Inductive Power Research Articles

Arbitrary power distribution and efficiency optimization for dual-receiver inductive power transfer system with variable coupling

Arbitrary power distribution and efficiency optimization for dual-receiver inductive power transfer system with variable coupling

State-Space Based Universal Time-Domain Model for Voltage-Fed Bidirectional IPT Systems

Conventional time-domain model of bidirectional inductive power transfer (BIPT) systems highly rely on specific compensation network and lacks universality. To address this issue, we propose a universal time-domain model for voltage-fed BIPT systems. The proposed state-space model applies to all compensation networks and resonant parameters, The input of the state space consists of the output voltage of the H-bridge. While the voltage combinations of the H-bridge are adaptive to different phase shift conditions. Based on the circuit analysis and by solving the state equations, analytical expressions for the state variables can be obtained. The time-domain analytical model is piecewise and accurately predicts the coil currents and capacitor voltages under all fundamental modulation schemes and compensation topologies. The simulation and experimental results of different compensation topologies and modulation strategies are presented, verifying the effectiveness of the proposed model. Compared with commercial software, the computation burden is obviously alleviated. The simulation is accelerated by 64 times than Simulink and 10 times than Psim.

Conditional Pulse Density Modulation for Inductive Power Transfer Systems

Conditional Pulse Density Modulation for Inductive Power Transfer Systems

ASSESSMENT OF THE POSSIBILITY OF EXPLORING THE WELL'S BACKWATER SPACE BY ACTIVE THERMOMETRY

The use of active thermometry based on local induction heating of the casing string has prospects for solving environmental problems in the study of idle wells. With an inductor power of 1 kW, even with small heating times, it is possible to create and register temperature anomalies in the casing.This article explores the possibility of using active thermometry to solve environmental problems in the study of idle wells.The idea is to measure the temperature of the casing before and after heating by the inductor for a certain time. Obviously, with fixed inductor power and heating time, the change in temperature of the section of the casing string heated by the inductor will depend on the heat exchange between the casing string, the downhole environment and the environment in the annular space. In this case, the conditions of heat exchange with the down hole environment at different depths may remain the same, but with the external environment surrounding the column may change. The reason for this may be a change in the contact of the column with the cement, the properties of the cement, the presence of vertical or horizontal fluid flows behind the well, etc.The paper presents a new analytical solution for calculating unsteady temperature in a metal casing caused by induction heating of a section of the column. The solution is based on a one-dimensional analytical model that takes into account heat exchange between the fluid and the casing, heat generation in the metal column when the inductor is turned on, and heat conduction losses in the cement and rock. To obtain a solution, the Laplace integral time transform method was used.The results of the study show that the amount of heating of the column changes depending on changes in heat exchange conditions and changes in the thermal activity of the environment behind the column. Significant differentiation of temperature along the depth of the well can be caused by a violation of the tightness of the cement ring, the movement of formation water and annular flow. This creates the prerequisites for using the active thermometry method to solve environmental problems in developed oil fields.

A Novel Coupler of Capacitive Power Transfer for Enhancing Underwater Power Transfer Characteristics

Compared to inductive power transfer (IPT) technology, capacitive power transfer (CPT) technology offers unique advantages such as being cost-effective, lightweight, and free from eddy-current losses, making it more suitable for underwater power transfer. Unlike air, water can conduct electricity and the electric conductivity of different kinds of waters varies with different ion concentrations, which would greatly affect the equivalent model of the underwater couplers. To address this issue, multiple types of underwater coupler working in different kinds of water are compared and analyzed. The influence of the electrical conductivity of water on the capacitive coupler is comprehensively analyzed, and the novel capacitive coupler and its equivalent model are proposed to improve power transfer efficiency. To verify the theoretical analysis, the double-sided LC-compensated CPT circuit is built and tap water is used in the experiment. The experimental results are consistent with the theoretical analysis. In addition, the experimental results also validate the superiority of the proposed capacitive coupler compared to existing research.

Multi-channel inductive power transfer system based on ISOP topology

Multi-channel inductive power transfer system based on ISOP topology

Constant current/voltage characteristics inductive power transfer system with variable static S-T/FC compensation

Constant current/voltage characteristics inductive power transfer system with variable static S-T/FC compensation

Technical Reviews of Power Loss Optimization in High-Frequency PSiPs—In Relation to Power Switches and Power Inductors

Power losses of switches and inductors are consistent challenges that hinder the development of high-frequency power supply in package (PSiP). This paper investigates the roadmap for power loss optimizations of switches and inductors in high-frequency PSiPs. Firstly, a size and parallel quantity design method to reduce power loss in an integrated Si LDMOSFET is provided with comprehensive consideration of switching frequency and power levels. Secondly, quality factors of different air-core inductors are analyzed with consideration of geometric parameters and skin effect, which provides the winding structure optimization to reduce power losses. The power losses of the integrated Si LDMOSFET and air-core inductors are both reduced to less than 10% of the output power at 1~100 MHz switching frequency and 0.1~10 W power level. Finally, based on the above optimizations, power losses of switches and inductors are calculated with switching frequency and power level. Combining the calculated results, this paper predicts the efficiency boundaries of PSiPs. Upon efficiency normalization with consideration of input and output voltage levels, all the predictions are consistent with the published literature. The efficiency predication error is 1~15% at 1~100 MHz switching frequency and 0.1~10 W power level. The above power loss optimizations improve the efficiency, which provides potential roadmaps for achieving high-frequency PSiPs.

A Novel Magnetic Coupled Railgun System Based on Inductive Pulsed Power Supply—Preliminary Theoretical Analysis and Experiment Study

A Novel Magnetic Coupled Railgun System Based on Inductive Pulsed Power Supply—Preliminary Theoretical Analysis and Experiment Study

Inductive Power Transfer in Electric Vehicles: Past and Future Trends

Inductive Power Transfer in Electric Vehicles: Past and Future Trends

Novel Three-Phase to Single-Phase Matrix Converter Modulation Strategy for Bidirectional Inductive Power Transfer

Novel Three-Phase to Single-Phase Matrix Converter Modulation Strategy for Bidirectional Inductive Power Transfer

SIMP-Method Topology Optimization of Ferrite Structures in Inductive Power Transfer Systems

SIMP-Method Topology Optimization of Ferrite Structures in Inductive Power Transfer Systems

Thermal-Mechanical Behaviour of Road-Embedded Wireless Charging Pads for EVs

Road-embedded inductive power transfer (IPT) systems have the potential to accelerate the electrification of the transportation sector. For these systems to be economically viable, however, they need to have a similar durability and lifespan to those of asphalt roads. One area that has lacked investigation is thermally induced stresses in a primary IPT pad, which are caused by the increase in the temperature of the pad when it is energized and the differing thermal expansion of the materials within. This paper presents an experimental and a finite element-based methodology for investigating the thermal–mechanical behaviour of a ¼-scale double-D pad, which was energized while suspended in air, as well as energized when embedded in pavement. A focus was placed on the measurement and prediction of strains in the magnetic ferrite cores because of their brittleness. Ferrite strains were measured using a combination of resistive strain gauges and non-metallic fibre Bragg grating (FBG) sensors. Coupled electromagnetic–thermal–structural simulations were conducted to predict temperature and strains in the system, with temperature-dependent properties obtained through physical testing. At an ambient temperature of 50 °C, the temperature in the middle of the copper litz wire coil was predicted to be 100 °C in both the suspended and embedded case. There was an excellent correlation with the experimental results, with a difference of less than 10% for most temperature measurements. When energized, the pad was predicted to experience an upward bow due to its temperature rise, resulting in bending strains in the ferrite cores. At an ambient temperature of 50 °C, the maximum tensile strain in the ferrites of the embedded pad was measured to be 62 microstrains (με), with a root-mean square error that was 18 με across three sensors. The experimental and validated numerical methodology can be applied to full-scale operational IPT pads to analyse and improve their thermal–mechanical performance.

Evaluation of the behavior of the interface zone between an asphalt mixture and an inductive power transfer pad

Wireless charging of Electric Vehicles (EVs) is seen as part of an important strategy to reduce emissions from essential transportation trips of people and goods. Resonant Inductive Power Transfer (IPT) is used in the development of wireless charging systems for in-road charging systems. IPT pads are embedded in a pavement infrastructure to create a magnetic field that is coupled into a similar pad fitted underneath an EV. This is then converted to the voltage and current needed to charge the onboard battery. This method enables EVs to wirelessly receive a charge while stationary or in motion. However, ensuring the robustness of this integrated in-road system is essential. Poor interface bonding between a surrounding asphalt mixture and an IPT pad decreases the structural integrity within the IPT pad-asphalt pavement system, hence increasing the risk of damage to the system. The purpose of this study is to investigate the behavior of an IPT pad-asphalt interface zone by performing direct shear tests. In the experimental setup, a normal compressive load is applied to a three-layer cylindrical specimen, comprising an asphalt mixture, the interface material, and the material forming the outer containment layer of the pad. The influence of temperature, moisture, and normal stress on the interface shear strength is investigated. Among the three interface materials tested (epoxy bitumen, epoxy resin, and structural plastic adhesive), the epoxy resin material showed the highest shear strength at 25 °C. The interface shear strength and the shear stiffness decreased for all three materials with increasing temperature, with the epoxy bitumen material being the most temperature sensitive, yielding a decrease in strength of 77 % and stiffness of 62 % between 15 °C and 40 °C. Experiments were performed using an orthogonal test design. Five variables, known to affect the interface shear strength, each variable assuming three values, were considered. The results of a range analysis and analysis of variance (ANOVA) showed that temperature has the most significant effect on the shear strength of the interface zone, i.e. between the asphalt mixture and pad surfacing. Other important factors affecting the shear strength are the interface material and the shear deformation rate. A numerical study of a full-scale IPT-asphalt pavement system is presented to show the effect of the interface bonding condition on the longitudinal and transverse strains at the bottom of the asphalt layer and the fatigue life. The results of this study will be used in the design of an IPT pad-asphalt pavement system by minimizing the differential permanent displacements between an IPT pad and the surrounding asphalt pavement.

Numerical and Experimental Investigation of Time-Domain-Reflectometry-Based Sensors for Foreign Object Detection in Wireless Power Transfer Systems

Foreign object detection (FOD) is considered a key method for detecting objects in the air gap of a wireless charging system that could pose a risk due to strong inductive heating. This paper describes a novel method for the detection of metallic objects utilizing the principle of electric time domain reflectometry. Through an analytical, numerical and experimental investigation, two key parameters for the design of transmission lines are identified and investigated with respect to the specific constraints of inductive power transfer. For this purpose, a transient electromagnetic simulation model is established to obtain and compare the sensor impedance and reflection coefficients with experimental data. The measurement setup is based on parametrically designed sensors in laboratory scale, using an EUR 2 coin as an exemplary test object. Consequently, the proposed simulation model has been successfully validated in this study, providing a comprehensive quantitative and qualitative analysis of the major transmission line design parameters for such applications.

Design of Power Supply Based on Inductive Power Transfer System for Medium Voltage Direct Current Sensor

This paper proposes a medium voltage direct current (MVDC) sensor power supply method based on inductive power transfer (IPT). Given that MVDC distribution networks transmit power at high voltages (several tens of kV), control through sensors is necessary to prevent exacerbating MVDC distribution network accidents. Moreover, these high voltages in MVDC distribution networks mean that high voltage insulation is required between the sensor and the distribution line and for any power supply device electrically connected to the sensor. Therefore, this paper proposes a safe and reliable power supply method using the principle of IPT to maintain a suitable insulation distance between the distribution network and the current sensor supply line. After proposing and designing a transmitter/receiver pad and IPT system by considering the current sensor specifications, a 50-W experimental prototype is developed. The experiments demonstrated that the proposed IPT system can resolve concerns about the breakdown of insulation between distribution networks and power supply lines.

Load Modulation Feedback in Adaptive Matching Networks for Low-Coupling Wireless Power Transfer Systems

This paper explores the use of load modulation feedback (LMF) in adaptive matching networks (MN) for low-coupling inductive wireless power transfer systems, with an emphasis on its use in implantable medical devices. After deriving the handy expressions of link efficiency and modulation depth in the case of LMF in the case of loose coupling, a brief overview of the most common capacitive resonance networks is presented. In particular, the MN employing two capacitors in Series–Parallel and in Parallel–Series configurations allow adaptivity with a wide range of load conditions. Then, the authors describe an effective design procedure of an adaptive matching network with LMF for an inductive wireless power transfer system, exploring the trade-off between power efficiency and modulation depth. Analytical and electrical simulations show that the proposed simple modulation strategy can successfully achieve high power transfer efficiency while maintaining steady back telemetry under varying loading conditions.

Modeling and Control of a DC-DC Buck–Boost Converter with Non-Linear Power Inductor Operating in Saturation Region Considering Electrical Losses

The present work proposes a nonlinear model of a buck–boost DC-DC power converter considering the nonlinear magnetic characteristics of the power inductor and electrical losses of the system. The Euler–Lagrange formalism is used for formulating the proposed model. Previous research works have reported mathematical models to describe power inductor dynamics. However, a gap in the literature remains regarding modeling this kind of element when it operates within power converters. Also, a linear-based controller scheme is proposed to regulate a non-ideal buck–boost DC-DC power converter. A methodology for tuning the proposed controller is presented, which considers the nonlinear model structure of the power converter, the linearization procedure based on an identification process, and a frequency domain analysis based on the approximated linear model. Finally, the tuned control scheme is tested on the nonlinear model of the power converter under several operational conditions showing excellent performance by effectively regulating the output voltage. The results are compared with those derived from alternative control strategies, and a better performance is generally obtained.

Algorithm for passive reactive power compensation of an unbalanced three-phase four-wire system using capacitors ensuring minimum line losses

Currently in three-phase distribution networks, especially low-voltage networks, there are some inefficient powers. These are defined as reactive power, unbalanced power owing to linear loads, power owing to supply unbalanced voltage, and harmonic power. This has given rise to the concept of power quality. To improve power quality, devices called active filters have been developed. These devices eliminate all the inefficient power. However, for most processes, the elimination of reactive power needs to be from a price/performance perspective because the use of active filters is very expensive. Therefore, the use of capacitor banks in any of their versions (single-phase, three-phase, scalable battery, SVC, etc.) is the most economical and sufficient solution. In this study, a calculation algorithm is proposed to obtain compensators for the inductive reactive power of the load, consisting only of single-phase capacitor banks. These capacitors are designed to minimise losses in the supply line, which are lower than those obtained using the minimum loss line (MLL) strategy. The resulting compensator consists of three, two, or one capacitor, depending on the load characteristics.

Varied-Frequency CC–CV Inductive Wireless Power Transfer with Efficiency-Regulated EV Charging for an Electric Golf Cart

Wireless electric vehicle (EV) charging is an important operation for valuable EV options in modern life. Inductive wireless EV charging needs constant current and voltage (CC–CV) charge controllers. This paper presents 750 W variable frequency CC–CV inductive wireless charging for an e-golf cart 50 Ah 72 V Li-ion battery. Due to this system’s low power, the system’s efficiency may be weak; the secondary-side (SS) maximum efficiency-controlled (MEC) converter was validated. The golf cart’s battery characteristics were evaluated to design and experiment with inductive wireless power transfer (IPT) coils and an integration system for a 42 kHz resonant frequency. The CC–CV charged control is an infrastructural part of the H-bridge inverter at varied frequencies from 50 kHz to 56 kHz when the DC input voltage is 310 V, and in the range of 44 kHz to 46 kHz at the 155 V input. The results found the charging of 9 A CC, 82 V CV and 730 W. The 310 V input voltage system without the SS MEC converter’s efficiencies was 62% to 72% and it was improved to 65% to 81% using the SS MEC converter. Finally, the best cases were validated at the 155 V DC input voltage and the system with the SS MEC converter had 76% to 86% efficiency.