Power Pads Research Articles

Design and Control of Inductive Power Transfer System for Electric Vehicles Considering Wide Variation of Output Voltage and Coupling Coefficient

In this paper, a design and control scheme of the inductive power transfer (IPT) system for electric vehicles are proposed, considering a wide variation in output voltage and coupling coefficient. The characteristics of the proposed IPT system and a design method for the resonant network are suggested. By utilizing the battery management converter at the secondary side, the design and control can be simplified while managing the output voltage and power of the battery. In order to achieve high efficiency by reducing the voltage–ampere rating, zero phase angle tracking control is proposed. In addition, a phase-shift control is applied to the primary side to ensure the stable system operation by limiting output voltage. A 3.3-kW laboratory prototype with magnetic power pads is manufactured, and the validity of the proposed design and control is verified through experimental results using the laboratory prototype.

A broadband GaAs pHEMT low noise driving amplifier with current reuse and self-biasing technique

A K/Ka-band two-stage low noise driving amplifier using a 0.15 μm GaAs pHEMT for low noise technology is designed and fabricated. In order to achieve broadband driving capability with low power consumption, current reuse technique is adopted to feed both transistors with the same DC power supply, which theoretically cuts the total current consumption in half. In addition, self-biasing technique is utilized to minimize both external power supply pads and chip footprint, which reduces the number of supply pads to a minimum of two (1 power pad and 1 ground pad). The circuit topology analysis and design procedures are also presented with an emphasis on noise figure and P1dB optimization. The low noise driving amplifier demonstrates a − 3 dB bandwidth of wider than 11 GHz, a power gain of 17 dB, an in-band mean noise figure of 2.2 dB and an in-band mean output P1dB of 6 dBm. The DC power consumption is 9.1 mA@3.3 V power supply. The chip size is 1 mm × 1.5 mm with only 1 external DC feed pad (3.3 V) and 1 ground pad (0 V). With the performance comparable to typical two-stage dual-bias low noise driving amplifier counterparts, the proposed MMIC is more attractive to chip/system users in volume-limited and power-contrained applications.

Magnetic Analysis of Copper Coil Power Pad with Ferrite Core for Wireless Charging Application

Wireless charging can automate the charging of electrical devices, very quickly connected with IoT based smart systems. The efficiency of wireless charging collectively depends on the design of the power pad, the frequency level of power transfer, the distance between the transmitter and receiver, alignment between the coils. Coils design comprehend the shape of the coil, material of the coil used, the thickness of the wire used and core shape and material used in the core. The manuscript compares the power pad coil shapes, with the introduction of ferrite material core across the coils to design an extremely efficient power pad for the wireless charging of electric vehicle. A 3D finite element method was used for analysis, due to the unconventional distribution of the flux. Only three types of coils, D, DD, and DDQ, are taken for analysis of magnetic core introduction. The comparison is made based on simulation results, magnetic flux pattern as well as data imported from the results. Ansys 3D Maxwell simulation software is used to simulate the magnetic pattern of the power pad coils. Finally, the results show the DD type coil shows the best magnetic fields and the maximum coupling coefficient with the maximum misalignment tolerance and the ferrite core across the coils have aligned the magnetic flux pattern and slightly improved the coupling coefficient.

Coil Design Optimization of Power Pad in IPT System for Electric Vehicle Applications

The proper magnetic design is one of the most difficult and critical phases in developing an inductive power transfer system, especially for electric vehicle charging. In this communication, a fast and an efficient improved Tabu search algorithm coupled with 2-D finite-element analysis (FEA) was used to determine the optimum design parameters of power pads. A two-objective optimization problem was investigated considering the magnetic coupling, misalignment (horizontal, vertical, and rotational), as well as the cost. The double-D power pad structure was considered as a case of study, and the most effective design parameters were obtained. The 2-D FEA was utilized to calculate the coupling factor at different misalignment conditions. For verification purposes, the system coupling performance and cost are analyzed using the optimum design parameters and compared with three other designs presented in the literature. The proposed optimized design shows the best coupling performance with moderate cost. The results proved the validity and advantages of the proposed design methodology.

A Comprehensive Review of Wireless Charging Technologies for Electric Vehicles

The profitable commercialization and fast adoption of electrified transportation require fast, economical, and reliable charging infrastructure. This paper provides a comprehensive, state-of-the-art review of all the wireless charging technologies for electric vehicle (EVs), characteristics and standards available in the open literature, as well as sustainable implications and potential safety measures. A comparative overview of conductive charging and wireless charging is followed by a detailed description of static wireless charging, dynamic wireless charging (DWC), and quasi-DWC. Roadblocks, such as coil design of power pads, frequency, power level limitations, misalignment, and potential solutions, are outlined. The standards are then tabulated to deliver a coherent view of the current status, followed by an explanation of the crux of these standards. Necessity and progress in the standardization of wireless charging systems are then deliberated. Vehicle-to-grid application of wireless charging is reviewed followed by an overview of economic analysis, social implications, the effect on sustainability, and safety aspects to evaluate the commercial feasibility of wireless charging. This paper will be highly beneficial to research entities, industry professionals, and investment representatives as a ready reference of the wireless charging system of EVs, with information on important characteristics and standards.

Physics-Based Co-Simulation Platform With Analytical and Experimental Verification for Bidirectional IPT System in EV Applications

Inductive power transfer (IPT) technology has been approved to be convenient and reliable interface for charging and discharging the electric vehicles (EVs). Precise model for such system can help designers and researchers to anticipate, optimize, and evaluate its behavior amid the development. Thus, this paper presents a physics-based co-simulation platform for the bidirectional IPT system (BIPTS) in EVs’ applications. The platform is established through the coupling between finite element and circuit analysis. The power electronic converters and controllers are developed in Simulink ; and the power pads are modeled in Magnet environment. The two parts are lined together through the compatible Simulink plug-in tool. In addition, a state-space dynamic mathematical model for the same BIPTS is derived and implemented in MATLAB environment. A 1.2 kW BIPTS is analyzed under different dynamics by both models and the results are compared. The effect of the nonlinearities and the magnetic material characteristics on the BIPTS's performance is assessed, in terms of errors and harmonics analysis. The analysis considered both the full and light loading operating conditions in the system. Finally, a small-scale prototype for a BIPTS is built, tested, and compared with the co-simulation results for verification purposes. The proposed co-simulation could provide accurate prediction for the system's dynamics, during both charging and discharging operation. The scheme is generic and can be easily expanded to different pad structures, compensation networks, and converter topologies.

The Analysis of LCL Resonant Inverter for Inductive Power Transfer Application

Inductive power transfer (IPT) systems use the principle of magnetic coupling to transfer power through the air gap. A wireless battery charger is used as a case study. The resonant inverter is used to generate the high frequency current transmitting through the power pad. The basic topologies give the large inverter current with the large conduction loss. This paper proposes the LCL resonant voltage source inverter using low power device rating. The proposed IPT system has two operating points with different powers required. The ZVS operation region and two operating points are validated by the AC sweep of actual load and the frequency response of entire system. Finally, the experimental results at two operating points with the efficiency comparisons are included to verify the proposed system.

Sizing of Inductive Power Pads for Dynamic Charging of EVs on IPT Highways

In this paper, the physical sizing of inductive power transfer (IPT) power pads on a dynamic IPT highway is explored. Previous work has focused only on sizing for stationary IPT chargers, and this paper extends this analysis for double-D (DD) and DD quadrature-based power pads. First, a window function (here fitted using a Gaussian distribution) is created to model the power transfer profiles when individual primary pads on the highway are energized. An analytical expression is developed that can predict the resultant power profiles from energizing multiple primary pads, depending on the phase angle between the individual primary pad currents and the physical sizes of the IPT pads. A practical design example is then presented that shows how pads could be sized to allow for 10-kW power transfer to sedans and SUVs (air gaps ranging from 250–400 mm) with only a 25% reduction in power as they drive along the highway.

Magnetic Design Considerations of Bidirectional Inductive Wireless Power Transfer System for EV Applications

This paper presents a clear methodology for achieving the optimum design of LCL bidirectional inductive wireless power transfer system (BIWPTS) for electric vehicle applications. The proposed strategy depends on electromagnetic field computations joined with analytical models. A 3-D finite-element model for 8-kW polarized double-D power pad was modeled, optimized, and built. Moreover, the choice of the power factor correction and the impedance matching elements was investigated. Following the proposed design considerations, a BIWPTS model was developed in MATLAB Simulink and its outcomes were compared with the theoretical model results. In addition, a small scale prototype was assembled using the same design with reduced dc voltage levels. The models were tested during charging and discharging operation, and good correlation was seen between every one of them.

Performance Analysis of Magnetic Power Pads for Inductive Power Transfer Systems with Ferrite Structure Variation

In this paper, performance of rectangular shaped magnetic power pads for inductive power transfer (IPT) system according to ferrite structure is analyzed. In order to evaluate the influences of ferrite structure, six cases of magnetic power pads are proposed. Self-inductance, coupling coefficient, quality factor, and coil to coil efficiency are compared as the displacement increases in the direction of x or y axis. For accurate estimation, finite element method (FEM) simulation is used and loss components of the power pads are numerically calculated and considered. Through the simulation and measured results, effectiveness of protrusive and enveloping ferrite structure is identified.

Practical Bifurcation Criteria considering Inductive Power Pad Losses in Wireless Power Transfer Systems

In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.

Reduction of Noise Using Continuously Changing Variable Clock and Clock Gating for IC Chips

The performance of silicon chip depends on the operating voltage of the chip. The chip should be designed using proper power and ground bond pads to minimize the power supply noise. When the chip starts working from the sleep mode, then the sudden rise in current inside the chip causes $LdI/dt$ noise. This noise reduces the power supply voltage, which in turn reduces the operating frequency of the chip. This makes the chip manufacturer to sell products of high-performance chips at a lower operating frequency. In order to ramp this current slowly, an innovative and fundamentally new method is implemented. In this proposed method, we have increased the operating frequency inside the chip slowly (from $f_{\textrm {min}}$ to $f_{\textrm {max}}$ ) to control the current ramp and at the same time performed clock gating (CG) to minimize noise by suppressing the current drawn by the device. We have applied this concept of variable frequency together with CG in a 3-b up counter to demonstrate that one can construct a design where the clock can be modulated during its functional operation without any functional failure.

Efficient power pad assignment for multi‐voltage SoC and its application in floorplanning

SummaryMulti‐voltage techniques are being developed to improve power savings by providing lower supply voltages for noncritical blocks under the performance constraint. However, the resulted lower voltage drop noise margin brings serious obstacles in power/ground (P/G) network design of the wire‐bonding package. For voltage drop optimization, both block and power pad positions are important factors that need to be considered. Traditional multi‐voltage floorplanning methods use rough estimation to evaluate the P/G network resource without considering the locations of power pads. To remedy this deficiency, in this paper, an efficient voltage drops aware power pad assignment (PPA) method is proposed, and it is further integrated into a floorplanning algorithm. We first present a fast PPA method for each power domain by the spring model. Then, to evaluate voltage drops during floorplanning iterations, the weighted distance from the blocks to the power pads is adopted as an optimization objective instead of time‐consuming matrix computation. Experimental results on Gigascale System Research Center (GSRC) benchmark circuits indicate that the proposed method generates an optimized placement of power pads and floorplanning of blocks with high efficiency. Copyright © 2015 John Wiley & Sons, Ltd.

A Trust-Driven Placement Approach: A New Perspective on Design for Hardware Trust

During the last few years, hardware Trojan horses (HTHs) have become one of the most important threats to the security of very large scale integrated (VLSI) chips. Many efforts have been made to facilitate the process of HTH detection, mostly based on the power analysis of chips. The techniques would be more beneficial if trust-driven techniques are used during the system design. Whereas design for hardware trust (DFHT) is one of the fields of interest, most current approaches include ad-hoc and gate-level design techniques. This paper discusses the advantage of physical-level design approaches with integrated strategies for improving the HTH-detection probability. As a proof of concept, a placement technique is presented with the goal of enhancing the ability of HTH detection techniques based on local power signal analysis. Our results show that the background effects on power pads can be leveraged by a simple partitioning-based placement algorithm. Minimizing the background effects leads to a better Trojan-to-background-effect ratio and more (by about 1.7 times) Trojan detectability.

High fidelity biopotential recordings in mice using a novel telemetry implant

We have developed a fully implantable telemetry device for use in mice.The telemeter is able to measure biopotential signals (EEG, EMG, ECG) at a sampling rate of 2000 Hz. The device has a volume of 1.45 cc with a unique contour design for subcutaneous implantation in mice over 20 gm in weight. A novel aspect to the device is that it contains no battery. Power to run the telemeter is provided by a wireless power pad placed under the cage of the animal. This provides continual operation of the telemeter (>90% data collection in a 24 hour period) during a range of normal animal behaviours. We have assessed the ability of this device to record biopotential signals for up to 3 months. We believe this technology offers new experimental paradigms to be explored.

Determining the Physical Size of Inductive Couplers for IPT EV Systems

Due to increasing environmental concerns and decreasing fossil fuel supplies, electric vehicles (EVs) are fast becoming attractive alternatives to conventional fossil-fuel driven vehicles. Inductive power transfer (IPT) is a method that can be used to transfer power to EVs over an air-gap and can dramatically increase the range, convenience, and safety of EV battery charging. One of the major difficulties is determining the physical sizes of the primary IPT coupler, buried in the roadway, and the EV mounted secondary coupler. This is mainly due to the variation in vehicle classes and charging locations that may be encountered. This paper seeks to determine if suitably sized couplers can be selected, which can realize all these demands. A recently proposed EV charging coupler, known as the Double-D (DD), which has been shown to provide the best power to size ratio over typical expected air gaps is selected. As such a method to select the best design from eight approximately square DD couplers ranging from 300 to 1000 mm in length to meet the challenge of delivering high power over large air-gaps is presented. The performance of these couplers, or power pads, is simulated and the results can be used to select couplers for EV charging systems. A practical design example is presented involving the IPT charging of sedans and SUVs in multiple practical charging locations. The proposed pad sizes and systems are capable of transferring 10 kW to the EVs for realistic horizontal misalignments (±200 mm) and air-gaps (100-400 mm).

The maximum voltage drop in an on-chip power distribution network: analysis of square, triangular and hexagonal power pad arrangements

A mathematical model of the voltage drop which arises in on-chip power distribution networks is used to compare the maximum voltage drop in the case of different geometric arrangements of the pads supplying power to the chip. These include the square or Manhattan power pad arrangement, which currently predominates, as well as equilateral triangular and hexagonal arrangements. In agreement with the findings in the literature and with physical and SPICE models, the equilateral triangular power pad arrangement is found to minimize the maximum voltage drop. This headline finding is a consequence of relatively simple formulas for the voltage drop, with explicit error bounds, which are established using complex analysis techniques, and elliptic functions in particular.

A Single-Supply 84dB DR Audio-Band ADC for Compact Digital Microphones

A 20kHz audio-band ADC with a single pair of power and ground pads is implemented for a digital electret microphone. Under the limited power/ground pad condition, the switching noise effect on the signal quality is estimated via post simulations with parasitic models. Performance degradation is minimized by time-domain noise isolation with sufficient time-spacing between the sampling edge and the output transition. The prototype ADC was implemented in a 0.18µm CMOS process. It operates under a minimum supply voltage of 1.6V with total current of 420µA. Operating at 2.56MHz clock frequency, it achieves 84dB dynamic range and a 64dB peak signal-to-(noise+distortion) ratio. The measured power supply rejection at a 100mVpp 217Hz square wave is -72dB.

Design and Optimization of Circular Magnetic Structures for Lumped Inductive Power Transfer Systems

A solution that enables safe, efficient, and convenient overnight recharging of electric vehicles is needed. Inductive power transfer (IPT) is capable of meeting these needs, however, the main limiting factor is the performance of the magnetic structures (termed power pads) that help transfer power efficiently. These should transfer 2-5 kW with a large air gap and have good tolerance to misalignment. Durability, low weight, and cost efficiency are also critical. 3-D finite-element analysis modeling is used to optimize circular power pads. This technique is viable, since measured and simulated results differ by 10% at most. A sample of power pads was considered in this work, and key design parameters were investigated to determine their influence on coupled power and operation. A final 2 kW 700-mm-diameter pad was constructed and tested having a horizontal radial tolerance of 130 mm (equivalent to a circular charging zone of diameter 260 mm) with a 200 mm air gap. The leakage magnetic flux of a charging system was investigated via simulation and measurement. The proposed pads meet human exposure regulations with measurement techniques specific by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) which uses the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines as a foundation.

Specific "scientific" data structures, and their processing

Programming physicists use, as all programmers, arrays, lists, tuples, records, etc., and this requires some change in their thought patterns while converting their formulae into some code, since the "data structures" operated upon, while elaborating some theory and its consequences, are rather: power series and Pad\'e approximants, differential forms and other instances of differential algebras, functionals (for the variational calculus), trajectories (solutions of differential equations), Young diagrams and Feynman graphs, etc. Such data is often used in a [semi-]numerical setting, not necessarily "symbolic", appropriate for the computer algebra packages. Modules adapted to such data may be "just libraries", but often they become specific, embedded sub-languages, typically mapped into object-oriented frameworks, with overloaded mathematical operations. Here we present a functional approach to this philosophy. We show how the usage of Haskell datatypes and - fundamental for our tutorial - the application of lazy evaluation makes it possible to operate upon such data (in particular: the "infinite" sequences) in a natural and comfortable manner.