Bidirectional Power Transfer Research Articles

A Bidirectional Simultaneous Wireless Power and Data Transfer System with Non-Contact Slip Ring

A Bidirectional Simultaneous Wireless Power and Data Transfer System with Non-Contact Slip Ring

DAB-Based Bidirectional Wireless Power Transfer System with LCC-S Compensation Network under Grid-Connected Application

To realize two-way power transfer without physical connections under a grid-connected application, bidirectional wireless power transfer (BDWPT) is introduced. This paper proposes an LCC-S compensated BDWPT system based on dual-active-bridge (DAB) topology with the minimum component counts. LCC-S is designed to be a constant voltage (CV) network. To obtain the power transmission characteristics of the system, a mathematical model based on the fundamental harmonic approximation (FHA) method is established, and the result shows that the direction and amount of transfer power can be controlled by changing the magnitude of output voltages of either/both side of H-bridges. The reactive power of the system can be controlled to be zero when the output voltages of two H-bridges are in the same phase. Compared with DAB-based BDWPT systems with constant current (CC) compensation networks, the proposed structure has better transfer power regulation capability and easier control of the direction of power flow. A 1.1 kW experimental prototype is built in the laboratory to verify the characteristics of the proposed system. The results indicate that the power transfer characteristics of the proposed BDWPT system match its mathematical derivation results based on the FHA model.

Design of adaptive speed controllers for matrix‐converter‐based interior permanent magnet synchronous motor drive systems

AbstractInterior permanent magnet synchronous motors (IPMSMs) which are driven by matrix converters have many advantages, including one‐stage power conversion, high efficiency, bidirectional power transfer, near unity input power factor, and low input current harmonics. However, the virtual DC‐link voltages of matrix‐converters vary from 0.866 to and the current commutations of matrix‐converters create serious three‐phase stator harmonic currents as well. Moreover, matrix‐converter‐based IPMSM drive systems, in general, have very large external loads, which require advanced control methods. To solve these problems, two adaptive controllers, including a model reference adaptive controller and a self‐tuning controller, are investigated in this article for matrix‐converter PMSM drive systems. From the experimental results, the proposed two adaptive speed controllers provide excellent dynamic responses, which are superior to PI speed controllers, including faster transient responses, better tracking abilities, and greater robustness. As a result, this proposed matrix‐converter‐based IPMSM drive system is very suitable in industrial applications.

Analysis and Design of Wireless Bidirectional Power and Data Transfer With Decoupled DD-R Coil Geometry

Analysis and Design of Wireless Bidirectional Power and Data Transfer With Decoupled DD-R Coil Geometry

Converter-based multi-frequency power transfer system for efficient energy packet transmission in the energy internet

The energy internet concept involves the transmission of energy in discrete packets, akin to the information internet's principle. The energy internet must adopt a decentralized configuration and enable bidirectional and simultaneous power transfer. This raises the problem of congestions during the energy packet dispatching process. To address potential congestion issues, we propose a three-phase multi-frequency power transfer system (MFPTS) where the positive-sequence fundamental frequency component is supplemented with the zero-sequence third and the negative-sequence fifth harmonic components. By using such signals with proper amplitudes, the harmonics are added to the voltage without changing the peak amplitude but increasing the rms value. To exert complete control over the different frequencies employed within the MFPTS, a decoupling method is necessary to separate these frequencies in the control system. This leads to creating three independent channels of power transfer by three frequencies without changing the existing infrastructure as these powers can be transferred within the same lines. This paper explores the feasibility of three-phase three-frequency power transfer by using three parallel power transfer channels, achieved through the utilization of three-phase grid-forming and grid-feeding converters. Using power converters provides the advantage of bidirectional power transfer and facilitates decentralization by serving as an interface between distributed power generation systems and the utility grid. These properties are essential for achieving optimal energy internet performance. The simulation and practical results prove that the proposed MFPTS could solve the energy packet dispatching congestion problem to have a reliable energy internet for the future.

Analytical investigation of interleaved input/output parallel DAB converter for grid scale battery storage

With the surge of integration of intermittent renewable energy sources into the grid the installation of large scale battery energy storage is rising at a rapid rate to support the power system. The grid scale battery storage needs to be scalable with varying power system requirements. Parallel connected modular dual active bridge (DAB) converter with high frequency transformers interface can facilitate adjustable large power flow for grid scale battery storage. The high gain between LV and HV side can be achieved using isolated high frequency transformers and parallelism of the DAB converter with efficient and smooth bidirectional power transfer capability. In this paper, a generalized interleaving operation (ILO) on both input and output parallel connected DAB (IOPDAB) converter has been proposed for large energy storage capability and to enable improved quality of power flow. The generalized expressions of peak currents, average circulating current and active power flow, has been developed for the IOPDAB converter with n-parallel connected DAB modules. A detailed analytical investigation has been carried out to show the improved currents profile in both input and output sides in the interleaved mode. The operating performance of the IOPDAB converter has been shown using PSCAD/EMTDC software based simulation. The results are verified through laboratory experimental setup with two interleaved I/O parallel DAB using Spartan 3AN FPGA processor as controller. A performance comparison has been done with the non-interleaving operation (NILO) and interleaving operation (ILO) modes, and it is shown that the ILO mode has better performance in terms of efficiency, Input/output ripple current reduction, increased ripple frequency and circulating current minimization.

Analysis of Deadtime Effects and Optimum Deadtime Control for Bidirectional Inductive Power Transfer Converters

Analysis of Deadtime Effects and Optimum Deadtime Control for Bidirectional Inductive Power Transfer Converters

An I/Q Phase Detection-Based Harmonic- Insensitive Phase Synchronization Method for Bidirectional Wireless Power Transfer System

An I/Q Phase Detection-Based Harmonic- Insensitive Phase Synchronization Method for Bidirectional Wireless Power Transfer System

Assessment of Time and Frequency Domain Models of Bidirectional LCC-LCC Inductive Power Transfer Systems

Assessment of Time and Frequency Domain Models of Bidirectional LCC-LCC Inductive Power Transfer Systems

Analytical Selection of Leakage Inductance for Single-Phase Dual Active Bridge Converters

The single-phase dual active bridge (DAB) DC/DC converter is a vital component in modern power electronics systems, facilitating efficient bidirectional power transfer between various energy sources and loads. One of the critical aspects in the design of such converters is the selection of an appropriate leakage inductance, as it significantly affects the circulating power within the converter. This study investigates the influence of inductance on the reactive power flow and introduces an analytical formula for calculating the necessary leakage inductance based on the specified rated power of the DAB converter. By employing the inductance values determined through the proposed formula, the developed power control-based modulation method, implemented in discrete time, successfully achieves zero reactive power caused by the first harmonic components under all load conditions. This selection of leakage inductance optimizes the performance of the converter ensuring efficient power delivery across various applications. The applicability of this method extends to various DAB applications, including electric vehicles, integration with asynchronous microgrids, and aerospace systems.

Optimal event‐triggered control for wireless power transfer system in electric vehicles

AbstractThis study focuses on stabilizing a bidirectional inductive wireless power transfer (WPT) system using an event‐triggered approach. It is only assumed the inductor currents on both the primary and pickup sides are measurable, and they are sent synchronously to the controller via a digital channel. To estimate the unmeasured states and maintain plant stability, a full‐order state observer and an observer‐based controller have been developed. The control parameters are optimized through a genetic algorithm to achieve the desired output response. An emulation methodology is then applied to create an output‐based event‐triggering condition. This condition ensures the stability of the closed‐loop system even in the presence of communication constraints. To prevent Zeno sampling, a minimal time interval between two transmissions is enforced using time‐regularization techniques. Furthermore, the performance of the event‐triggered controller is enhanced by solving a linear matrix inequality condition, which further reduces the number of transmission instances. The methodology offers a systematic and optimal design for the bidirectional inductive WPT system. It eliminates the need for manual tuning of control parameters, which is particularly beneficial given the system's complex nature. To address both continuous‐time and discrete‐time dynamics, the entire system is represented as a hybrid dynamical system, making it more intuitive for networked control systems. The efficiency of this approach is assessed through numerical simulations of a WPT system, demonstrating its effectiveness. The results show that the average intertransmission interval has been increased from 0.0799 to 0.1782 s, that is, the proposed event‐triggering strategy reduced the number of transmissions to more than 50% compared with conventional periodic sampling.

Energy-efficient resource allocation for bidirectional wireless power and information transfer over interference channels

Energy efficiency is an important performance metric for the sustainable operation of energy-limited communication networks. This study investigates an energy-efficient resource allocation strategy to maximize the energy efficiency of wireless-powered bidirectional communication over interference channels. The receivers in the system harvest energy and decode information simultaneously using a time switching or power splitting policy from data signals sent by transmitters in the forward link. The harvested energy is subsequently used to send response signals back to the transmitters in the backward link. Our objective is to jointly optimize the transmit power of the transmitters and the energy harvesting ratio of the receivers to maximize the energy efficiency of the entire system while maintaining the minimum required data rates in both the forward and backward links. Considering the non-convexity and NP-hardness of this optimization problem, we first apply nonlinear fractional programming and a dual method to derive an analytical expression for each control parameter and then propose an iterative algorithm to find suboptimal solutions with low computational complexity. The simulation results show that the proposed algorithm adjusts both the transmit power and energy harvesting ratio adaptively considering the co-channel interference and thus achieves near-optimal energy efficiency performance within a short computation time.

A Control Strategy for Achieving Constant Voltage Output with an Extensive ZVS Operating Range in Bidirectional Wireless EV Charging Systems

Variations in the coupling coefficient of loosely coupled transformers and dynamic loads have a significant impact on the overall performance of bidirectional inductive power transfer (BIPT) systems. However, a wide range of load and coupling coefficient variations are common in the actual charging process, which may cause the converter on both sides to operate in a hard switching state, resulting in switching noise, reduced efficiency, and potential safety concerns. In this paper, a triple-phase-shift control (TPSC) strategy is proposed to study the zero-voltage switching (ZVS) operating range and constant-voltage output (CVO) characteristics of the double-side-LCC (DS-LCC) topology. To ensure a CVO over the wide range of coupling coefficient variations, a dual-phase-shift control is introduced for AC voltage matching. Based on this, the third phase-shift angle control between the converters on both sides is introduced to ensure the ZVS realization. Meanwhile, the time-domain model is developed to analyze the rationality of the proposed third phase-shift angle and the ZVS operating range. Finally, the effectiveness of the proposed TPSC strategy is validated through a 1.5 kW experimental prototype with an air gap of 100–150 mm.

Real-Time Hardware Emulation of Microgrid Forming Wireless Power Transfer Systems

The prevalence of wireless charging approaches has manifested a grid-supporting potential which can be evaluated by hardware-based methodologies. In this work, real-time emulation of a bidirectional wireless power transfer (WPT) system capable of DC microgrid formation is investigated on the field-programmable gate array (FPGA). Following a detailed analysis of the transfer characteristics of the dual-active bridge with a series-compensated resonant tank in between, a unified control scheme utilizing a phase-shift strategy is proposed for a flexible voltage or current regulation, thereby enabling the DC microgrid-forming capability. Electromagnetic transient modeling is then carried out so that an accurate digital emulation platform is feasible for prototyping. The fact that the WPT has a high frequency compels a small computation step size, which poses a dramatic challenge to real-time execution. A partition-iteration approach is therefore proposed for matrix dimension reduction which ultimately results in an alleviated processing burden. In the meantime, the parallelism of configurable logic blocks and the pipelined architecture of the FPGA are explored to achieve a low hardware latency. The analytical models, as well as the proposed control method, are validated experimentally, and then real-time hardware emulation of a DC microgrid consisting of WPT systems is performed for an integration study.

Research on MLD Modeling and Predictive Control of Magnetically Coupled Resonant Bidirectional WPT System

The recent studies on magnetically coupled resonant bidirectional wireless power transfer (MCR-BWPT) systems disregard the challenges posed by nonlinearity, discrete switching action, and hybrid properties within the system. This research focuses on the D-LCL resonant compensation topology MCR-BWPT system. The switch tube’s switching state dictates the division of various working modes and the determination of the switching conditions between them. The coupling relationship between the continuous dynamic characteristics of the system and discrete events and the constrained conditions of the system are derived. The Hybrid System Description Language (HYSDEL) is used to build the Mixed Logic Dynamic (MLD) model of the system. The MLD model is employed as the prediction model, and the hybrid model predictive controller of the MCR-BWPT system is constructed according to the quadratic performance index. Finally, to verify the accuracy of the MLD model and the feasibility of the control strategy, the simulation model of the MLD model is established in MATLAB/Simulink. The study’s findings show that, in terms of response time at system startup and power fluctuation suppression, the approach put forward in this research performs better than both the conventional bilateral dual-phase-shift control strategy and the PQ-based bilateral power control strategy. The MCR-BWPT system can operate more steadily now that PQ’s bidirectional power control technique is in place. The system’s forward and reverse transmission efficiency is increased by 0.29% and 0.32% compared to the conventional bilateral dual-phase-shift control approach; the increases are 0.28% and 0.09%, each compared to the bilateral power control strategy based on PQ.

Novel Meta-Fractal Wearable Sensors and Antennas for Medical, Communication, 5G, and IoT Applications

Future communication, 5G, medical, and IoT systems need compact, green, efficient wideband sensors, and antennas. Novel linear and dual-polarized antennas for 5G, 6G, medical devices, Internet of Things (IoT) systems, and healthcare monitoring sensors are presented in this paper. One of the major goals in the evaluation of medical, 5G, and smart wireless communication devices is the development of efficient, compact, low-cost antennas and sensors. Moreover, passive and active sensors may be self-powered by connecting an energy-harvesting unit to the antenna to collect electromagnetic radiation and charge the wearable sensor battery. Wearable sensors and antennas can be employed in smart grid applications that provide communication between neighbors, localized management, bidirectional power transfer, and effective demand response. A low-cost wearable antenna may be developed by etching the printed feed and matching the network on the same substrate in the printed antenna. Active modules may be placed on the same dielectric board. The antenna design parameters and a comparison between the computation and measured electrical performance of the antennas are presented in this paper. The electrical characteristics of the new compact antennas in the vicinity of the patient’s body were simulated by using electromagnetic simulation techniques. Fractal and metamaterial efficient antennas and sensors were evaluated to maximize the electrical characteristics of smart communication and medical devices. The dual- and circularly polarized antennas developed in this paper are crucial to the evaluation of wideband and multiband compact 5G, 6G, and IoT advanced systems. The new efficient sensors and antennas maximize the system’s dynamic range and electrical characteristics. The new efficient wearable antennas and sensors are compact, wideband, and low-cost. The operating resonant frequency of the metamaterial antennas with circular split-ring resonators (CSRRs) may be 5% to 9% lower than the resonant frequency of the sensor without CSRRs. The directivity and gain of the metamaterial fractal antennas with CSRRs may be up to 3 dB higher than the antennas without CSRRs. The directivity and gain of the metamaterial fractal passive sensors with CSRRs may be up to 8.5 dBi. This study presents new wideband active meta-fractal antennas and sensors. The bandwidth of the new sensors is around 9% to 20%. At 2.83 GHz, the receiving active sensor gain is 13.5 dB and drops to 8 dB at 3.2 GHz. The receiving module noise figure with TAV541 LNA is around 1dB.

Research on a soft-start method for LCC-LCC compensated bidirectional wireless power transfer system

The increased popularity of electric vehicles and the pursuit of user convenience makes bidirectional wireless power transfer (BWPT) an attractive technology for charging batteries. To improve the transmission efficiency of BWPT and limit the external radiated magnetic field, it is necessary to ensure the zero-voltage switching (ZVS) operation of the converter on the transmitter-side and limit the transient start-up current of the inverter when the system is working. To solve this problem, this paper proposes a soft-start modulation strategy based on an H-bridge inverter on the transmitter-side. First, the circular characteristics of dual LCC compensation topology are analysed based on an equivalent circuit. Secondly, according to the characteristics of the input impedance angle and current of the transmitter-side, a soft-start control method combining frequency and phase shift control is proposed. Finally, the feasibility of the proposed soft-start modulation strategy is verified on a prototype.

Coupled-Inductor-Based Bidirectional Resonant Converter With Reduced Component Count and Load-Independent Voltage Gain

The bidirectional DC/DC converter (BDC) is a critical part to interface the DC-bus with energy storage system (ESS) in DC microgrid. This paper proposes a coupled-inductor based bidirectional resonant converter with center-aligned pulse width modulation (PWM) modulation method and reduced component count. The structure of dual half-bridges with coupled inductor makes the current analysis more complex than the full-bridge PWM resonant converter. Hence, a method of performance analysis based on the symmetrical pi model is proposed and the corresponding parameter design process is introduced. In addition, fixed switching frequency operation, load-independent voltage gain, full-load range zero-voltage-switching (ZVS), automatic bidirectional power transfer and bidirectional power limitation can be realized in the proposed PWM converter. An experimental prototype with rated power of 1000W is built to demonstrate the operation and performance of the proposed converter.

A Bidirectional Wireless Power Transfer System with Integrated Near-Field Communication for E-Vehicles

This paper presents the design of a bidirectional wireless power and information transfer system. The wireless information transfer is based on near-field technology, utilizing communication coils integrated into power transfer coils. Compared with conventional far-field-based communication methods (e.g., Bluetooth and WLAN), the proposed near-field-based communication method provides a peer-to-peer feature, as well as lower latency, which enables the simple paring of a transmitter and a receiver for power transfer and the real-time updating of control parameters. Using the established communication, control parameters are transmitted from one side of the system to another side, and the co-control of the inverter and the active rectifier is realized. In addition, this work innovatively presents the communication-signal-based synchronization of an inverter and a rectifier, which requires no AC current sensing in the power path and no complex algorithm for stabilization, unlike conventional current-based synchronization methods. The proposed information and power transfer system was measured under different operating conditions, including aligned and misaligned positions, operating points with different charging powers, and forward and reverse power transfer. The results show that the presented prototype allows a bidirectional power transfer of up to 1.2 kW, and efficiency above 90% for the power ranges from 0.6 kW to 1.2 kW was obtained. Furthermore, the integrated communication is robust to the crosstalk from the power transfer and misalignment, and a zero BER (bit error rate) and ultra-low latency of 15.36 µs are achieved. The presented work thus provides a novel solution to the synchronization and real-time co-control of an active rectifier and an inverter in a wireless power transfer system, utilizing integrated near-field-based communication.

A Hybrid Modulation Strategy for LCC–LCC Compensated Bidirectional Wireless Power Transfer System to Achieve High Efficiency in the Whole Operating Range

A hybrid modulation strategy is proposed for the LCC-LCC compensated bidirectional wireless power transfer system (LCC-BWPT), which aims to boost the efficiencies in the whole operating range. The basic operating modes of LCC-BWPT with the hybrid modulation strategy are analyzed, and the unified discrete-time model is then established based on the full-mode operation, which can accurately describe the state variables under all operating modes. Based on the model, the criteria for optimal operation are put forward in consideration of three working processes of LCC-BWPT, i.e., the constant current (CC) charging process, the constant voltage (CV) charging process, and the CC discharging process. The optimal control variables in three working processes are derived respectively, which realize full zero-voltage switching (ZVS) operation and minimize the reactive current. On this basis, an optimal modulation strategy featuring high efficiency performance is proposed for LCC-BWPT. Besides, a control method independent of the real-time wireless communication is developed for LCC-BWPT with the optimal modulation strategy. Finally, a 1.2kW prototype is applied, and experimental results verify the effectiveness of the proposed optimal modulation strategy, where the efficiencies are improved in the whole operating range.