective resonant frequency of the TXs or the RXs is changed due to such couplings, and driving and/or resonant frequencies should therefore be adjusted accordingly. The amount and type of the required adjustments are provided. The efficiencies in these conditions are discussed. These concepts are supported by experiments with couplings between TXs or between RXs. Using the proposed frequency adjustments, 51-65-W power is transferred with 45%-57% efficiency, even with very low coupling coefficients of 0.025-0.063 from TX to RX. This improvement is significant compared to the unadjusted cases where less than 4 W is transferred with only 5%-33% efficiency.
112230434
A Novel IPT System Based on Dual Coupled Primary Tracks for High Power Applications
Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters’ output voltage with the phase shift control approach. In addition, the system’s efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.
32909538
Investigation of Near-Field Wireless Power Transfer Under Multiple Transmitters
We derive the upper bound for wireless power transfer in the near-field region under the multiple-transmitter scenario. It is found that a stable region in power transfer efficiency (PTE) can be created for sufficiently close spacing between two transmitters, in contrast to the monotonic decay of the single-transmitter case. We next demonstrate through simulation and measurement that such a bound can be approached by using efficient, electrically small, folded cylindrical helix dipoles. The measurement shows a 17% PTE value over a 0.3λ region between the two transmitters, corroborating the theory and simulation. Results from the four-transmitter case show that the stable PTE region can be extended to two-dimensional space.
32381042
Multiple Receiver Support for Magnetic Resonance Based Wireless Charging
Wireless charging is an emerging trend for mobile and portable devices with initial products appearing in the market, providing significant user convenience. Magnetic resonance based charging is a technique that provides support for charging multiple receivers with the same transmitter. However, it suffers from the issue of peak splitting due to coupling from neighboring receivers, reducing in significant power transfer loss (> 10 dB). We propose novel tuning algorithms along with communication support to eliminate the coupling loss. We provide methods for charging multiple receivers simultaneously where the tuning can be done at the transmitter only allowing simple, low complexity receiver designs such as mobile phones that do not need highly accurate tuning for magnetic resonance.
5180948
Magnetic Resonant Coupling As a Potential Means for Wireless Power Transfer to Multiple Small Receivers
Wireless power transfer via magnetic resonant coupling is experimentally demonstrated in a system with a large source coil and either one or two small receivers. Resonance between source and load coils is achieved with lumped capacitors terminating the coils. A circuit model is developed to describe the system with a single receiver, and extended to describe the system with two receivers. With parameter values chosen to obtain good fits, the circuit models yield transfer frequency responses that are in good agreement with experimental measurements over a range of frequencies that span the resonance. Resonant frequency splitting is observed experimentally and described theoretically for the multiple receiver system. In the single receiver system at resonance, more than 50% of the power that is supplied by the actual source is delivered to the load. In a multiple receiver system, a means for tracking frequency shifts and continuously retuning the lumped capacitances that terminate each receiver coil so as to maximize efficiency is a key issue for future work.
2608021
Optimization using transmitting circuit of multiple receiving antennas for wireless power transfer via magnetic resonance coupling
Electromagnetic resonance coupling technology has received more attention than other wireless power transfer technologies due to its capability to transfers energy across large air gap with high efficiency. The fundamental characteristics of a paired transmitting antenna and receiving antenna have been examined. However, in practical use, more than one receiving antenna is sometimes used, and some applications require multiple receiving antennas. In particular, this electromagnetic resonance coupling technology is desirable for powering multiple receiving antennas simultaneously because it is robust to displacement. In this paper, the multiple antennas efficiency optimization by transmitting circuit considering effect of cross-coupling and sign of mutual inductances, are proposed. The equivalent circuits for multiple antennas enable calculation of impedance matching circuit's parameters which will be used to optimize the transmitting antenna to achieve high efficiency. The equivalent circuits for multiple antennas enable to calculate high efficiency and it is optimized by changing transmitting circuit. This is also verified by electromagnetic field analysis, experiment and equivalent circuit theory. Proposed method is suitable for designing multiple antenna power supply system.
6287395
FPGA-Based Implementation of Multiple Modes in Near Field Inductive Communication Using Frequency Splitting and MIMO Configuration
Conventional near field inductive wireless power transfer theory shows that systems suffer from splitting frequency behaviors when strong coupling condition exists between the transmitter and the receiver. However, this characteristic has not been explored for communication. Our analysis demonstrates that the splitting behaviour of frequency creates multiple frequencies that support inductive communication in MIMO configuration. As a result, we implement a binary chirp modulation on an FPGA and validate two channel communication using splitting. This paper introduces the use of chirp signals to spread data and excite inductive MIMO systems. The simulation and experiment show that the splitting frequency depends on a quality factor and the flux coupling condition between the data source and receiver. In other words, the degree of mutual coupling defines the splitting mode. This paper proves that multi-channel communication using splitting can be used for data transmission. The results show that data rates of 50 Mbps or 69 Kbps can be achieved for each channel between the transmitters and receivers when the transmitter and receiver operate at the original resonant frequency of 13.56 MHz or 28 KHz, respectively and the distance between them varies from about 1 cm to 10 cm.
109513204
Modular-based inductive power transfer system for high-power applications
Although the demand for high-power inductive power transfer (IPT) systems is on the rise, implementation of such IPT systems using low-cost semiconductor devices has been a challenge. This study presents a new IPT topology that facilitates easy integration of multiple IPT modules, which are made of low cost and freely available semiconductor components, to cater for high-power applications. An intermediate circuit, comprising an inductor-capacitor-inductor resonant network, serves as a contactless interface through which the modules of primary and secondary (pick-up) systems can be either series or parallel integrated. Inductor coils of the intermediate circuit and both primary and pick-up systems are magnetically coupled to allow for contactless power transfer. The proposed topology is parallel compensated to minimise its var requirement, and both the direction and amount of power flow are controlled by phase and/or magnitude modulation of voltages generated by primary and pick-up side converters. Theoretical analysis, together with simulations and experimental evidence of integrating four prototype bi-directional IPT systems to cater for 1.8 kW demand, is presented to show that the proposed new IPT topology is suitable for high-power applications, and flexible for both bi-directional and uni-directional contactless power transfer.
109675369
A Loosely Coupled Planar Wireless Power Transfer System Supporting Multiple Receivers
A high-efficiency wireless power transfer system which is capable of supporting more than one receiver using class E operation for transmitter via inductive coupling has been designed and fabricated. The design approach of the system is also presented in this paper. The system requires no complex external control system but relies on its natural impedance response to achieve the desired power delivery profile across a wide range of load resistances while maintaining high efficiency to prevent any heating issues. A switch circuit is used to decouple the fully charged receiver from the system so that power delivery to the other receiver can be improved. The fabricated system at 12 V supply voltage is compact and capable of approximately 2.5 W of power delivery to each of the two receivers in a dual receiver setup and 5 W to a single receiver alone or when the other receiver is decoupled by the receiver switch. During high-power delivery state, the system efficiency is between 67.5% and 77.5%.
16443335
A Wireless Magnetic Resonance Energy Transfer System for Micro Implantable Medical Sensors
Based on the magnetic resonance coupling principle, in this paper a wireless energy transfer system is designed and implemented for the power supply of micro-implantable medical sensors. The entire system is composed of the in vitro part, including the energy transmitting circuit and resonant transmitter coils, and in vivo part, including the micro resonant receiver coils and signal shaping chip which includes the rectifier module and LDO voltage regulator module. Transmitter and receiver coils are wound by Litz wire, and the diameter of the receiver coils is just 1.9 cm. The energy transfer efficiency of the four-coil system is greatly improved compared to the conventional two-coil system. When the distance between the transmitter coils and the receiver coils is 1.5 cm, the transfer efficiency is 85% at the frequency of 742 kHz. The power transfer efficiency can be optimized by adding magnetic enhanced resonators. The receiving voltage signal is converted to a stable output voltage of 3.3 V and a current of 10 mA at the distance of 2 cm. In addition, the output current varies with changes in the distance. The whole implanted part is packaged with PDMS of excellent biocompatibility and the volume of it is about 1 cm3.
15330503
Wireless power transfer for free positioning using compact planar multiple self-resonators
In this paper, a wireless power transfer (WPT) system supporting free positioning in a large area is proposed. The main coupling unit of the proposed system consists of a transmitter with 5 self-resonators and a receiver with a self-resonator. By circuit analysis, the proposed system is analyzed. The fabricated coils are compact planar rectangular spiral types. The total size of the transmitter is 96 cm × 16 cm. The receiver is 10 cm × 10 cm. With the exception of the 5th resonator in the transmitter, their resonant frequencies are 6.78 MHz. There are some regions with less than 50% power transfer efficiency (called a dead zone). By changing the 5th resonator's frequency, the area of the dead zone can be reduced. When the 5th resonator's resonant frequency f5 is 6.78 MHz, a system has 40% dead zone of the transmitter and power transfer efficiencies of 57% ~ 87% in the other regions. On the other hand, when f5 is 6.38 MHz, a system has 10% dead zone and power transfer efficiencies of 70% ~ 86% in other regions. The measured power transfer efficiencies are approximately consistent with the calculated results.
596271
Optimal design of a wireless power transfer system with multiple self-resonators for an LED TV
This paper proposes an optimal design method in an asymmetric wireless power transfer (WPT) system for a 150 watt LED TV. The WPT system has three self-resonators: a Tx resonator, an Rx resonator, and an intermediate resonator. The Tx and Rx resonators are perpendicular and offset, respectively, to the intermediate resonator in the geometry. For optimal design, the WPT system is analyzed using an equivalent circuit. In particular, a calculation method for mutual inductance in the system is expressed. The calculation results of mutual inductance are used to determine the optimal position of each self-resonator for maximizing the power transfer efficiency. For verification, a WPT system for a 150 watt, 47 inch LED TV is fabricated at 250 kHz. The WPT system exhibits wireless power transfer efficiency of 80%.
44967680
Cross coupling effects of poly-phase bi-directional inductive power transfer systems used for EV charging
Bi-directional inductive power transfer (BD-IPT) systems are preferable for applications such as Electric Vehicles (EVs) and wireless integration of EVs with the utility grid (V2G). In particular, poly-phase BD-IPT systems are used in high power applications and for rapid charging of EVs but their performance is severely compromised by the cross-coupling effects between phases and the misalignment of charging pads or coils. This paper therefore presents a generalized mathematical model to investigate the cross-coupling effects caused by pad-misalignments and corresponding impacts on the power flow of ploy-phase BD-IPT systems used for EV charging. Using the proposed model, the charging behavior of an EV, based on a 3-phase BD-IPT system, is investigated under different operating conditions, analyzing the sensitivity of power flow and direction to cross coupling. Results are presented in comparison to simulations to demonstrate the accuracy of the proposed mathematical model and as well as to show that the changes in power flow and direction can be somewhat compensated for by the individual control of phases.
20420398
Interphase Mutual Inductance in Polyphase Inductive Power Transfer Systems
Roadway powered electric vehicles with minimal or no onboard energy storage have been proposed for many years, but the concept has only recently become feasible via three-phase inductive power transfer (IPT) systems. A wide zone can be created over which power transfer is relatively constant. This gives good tolerance to the alignment of the pickup relative to the track allowing simple low-cost pickup structures to be used. While three-phase IPT tracks make the vehicle pickup and power transfer simpler, they are difficult for the power supply to drive due to the presence of mutual coupling between the track phases resulting from the physical layout of the track. These mutual inductances induce voltages within each track phase that, because of the inductor-capacitor-inductor network, cause large currents within the power supply inverter and imbalances within the system. This paper presents an analytical assessment of the problems caused by the interphase mutual inductance, and three possible solutions. Two of the methods involve modifications to the track layout to alter or remove the mutual inductances, while the third and preferred technique requires additional ferrite cores between the various phases to compensate this adverse mutual inductance without affecting the power transfer to the pickup loads.
22463025
Generalized Models on Self-Decoupled Dual Pick-up Coils for Large Lateral Tolerance
Self-decoupled dual pick-up coils for large lateral tolerance and low electromagnetic field for pedestrians are proposed. Analytical models are developed that are applicable to any self-decoupled coils, regardless the coil types such as single/dual pick-ups and core/coreless coils. An optimum decoupling distance between adjacent pick-up coils is determined and found to be independent of the existence of a core plate. Maximum load power over a large lateral tolerance is obtained for the optimum decoupling distance. The proposed models are so general that they can be applied to any self-decoupled pick-up coils for stationary charging and dynamic charging systems. Moreover, the self-decoupled coils are compatible with any compensation method such as serial, parallel, and serial-parallel. A prototype system of 1.5 kW and Q = 60 for roadway powered electrical vehicles was implemented and showed fairly good agreements with the theoretical models and simulations. The measured lateral tolerance was 90 cm, which is about 1.5 times of the coil width.