Load Coil Research Articles

Load shift keying communication techniques in implantable devices.

Inductive links represent a highly promising avenue for both powering and communicating medical implants. Yet they encounter challenges such as constrained communication distance and limited data rate. In Load Shift Keying (LSK), a switch in the secondary side of the inductive link can be placed in parallel with the load (Short-Circuit Technique - SCT), in series with the load (Open-Circuit Technique - OCT), or both (Dual Technique - DLT), to vary the impedance of the secondary. Hence, the impedance reflected to the primary side changes and is used to transmit information externally from the implant. Among these, DLT is a novel LSK technique proposed in this work, which becomes independent from the load on the implant side. This study compares these three methods, confronting measurements to simulations. The evaluation focused on variations in coil distance and load. The proposal is illustrated in the case of an implantable gastric stimulator, with specific constraints in secondary coil size and power requirements. The newly developed DLT consistently outshone SCT and OCT in extending the operational range of communication, registering a maximum modulation index of 0.797 and a bit error rate below 10- 7 at an operating distance of 95mm through the air. Its load-independent characteristic allowed DLT to surpass the performance of SCT and OCT, which were each advantageous under high and low loads, respectively. All these results are confirmed by a LTSpice simulation. Consequently, the communication techniques put forward in this work mark a significant progression in medical implant communications, enhancing coil-to-coil operational distance while adhering to a low carrier frequency.

WIRELESS CHARGING FOR ELECTRICAL VEHICLES

Nowadays Wireless power transmission (WPT) is popular and gaining technology finding its application in various fields. The power is transferred from a source to an electrical load without the need of interconnections. Wireless power Transmission (WPT) is useful to power electrical devices where physical wiring is not possible or inconvenient. The technology uses the principle of mutual inductance. One of the best future applications finds in automotive sector especially in Electrical Vehicles. This project deals with research and development of wireless charging systems for Electric Vehicles using Wireless transmission. The main goal is to transmit power using resonance coupling and to build charging systems. The System deals with AC source, transmission coil, reception coil, converter and electric load which are battery. As Electric Vehicles (EVs) continue to gain popularity as a sustainable transportation solution, the need for efficient charging infrastructure becomes increasingly critical. Wireless charging technology presents a promising solution to address the limitations of traditional plug-in charging systems, offering convenience and flexibility to EV users. This Project explores the concept of wireless EV charging while the vehicle is in motion, also known as dynamic wirelesscharging (DWC). By integrating inductive power transfer (IPT) technology with dynamic charging infrastructure embedded in roadways or dedicated lanes, vehicles can replenish their batteries continuously while in motion, extending their range and reducing the need for frequent stops. Furthermore, DWC has the potential to enhance the feasibility and adoption of EVs in various sectors, including public transportation, logistics, and personal mobility. This abstract provides a comprehensive overview of the emerging field of wireless EV charging while the vehicle is inmotion, highlighting its benefits, challenges, and future prospects.

An Improved Voltage Control Method for EAST Fast Control Power Supply

The Experimental Advanced Superconducting Tokamak (EAST) fast control power supply (FCPS) is an important device for controlling the vertical displacement of plasma during the nuclear fusion power generation process, adopting a multiple H-bridge invertor branch parallel operation structure to output total current. At the beginning of each shot of plasma discharge, FCPS works in open-loop voltage control mode (VCM) or closed-loop current control mode (CCM) determined by the plasma control system to output current for exciting the load coil, to achieve plasma vertical displacement control. VCM has the characteristics of fast dynamic response speed but poor consistency of branch current and insufficient branch current control accuracy and stability because of open-loop control. CCM has the characteristics of high branch current control accuracy but poor dynamic response and robustness because of control delay and control parameters determined based on engineering experience. To achieve fast and robust control, an improved voltage control method (IVCM) is proposed by combining the advantages of VCM and CCM. In the beginning of establishing the output current, FCPS operates in VCM, and rapid establishment of the output current is ensured. After the output current rapidly increases to the critical value, closed-loop current control is added to VCM to ensure the accuracy of output current control. In closed-loop current control, linear super-twisting sliding mode control is designed to achieve fast and robust control, ensuring good consistency and fast dynamic response performance of each branch current. Simulations and experiments verify that the designed IVCM has better compatibility characteristics in output current stability, control accuracy, and consistency of each branch current compared to VCM.

Optimization of the Repeating Coil in Three-Coil WPT System

This paper examines the optimal conditions for the three-coil Wireless Power Transmission (WPT) system. Initially, an equivalent circuit model was developed Experiments were conducted to explore the impact of the repeating coil parameters and load resistance on the three-coil WPT system. We determined the optimal distance between the transmitting coil and the repeating resonator under various parameters of repeating coil turns, as well as different load resistance, to maximize the system's overall transmission efficiency. It indicates that in the three-coil WPT system, the optimal distance between the transmitting and repeating coils is directly proportional to the load resistance. Moreover, when the turns of the transmitting, repeating, and receiving coils are fixed at seven, the optimal distance changes slightly as the number of turns of the repeating coil increases, but changes significantly when the number of turns decreases. Additionally, when the change in load is constant, an increase in the radius of the repeating coil results in a greater change in the optimal distance. These findings provide important reference information for optimizing the efficiency of triple-coil WPT systems.

Optimal Design of Relay Coil Inductance to Improve Transmission Efficiency of Four-Coil Magnetic Resonance Wireless Power Transmission Systems

Magnetic resonance wireless power transmission consists of a source coil and relay coil (transmission coil (Tx-coil), receiving coil (Rx-coil)). The relay coil is designed with windings and a series capacitor, which are resonant with the input voltage frequency. Magnetic resonant wireless power transmission by a relay coil enables the transmission of power from a few centimeters to several meters. Recently, research has been conducted on the shape and material of each coil to increase the transmission distance. However, limitations remain with respect to increasing the transmission distance. Specifically, the optimization of the electrical characteristics of the relay coil is necessary to increase the transmission distance and improve efficiency. In this study, we configured the inductance of the relay coil to be approximately 95 μH, 270 μH, and 630 μH. Accordingly, we designed the series capacitors to have the same resonant frequency and analyzed the transmission characteristics of each relay coil. We confirmed that as the inductance increased, the transmission efficiency increased by up to 10%. The relay coil was designed to have an inductance of approximately three to six times that of the source coil (load coil). Thus, the optimal design of the relay coil is believed to be the most efficient and economical coil design.

Response surface optimization design of flexible positioning platform considering its fatigue life

The research of macro and micro motion platforms has always been committed to realizing the ultra-high acceleration operation of the platform and improving the positioning accuracy of the platform. With the goal of achieving ultra-high-speed, the impact of the increase in speed on key components has also attracted more and more attention. This paper takes a flexible positioning platform of an ultra-high acceleration macro–micro motion platform with adjustable voice coil motor (VCM) number and load as the research object. Perform static analysis, rigid-flexible coupled dynamic analysis, fatigue analysis, and multi-objective response surface optimization design (RSMD). The influence on the acceleration of the platform and the influence on the stress and fatigue life of the flexible positioning platform with the change of the number and load of the VCM were explored. The changes of the acceleration and speed curves of the platform during ultra-high-speed operation are obtained by dynamic analysis, and the position of the dangerous part of the flexible platform during operation is obtained. Finally, the RSMD is carried out to realize its performance optimization. The research conclusions of this paper have great reference value for the development of the macro–micro motion platform and the improvement of its structure.

Analysis and Design of High-Frequency WPT System Using Load-Independent Inverter With Robustness Against Load Variations and Coil Misalignment

Analysis and Design of High-Frequency WPT System Using Load-Independent Inverter With Robustness Against Load Variations and Coil Misalignment

Multi-resonator Wireless Inductive Power Link for Wearables on the 2D Surface and Implants in 3D Space of the Human Body.

This paper presents a novel resonance-based, adaptable, and flexible inductive wireless power transmission (WPT) link for powering implantable and wearable devices throughout the human body. The proposed design provides a comprehensive solution for wirelessly delivering power, sub-micro to hundreds of milliwatts, to deep-tissue implantable devices (3D space of human body) and surface-level wearable devices (2D surface of human skin) safely and seamlessly. The link comprises a belt-fitted transmitter (Belt-Tx) coil equipped with a power amplifier (PA) and a data demodulator unit, two resonator clusters (to cover upper-body and lower-body), and a receiver (Rx) unit that consists of Rx load and resonator coils, rectifier, microcontroller, and data modulator units for implementing a closed-loop power control (CLPC) mechanism. All coils are tuned at 13.56 MHz, Federal Communications Commission (FCC)-approved industrial, scientific, and medical (ISM) band. Novel customizable configurations of resonators in the clusters, parallel for implantable devices and cross-parallel for wearable devices and vertically oriented implants, ensure uniform power delivered to the load, PDL, enabling natural Tx power localization toward the Rx unit. The proposed design is modeled, simulated, and optimized using ANSYS HFSS software. The Specific Absorption Rate (SAR) is calculated under 1.5 W/kg, indicating the design's safety for the human body. The proposed link is implemented, and its performance is characterized. For both the parallel cluster (implant) and cross-parallel cluster (wearable) scenarios, the measured results indicate: 1) an upper-body PDL exceeding 350 mW with a Power Transfer Efficiency (PTE) reaching 25%, and 2) a lower-body PDL surpassing 360 mW with a PTE of up to 20%, while covering up to 92% of the human body.

Disturbance supression improved discrete sliding mode fast current tracking control of experimental advanced superconducting tokamak fast control power supply

SummaryThe output current of the fast control power supply for the Experimental Advanced Superconducting Tokamak (EAST) excites the load coil. Magnetic field can be quickly generated by the fast output current to control the balance of plasma vertical displacement. In order to improve the output current speed of EAST fast control power supply and its ability to resist external disturbance, an improved discrete integral sliding mode control method combining gray prediction and variable gain sliding mode observer is proposed. A sliding mode disturbance observer is used to observe the total disturbance on the load side, and feedforward compensation control is performed on the total disturbance. To further suppress chattering and accelerate convergence speed, a high‐order term is added to the traditional discrete exponential reach law, and a gain adaptive observer is designed to adaptively adjust the observer gain based on the observed current error and the tracking current error. In the current sampling process, an improved gray prediction structure is added, and the original current sequence of gray prediction is improved based on the principle of new information priority, improving the accuracy of predicted current, compensating for the inherent delay in digital control, and further improving the output current response speed. Simulation and experimental verification show that the proposed disturbance suppression improved discrete integral sliding mode fast current tracking control strategy has faster output current response speed and strong antidisturbance performance.

Equivalent Circuits of Dipole Antennas for Broadband Applications

In this paper distributed parameter equivalent circuits are developed for linear dipoles, dielectric coated dipoles and lumped loaded dipoles. Theoretical solutions for each distributed parameter and the reasonable non-uniform segmentation of antennas serve as the foundation for the derivation. The accomplished validations of the modeling procedures indicate that the given equivalent circuits are capable of correctly describing dipole antennas in frequency and time domains, with the advantages of wideband, frequency independence and unambiguous physical meaning. Relying on the presented equivalent circuits, broadband issues such as simulating input impedance, predicting equivalent lengths and computing transient responses of dipole antennas can be readily addressed. In addition, the circuit model provides helpful insights into the analysis and design for the loaded dipole antennas.

Mg‐Zn Ferrite Nanoparticles: A Brief Review on Synthesis, Characterizations, and Applications

AbstractFerrites are of great interest for both fundamental science and technological applications due to their outstanding physical, chemical, and magnetic properties. Among various ferrites, Mg‐Zn ferrites is one of the best magnetic materials for researchers due to their unique properties such as high electric resistivity, Curie temperature, low coercivity, low eddy current, dielectric losses, low cost, and better environmental stability. This makes ferrites suitable for many applications such as power transformers, microwave devices, computer memories, logic devices, recording heads, loading coils, antenna rods, color monitoring tubes, telecommunications, hyperthermia, and so forth. Mg‐Zn ferrite nanoparticles have gained increased interest for many applications such as catalysts, antimicrobial potential, and sensors for the detection of combustible gases (CH4, CO, and CO2). In this brief review, the strategies used in the synthesis of Mg‐Zn ferrite nanoparticles are summarized. The different structural, morphological, magnetic, and electric properties of these ferrites are analyzed.

Physics-informed hierarchical data-driven predictive control for building HVAC systems to achieve energy and health nexus

Buildings consume 74% of US electricity and 40% of primary energy use. However, 15% of the energy was wasted due to bad controls. Many research studies have demonstrated that model predictive control strategies could provide significant energy savings, but the lack of a scalable building dynamic model impeded the large-scale implementation of predictive control strategies. Moreover, many predictive control strategies lacked the consideration of indoor air quality. Therefore, in this research study, we proposed a novel physics-informed input convex neural network (PINN) to predict indoor environmental dynamics with 6 h ahead. The model sanity check results showed that the proposed PINN had physically consistent behavior to different control inputs. Then, the PINN is used to design a hierarchical data-driven predictive control (HDDPC) strategy to minimize both the space cooling load and airside coil load. Three different case studies were simulated to evaluate the proposed control strategy comprehensively: a) maintaining a similar indoor temperature profile as the measurement to evaluate energy reduction potential by the HDDPC; b) evaluating the impact of the proposed weather forecast models on the HDDPC performance by comparing the case with perfectly accurate weather information and the case with forecasted weather information. Results indicated that the hierarchical data-driven predictive control strategy with weather forecasting had a similar performance with measured weather inputs. On average, the HDDPC strategy could reduce more than 35% of total cooling energy and 70% of total airside coil energy with the guarantee of indoor thermal comfort and air quality.

Electromagnetic Displacement Sensor and Docking Method Based on Elliptic Integral Series Expansion

Automatic charging can improve the endurance of unmanned work platforms, but the docking accuracy limits its success rate and charging efficiency. In order to solve this problem, an accurate docking method based on elliptic integral series expansion is proposed. The relationship between load voltage and coil transverse offset distance is constructed by establishing a coil mutual inductance circuit, a coil center points transverse offset mutual inductance coefficient calculation model, and a triangular positioning geometry structure Numerical integration and elliptic integration series expansion are used to solve the exact correspondence between the coil mutual inductance coefficient and the coil transverse offset distance. Finally, the relationship between the load voltage and the lateral offset distance from the center of the coil is obtained. The method does not require the arrangement of additional sensors and coils, nor does it require extensive prior data collection for unique coil configurations. The system can be used for energy transmission and as a displacement sensor. It has been verified by COMSOL simulations that the maximum relative error in the coefficient of mutual inductance is 6.507% for the numerical integration method and 9.022% for the elliptic integration series expansion approach. After experimental verification, the maximum average relative error of the load voltage is 4.048% for the numerical integration method and 11.89% for the elliptic integration series expansion approach. This method achieved high accuracy positioning measurement with the error range at the centimeter level. The method contributes to the long-term application of unmanned operating platforms.

Primary Multi-Frequency Constant-Current Compensation for One-to-Multiple Wireless Power Transfer

One-to-multiple wireless power transfer (O2M-WPT) is convenient and flexible, using a single transmitter to power multiple loads. However, existing O2M-WPT still exhibits several drawbacks: 1) the primary coil tends to burn out when there is a load open circuit or coils misalignment; 2) the compensation network cannot naturally realize constant-current (CC) or constant voltage (CV) output. In this paper, a primary multi-frequency constant-current compensation (MFCC) network is proposed to solve these problems. With the MFCC, the primary side works as a current source at multiple operating frequencies, and the receivers can achieve CC or CV output, meeting the requirements of various loads. Experimental results verify the effectiveness of the proposed MFCC network for the O2M-WPT systems.

Effective circuit modelling and experimental realization of an ultra-compact self-rectifier flux pump

This paper presents experimental and modelling results of an ultra-compact self-rectifier flux pump (FP) energizing a superconducting coil. The device fits inside a volume of mm and generates up to 320 A dc through the coil and a peak output voltage up to 60 mV. We also develop and present a full electromagnetic effective circuit model of the FP and compare its predictions to the experimental results. We show that our model can reproduce accurately the charging of the load coil and that it reproduces the systematic dependence of the maximum load coil current on the input current waveform. The experiments and modelling together show also the importance of dc-flux offsets in the transformer core on the final achievable current through the coil. The miniaturization possible for this class of FP and their minimal heat-leak into the cryogenic environment from thermal conduction make them attractive for applications with demanding size, weight and power limitations. Our effective circuit model is a useful tool in the understanding, design and optimization of such FPs which will accelerate their progression from research devices to their application.

Research on the cooperative control strategy of output current in a distributed generation system

In the ship degaussing system, a distributed power system is adopted, in which a single power module drives an independent coil load respectively. To ensure the degaussing effect, it is necessary to ensure the dynamic and static integrity of the load current. If an appropriate cooperative control strategy is not designed, the dynamic consistency of output current will be greatly affected by the difference in load. Therefore, this paper designs the cooperative control strategy based on the multi-agent consistency theory and proves the stability and consistency of the control strategy through the theory of discrete state space equation and graph theory. Through the simulation and experiment of multi distributed power system, it is verified that the control strategy has a good effect on improving the output current consistency of the power system.

Demonstration of ITER Real-Time Framework with application of PF coil control in KSTAR

ITER Real-Time Framework (RTF) is a middleware for developing fast real-time control applications such as plasma control system (PCS). In this framework, applications are built by creating and assembling Function Blocks (FBs) as atomic components of the application. The RTF can easily configure the application to be operated with multi-thread, multi-process, or multi-node processing under real-time mode. In this paper, we demonstrated capability of the RTF on the Poloidal Field (PF) coil Magnetic Power Supply (MPS) system of KSTAR. First, we fully implemented the KSTAR PF coil control logic from the KSTAR PCS into an independent RTF application. By configuring the real-time mode and multi-thread processing, 11 PF coils can be simultaneously controlled with a 20 KHz execution cycle. Second, we applied a built-in exception handler in the RTF to implementing protection from specified off-normal events such as PF Power Supply Fault (PSF) and PF OverCurrent Fault (OCF). Third, we integrated the standard real-time network interfaces of the KSTAR, the Reflective Memory (RFM) network, with the RTF application. Finally, we made a shot automation interface in order to run the RTF application according to the KSTAR shot sequence stages. This interface also has a snapshot functionality to store and load all experimental parameters for each shot number. We evaluated the effectiveness of the RTF application through a single PF MPS test connected with a 40 mH dummy load coil.

Control strategy for the magnetic energy storage and transfer system (MEST)

The Magnetic Energy Storage and Transfer system (MEST) aims at improving the power handling in supplying the SuperConducting (SC) coils of fusion experiments. It is based on smart use of Superconducting Magnetic Energy Storage technology and allows the introduction of a certain degree of decoupling between the grid and the load. The MEST operation is based on the storage and transfer of the needed energy between the Load Coil (LC) and an additional storage inductor named Sink Coil (KC); the energy transfer is realized via capacitors switched by fully controllable semiconductors.This paper focuses on the control system of the MEST and proposes a control strategy, based on two decoupled control loops, with the aim both to guarantee the desired current on the load coil and the compensation of the system losses. A model of the MEST with the proposed control system has been developed to analyze the performance through numerical simulations. The control strategy and the simulation results will be presented and discussed in the paper.

Miniaturized double transit magnetic field measurement probe using the Faraday rotation principle.

This paper presents the design and experimental results of a double transit magnetic field measurement probe based on the Faraday rotation principle using terbium doped borosilicate glass as a sensor element. When the magnetic field is applied in the direction of propagation of light through the glass, the Faraday effect produces non-reciprocal circular birefringence. This property of the Faraday effect adds rotations when the light beam is reflected using a mirror placed at the other end of the glass and passed through the glass, making double transit of light through the sensor element. Experiments were carried out to verify the characteristics of the designed probe by inserting it inside the solenoid load coil. The Verdet constant of the glass is determined using the slope of the linear least-squares fitted curve between the Faraday rotation angle and the applied magnetic field, obtained as 89.22r a d/(T⋅m) with a relative uncertainty of 2.43%. The magnetic field was measured with 0.28% accuracy. In the optics experiments, alignment of components is the major task. To the authors' knowledge, this is the first of its kind double transit miniaturized magnetic field measurement probe configuration in which components are aligned inside the single probe structure. The probe is easily portable and can be used in inaccessible locations in various applications such as accelerators, Z/θ pinch devices, or fusion reactors such as tokamaks, in which the magnetic field is one of the main parameters.

PANDEMIC: Occupancy driven predictive ventilation control to minimize energy consumption and infection risk

During the SARS-CoV-2 (COVID-19) pandemic, governments around the world have formulated policies requiring ventilation systems to operate at a higher outdoor fresh air flow rate for a sufficient time, which has led to a sharp increase in building energy consumption. Therefore, it is necessary to identify an energy-efficient ventilation strategy to reduce the risk of infection. In this study, we developed an occupant-number-based model predictive control (OBMPC) algorithm for building ventilation systems. First, we collected the occupancy and Heating, ventilation, and air conditioning system (HVAC) data from March to July 2021. Then, four different models (Auto regression moving average-based multilayer perceptron (ARMA_MLP), Recurrent neural networks (RNN), Long short-term memory networks (LSTM), and Nonhomogeneous Markov with change points detection (NH_Markov)) were used to predict the number of room occupants from 15 min to 24 h ahead with an interval output. We found that each model could predict the number of occupants with 85 % accuracy using a one-person offset. The accuracy of 15 min of the ahead prediction could reach 95 % with a one-person offset, but none of them could track abrupt changes. The occupancy prediction results were used to calculate the ventilation demand using the Wells-Riley equation, and the upper bound can maintain an infection risk lower than 2 % for 93 % of the day. This OBMPC model could reduce the coil load by 52.44 % and shift the peak load by 3 h up to 5 kW compared with 24 × 7 h full outdoor air (OA) system when people wear masks in the space. The occupancy prediction uncertainty could cause a 9 % to 26 % difference in demand ventilation, a 0.3 °C to 2.4 °C difference in zone temperature, a 28.5 % to 44.5 % difference in outdoor airflow rate, and a 10.7 % to 28.2 % difference in coil load.