Inductive Power Research Articles

Joint Real-Time Identification for Mutual Inductance and Load Charging Parameters of IPT System

Accurate and fast identification for mutual inductance and load charging parameters of inductive wireless power transfer (IPT) system is essential for impedance matching, and the output control of communication-free IPT system. A joint real-time identification method for mutual inductance and load charging parameters of IPT system is proposed in this paper. Only via measuring the RMS value of fundamental voltage and current on primary side, the double equivalent impedance modulus equations about mutual inductance and equivalent load resistance are established. To obtain real-time identification results of mutual inductance and equivalent load resistance from the high-order implicit function equations, an improved adaptive filtering algorithm based on Least Mean Squares (LMS) is proposed. Then, the identification values of load charging parameters are obtained according to the identified mutual inductance and equivalent load resistance. Finally, a 3.6kW platform is built to verify the validity of the proposed method. And the experiment results show that, compared with other existing achievements, the proposed method can identify <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">U_Bat</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_Bat</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_L</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> simultaneously in real-time without changing the system operation, and it has faster rate and higher accuracy of identification.

Studying Interoperability of Different Compensation Networks in Inductive Power Transfer Systems

The issue of interoperability between electric vehicles and different wireless chargers, resulting from the diverse compensation networks, is impeding the engineering application of IPT technology. The objective of the paper is to investigate the interoperability of different compensation networks for inductive power transfer systems. The study analyses three potential cases of compensation design, which include LCCS, SLCC, and LCCP compensation networks. To evaluate the performance of these networks, a proposed analytical methodology is utilized to delve into the power factor of the compensation networks. Additionally, in order to assess their sensitivity to parameter changes, the power displacement under mistuned conditions is calculated by adding additional series inductors to the main coil. Finally, the proposed analysis is validated by simulation models, which indicate that the SLCC network has better tolerance to parameter variations under mistuned conditions.

Voltage Regulating Strategy of a New LCC/S+L Inductive Power Transfer System

In the voltage control of the inductive power transfer (IPT) system, a cascaded DC-DC converter is normally adopted which reduces the power density. However, the wireless communication between the transmitter and the receiver may lead to a delay of control as well as communication instability. This paper proposes a new LCC/S+L resonance topology for the IPT system, which can realize single-stage voltage regulation on the receiving side with both buck and boost capability. Based on the fundamental wave analysis method, this paper analyzes the working principle of LCC/S+L resonant topology. Then the control strategy of the phase shift angle between bridges and within bridges is obtained by the voltage of both ends of the series inductor and the load voltage vector. It is verified by simulation that the proposed new resonance topology and control strategy can achieve output voltage regulation of 300-500 V with a constant 375 V input DC voltage.

Three-Leg DC–DC Converter for Efficient Inductive Power Transfer of Electric Vehicles for Wide-Range Battery Applications

The design of an inductive power transfer system for different electric vehicle (EV) models with widely varied battery pack voltages has been a challenging task. The majority of modern EV models are equipped with 400 V or 800 V battery packs. To charge both batteries efficiently, an additional DC-DC converter on the receiver side is employed, which reduces the overall system efficiency and also increases the cost. This article proposes a reduced switch count novel converter to charge distinct EV models without degrading the efficiency of the system. The proposed converter has two operating modes, a voltage doubler mode to charge an 800 V battery and a current doubler mode to charge a 400 V battery at the same power level. MATLAB/Simulink simulations have been carried out to verify the performance of the 3-leg converter for both 400 V and 800 V batteries at 7.2 kW. Furthermore, a laboratory prototype of the proposed converter for 500 W has been built using the SiC devices, and the results obtained are provided.

A Review of Power Transfer Systems for Light Rail Vehicles: The Case for Capacitive Wireless Power Transfer

Light rail vehicles (LRVs) are increasingly in demand to sustainably meet the transport needs of growing populations in urban centres. LRVs have commonly been powered from the grid by direct-contact overhead catenary systems (OCS); however, catenary-free direct-contact systems, such as via a “hidden rail”, are popular for new installations. Wireless power transfer (WPT) is an emerging power transfer (PT) technology for e-transport with several advantages over direct contact systems, including improved aesthetics and reduced maintenance requirements; however, they are yet to be utilised in LRV systems. This paper provides a review of existing direct-contact and wireless PT technologies for LRVs, followed by an in-depth critical assessment of inductive power transfer (IPT) and capacitive power transfer (CPT) technologies for LRVs. In particular, the feasibility and advantages of CPT for powering LRVs are presented, highlighting the efficacy of CPT with respect to power transfer capability, safety, and other factors. Finally, limitations and recommendations for future works are identified.

Balanced Dual-Side LCC Compensation in IPT Systems Implementing Unity Power Factor for Wide Load Range and Misalignment Tolerance

Misalignment tolerance and wide load range capability are necessary for a practical inductive power transfer (IPT) system. In pursuit of high-performance, input unity power factor and high efficiency are expected. In this paper, a balanced design method of dual-side LCC compensation is proposed to achieve input unity power factor over wide misalignment and load ranges. With the proposed method, dual-side LCC compensation is in a balanced state where zero phase angle frequencies coincide with designed voltage gain frequencies under coupling and load variations. Unity power factor can be implemented while maintaining voltage gain with frequency control. Possible output power versus frequency characteristics of this balanced dual-side LCC compensation are categorized and fully analyzed. One of them, with strong power regulation capability and high misalignment adaptability, is selected as the design target. Coil currents are optimized using a surplus degree of design freedom while selecting parameters. Unity power factor and coil current optimization ensure low losses in devices and coils, which benefits system efficiency. Thus, a wide load range, high misalignment tolerance, nearly zero reactive power, and high efficiency can be simultaneously implemented. The proposed method is verified on a 2.1kW prototype. The coil size of both primary and secondary sides is 600mm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">×</i> 600mm, and the air gap is 150mm. Load power varies from 10% to 100% within the coupling range from 0.15 to 0.35. Nearly unity power factor is realized under various working conditions. The maximum dc-dc efficiency reaches 96.4%.

An Novel Technique for Wireless Power Transfer Systems Based on the Parametric Set

High efficiency and high power level are important indicators of the Inductive Power Transfer (IPT) system. However, the problem of optimizing the efficiency of IPT has not been well solved, and improving control methods is one of the effective ways to solve this problem. In order to improve the existing secondary-side control scheme and achieve the goal of simultaneously achieving optimal transmission efficiency and stable output, this paper suggests a parameter-based control strategy for coordinating the primary and secondary sides in the IPT system. This paper suggests a parameter-based control strategy for coordinating the primary and secondary sides in the IPT system. The paper develops a model of the IPT system to find the best load, then analyzes the active rectifier, phase shift angle, and load relationship to create a parameter set for controlling quantities like α and β. From there, a new control strategy is proposed and its effectiveness is confirmed through simulations. The proposed strategy enhances transmission efficiency and output stability of the IPT system, making it highly applicable in areas like electric vehicle charging and wireless charging devices.

DESIGN OF WIRELESS EV BATTERY CHARGING SYSTEM USING SQUARECIRCULAR COUPLED COILS WITH DIFFERENT MISALIGNMENTS

Now a days, inductive power transfer (IPT) has gained a lot of attention from researchers as it has ease of use and realiability for electric vehicle (EV) battery charging systems. This paper examines the increasing attention from researchers towards inductive power transfer (IPT) as a means of charging electric vehicle (EV) batteries. This interest originates from the user-friendly characteristics and notable reliability associated with IPT. The evaluation of mutual inductance (MI) holds importance within the domain of Inductive Power Transfer (IPT) systems, as it serves a critical function in enabling effective power transfer. Therefore, it is essential to perform a comprehensive analysis of the mutual inductance between the two coils that are connected through inductive coupling. This study provides an examination of mutual inductance (MI) and efficiency within the context of interoperability conditions of interconnected coils. The transmitter coil is represented as a square structure, denoted as TxS, whereas the receiving coil is represented as a circular structure, denoted as RxC. Furthermore, the application of ferrite cores and steel chassis inclosures, in combination with coils, is utilised for the objective of electric vehicle (EV) battery charging. The magnetic induction (MI) analysis is performed by the utilisation of finite element method (FEM) simulation. The finite element method (FEM) simulation outcomes of the interconnected coils with misalignments, encompassing both non-core and steel chassis configurations, are juxtaposed with the corresponding empirical observations.

Variable Inductor Control for Misalignment Tolerance and Constant Current/Voltage Charging in Inductive Power Transfer System

In wireless power transfer system, not only the mutual inductance variation but also the self-inductance variation can be occurred under the misalignment condition. In light of the Unmanned Aerial Vehicles, the variation of the secondary self-inductance and mutual inductance are significantly under the misalignment condition. In order to stabilize the output voltage and current and achieve near-ZPA (near-zero phase angle) of the input impedance. A variable inductor control is presented in this paper, which regulate the inductance of the secondary side by adjusting the dc bias current under large <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> variation. The proposed control method does not need any auxiliary circuit, and constant current-constant voltage (CC-CV) charging can be achieved by controlling the duty cycle of the boost converter. To verify the proposed control method, a 500-W prototype was set up in the laboratory, and the variable inductor control method ensures a stable output voltage and current with horizontal and vertical offsets of 200 mm and 92 mm, respectively. Additionally, communication is not need between primary and secondary side, and the results show that the maximum efficiency is 92.9%, which is 2.3% higher than the conventional dc-dc regulation method.

Evaluation and Suppression of Oscillations in Inductive Power Transfer Systems With Constant Voltage Load and Pulse Skipping Modulation

This paper identifies how Constant Voltage Load (CVL) characteristics cause Inductive Power Transfer (IPT) systems to exhibit a poorly damped oscillation mode. When operated with pulse skipping strategies such as Pulse Density Modulation (PDM), the skipped voltage pulses can excite this mode and cause severe oscillations that do not appear in systems with a constant resistance load (CRL). The critical mode is identified from a linearized state-space model of the system and two control approaches are proposed for attenuating the oscillations in current amplitude and power flow. Firstly, the influence of the operating frequency on the critical eigenvalue is analyzed and it is shown how slightly off-resonant operation can increase the damping of the oscillation mode. Secondly, an active damping method based on sending current feedback control is studied. The active damping is based on Phase Shift Modulation (PSM) with limited phase shift angles applied to the PDM signal when oscillations are detected. The effectiveness and feasibility of the proposed methods are validated by simulations and experimental results from a small-scale laboratory prototype.

Wearable Transmitter Coil Design for Inductive Wireless Power Transfer to Implantable Devices.

Wireless endovascular sensors and stimulators are emerging biomedical technologies for applications such as endovascular pressure monitoring, hyperthermia, and neural stimulations. Recently, coil-shaped stents have been proposed for inductive power transfer to endovascular devices using the stent as a receiver. However, less work has been done on the external transmitter components, so the maximum power transferable remains unknown. In this work, we design and evaluate a wearable transmitter coil that allows 50 mW power transfer in simulation.Clinical Relevance-This allows more accurate measurements and precise control of endovascular devices.

Wireless power transfer pulse charging of lithium-ion battery

In Wireless Power Transfer (WPT), the constant current-constant voltage (CC-CV) technique has been considered a standard strategy for charging lithium-ion (Li-ion) batteries. The pulse charging profile is used in this work in the Inductive Power Transfer (IPT) because of the inherent advantages of the pulse charging approach over the Constant Current-Constant Voltage method, such as improving the IPT-based charger efficiency. The LCC-Series compensation topology was chosen because it can meet the requirement of minimizing output characteristics' reliance on variations in Li-ion battery parameters. The pulse charging of the Li-ion battery on the second side is accomplished through phase-shifted control of the primary side high-frequency inverter. The control loops for pulse charging must be developed using the IPT transfer functions, according to the implementation technique. As a result, comprehensive modeling of the LCC-Series topology is presented, and the generated small-signal model is validated. Based on the confirmed model, the current and voltage loop control is constructed. The challenges associated with the pulse charging technique in the IPT system are explored, and a software-based solution to the problems highlighted is provided. The simulation and experimental results verified the validity of the conducted theatrical discussions.

A New Single-Cell Hybrid Inductor-Capacitor DC-DC Converter for Ultra-High Voltage Gain in Renewable Energy Applications

In this paper, a new single-cell hybrid switched inductor DC-DC converter is proposed to demonstrate the verification of ultra-high voltage gain in renewable energy applications (REA). The modification involves adding a single cell of an inductor with a diode and double capacitor to increase voltage transfer gain. Additionally, this modification helps prevent the input current from becoming zero, pulsating at very low duty cycles. The single cell of the hybrid inductor is interleaved with the main switch to reduce current stress when the capacitor of the single-cell inductor charge becomes zero. Moreover, the addition of a modified hybrid switch inductor with a capacitor, operating in dual boosting mode with a single switch, allows the converter to achieve ultra-high voltage gain. The proposed converter offers several advantages, including ultra-high voltage gain, high efficiency, low voltage stress on power MOSFETs, diodes, inductors, and capacitors, as well as low switching and conduction losses. Furthermore, the proposed converter utilizes transformerless and non-coupled inductors. Mathematical equations have been derived for the discontinuous conduction mode (DCM) and continuous conduction mode (CCM) and implemented using Matlab Simulink software to validate the results. In addition, a dual PI controller is designed for the proposed converter to verify the fixed output voltage. Experimental results have also been obtained for a 200 W prototype, with the input voltage varying between 20 V and 40 V, and an output voltage of 200 V at an efficiency of 96.5%.

Mutual and Self-Inductance Variation in Misaligned Coupler of Inductive Power Transfer System: Mechanism, Influence, and Solutions

Mutual and Self-Inductance Variation in Misaligned Coupler of Inductive Power Transfer System: Mechanism, Influence, and Solutions

Modular Coupler With Integrated Planar Transformer for Wireless EV Charging

A dynamic inductive power transfer (IPT) system is a safe and convenient solution for providing power to electric vehicles (EVs) while they are driving along a roadway. This technology can help reduce the size and cost of the bulky EV batteries without limiting the EV's travelling range. In recent years, practical aspects of dynamic IPT systems have been investigated to advance various IPT technologies from laboratories into roadways. This paper suggest an IPT roadway layout, focusing on a modular IPT system configuration with an integrated semi-loosely coupled planar transformer inside the in-road coupler to mitigate the installation and maintenance concerns of IPT roadways. The proposed configuration keeps the current in the couplers constant and load-independent while providing galvanic isolation between the coupler and the converter, and can be used as a replacement for the conventional LCL and transformer configuration. In order to reduce the number of components used in each module, each in-road coupler is connected to a common H-bridge through a single DC switch to enable individual couplers to be energized independently. Mathematical analysis and simulation results are provided, and validated using a scaled 7.7 kW prototype IPT system employing the proposed configuration.

Contactless-Sensor-Based Output Feedback Control With Maximum Efficiency Tracking Technique in Inductive Power Transfer Systems

To maximize the overall efficiency of a series-series inductive power transfer (SSIPT) system, the maximum efficiency tracking (MET) control should be employed. Based on a contactless current sensor which is designed for the mutual inductance estimation and the output voltage feedback, this paper proposes a novel MET control method for the SSIPT system with front-side and load-side converters. In this method, the output voltage of the rectifier on the load side is estimated and used as a control reference on the front side. Moreover, this paper analyzes the small-signal model of the SSIPT system and presents an impedance-based stability criterion. The factors which influence output feedback control are investigated, and a comprehensive control strategy based on the impedance stability criterion is developed. Finally, a 600 W prototype is built to validate the proposed method. MET control is implemented in a wide range of load variations, with a maximum efficiency drop of approximately 2.3% over a 100 mm misalignment. The results show that the proposed scheme significantly improves the robustness and response performance of the SSIPT system.

스마트 인버터의 연계점 전압 안정화를 위한 Volt-VAR 및 Volt-Watt 결합 제어

This paper proposes the combined Volt-VAR and Volt-Watt control method of smart inverters to stabilize the point of common coupling (PCC) voltage. The distributed energy sources (DER) using renewable energy such as solar and wind power are increasing because of environmental issues worldwide. When the DER increases, the PCC voltage fluctuates, which causes a decrease in grid stability and power quality. Smart inverter provides grid support function such as Volt-VAR and Volt-Watt control method to eliminate these problems. The Volt-VAR control method adjusts capacitive/inductive reactive power based on the PCC voltage. The Volt-Watt control method stabilizes the PCC voltage by reducing active power. The combined Volt-VAR and Volt-Watt control method reduces the active power while it controls the inductive reactive power to the maximum. This paper proposes the combined Volt-VAR and Volt-Watt control method to improve the stabilization effect of PCC voltage. The effectiveness of proposed method is verified by the simulation and experiment results.

Magnetic field intensity suppression using communication-less impedance adjustment for inductive power transfer systems

This letter describes the effectiveness of magnetic field intensity suppression through communication-less impedance adjustment in an inductive power transfer (IPT) system. The impedance adjustment scheme comprises a circuit configuration design that enables adaptive reactance adjustment using a field-effect transistor (FET) bridge-based variable reactor, which includes a coupling-coefficient estimation method for adjusting load resistance. The experimental results show that the load impedance that minimizes the magnetic energy stored in the IPT system can suppress the magnetic field intensity by up to 16.5% with only a 4.8% decrease in power transfer efficiency compared to load impedance that maximizes the power transfer efficiency.

AN EFFECTIVE METHOD OF ELECTRICAL VEHICLE CHARGING BY WIRELESS POWER TRANSFER

Electric vehicles are a viable solution for lowering greenhouse gas emissions. Electric vehicles not only reduce fossil fuel dependency, but they also minimise ozone damaging compounds and support large-scale renewable deployment. Despite extensive research on the qualities and attributes of electric vehicles, as well as the nature of their charging infrastructure, electric vehicle manufacturing and network modelling continue to evolve and be constrained. Various non-contact Plug-In Electric Vehicle charging methods are covered in this paper. They're either in the works or are already being used as flexible aftermarket choices in the light-duty vehicle industry. Wireless power transfer (WPT) is a commonly used name for wireless charging that includes inductive power transfer and magnetic resonance coupling. Wireless technology is still in its infancy, and there is a lack of standardisation, particularly in terms of interoperability, centre frequency selection, magnetic fringe field suppression, and power flow regulation methods.

Observer-Based Control of Inductive Wireless Power Transfer System Using Genetic Algorithm

In this paper, we studied the feedback stabilization of an inductive power transfer system based on available output measurement. The proposed controller relies on a full-order state observer in order to estimate the unmeasured state. The control design problem is challenging due to the large dimension of the closed-loop system, which requires too many tuning parameters to be determined when conventional control methods are employed. To solve this issue, we propose an LQR methodology based on a genetic algorithm such that the weighing coefficients of the cost function matrices can be automatically computed in an optimized manner. The proposed approach combines the method of eigenstructure assignment and the LQR technique in order to design both the controller and the observer gain matrices. The design methodology provides a systematic way to compute the parameters of the LQR technique for a wireless power transfer system in an optimized manner, which can be a useful design tool for many other applications. The effectiveness of the approach was verified by numerical simulation on the dynamic model of the wireless power transfer system. The results show that the proposed design outperforms conventional design methods in terms of a better performance and reduced design iterations effort.