Power Transmission Method Research Articles

Wireless power transmission using a resonant coil consisting of conductive yarn for wearable devices

This paper presents a wireless power transmission method that uses magnetic resonant coupling with resonant coils made of conductive yarn that can be integrated into clothing. The conductive yarn consisted of silver-plated copper and polyester filaments. The transmission characteristics of the yarn and copper resonant coils were compared using simulation and measurement tools. It was determined that the signal loss of the conductive yarn resonant coils was higher than that of the copper coils. However, the increase in the signal loss variation was less than 1 dB when the transmission distance was less than 6.5 cm. The conductive yarn resonant coils were placed in the shoes and trouser cuffs of a human subject, and the transmission efficiency was measured after the received alternating current power was converted to direct current power using an alternating current–direct current converter. The measurement results showed a maximum transmission efficiency of 50%; the average transmission efficiency was 45%, despite the change in the coil shape and alignment conditions due to body movement. In addition, the results demonstrated an excellent transmission efficiency of over 40% when the subject was moving at a speed of 6 km/h. It was also shown that the textile coils can be an integrative solution, overcoming clothing comfort and continuous power supply for a new generation of wearable devices.

An Improved Design Method of High Efficiency Contactless Power Transmission in Ultrasonic Vibration System

To improve the efficiency of contactless power transmission (CPT) and the operation stability of ultrasonic vibration system, an improved design method for key parts of the contactless power transmission system was proposed and studied. By integrating both inductor model and mutual inductance model, as well as considering the fringing flux effect introduced by the air gap, this design method would be more accurate and reasonable. Considering constraint conditions, such as the operating flux density of the core, mutual inductance between primary and secondary coils, electrical signals loaded on ultrasonic vibrator, the coils and cores were designed. Simulation and experimental studies which were developed on flux density, mutual inductance and amplitude output ability of the system, verified that the key parts of CPT system could stay stable during operation and the CPT system was able to transfer ultrasonic energy efficiently.

Joint Optimization for Optimal Power Allocation in OFDMA Femtocell Networks

This letter is concerned with the optimal power allocation in femtocell networks using a new technique based on multiobjective optimization. In this letter, we consider a cochannel framework for the coexistence of orthogonal frequency division multiple access (OFDMA)-based macrocell and femtocell networks. We jointly maximize the total rate of OFDMA femtocell network and minimize the total transmit power of femtocell base stations while satisfying a target constraint on transmit power when either the cross femtocell interference is included or excluded. Additionally, the results show that the proposed method for power transmission contributes toward improving the energy efficiency of femtocell networks.

Time-Modulation of Linear Arrays for Real-Time Reconfigurable Wireless Power Transmission

This paper proposes a smart wireless power transmission method, based on a two-step procedure, exploiting real-time beaming of time-modulated arrays. The sideband radiation phenomenon, which is usually a drawback of these radiating systems, is favorably used for intentional wireless power transfer (WPT): in a first step to precisely localize the tag to be powered and in the second one to perform directive WPT. The approach is first theoretically discussed, then the numerical procedure, which integrates full-wave analysis of the antenna array with nonlinear simulation of the modulated nonlinear feeding network, is used to validate the principle of operation and to include nonlinearities and electromagnetic couplings affecting the whole system performance. The procedure allows a flexible design of the time-modulated-array-based WPT system, taking into account the impact of different array elements layout and spacing on localization and power transmission performance. Experiment of the first step is carried out in a real indoor environment at 2.45 GHz: a TI MSP430 drives a Schottky-diode-based network to provide proper modulated RF excitations of the array elements. Measurements show that the system is able to select tags to be energized randomly distributed in a 100 $^{\circ}$ -scanning range.

Определение формы провода ЛЭП на основании вычисления по геодезическим измерениям функции ее аппроксимирующей

Abstract: Power line is a complex engineering structure, serving for power transmission from a distance. Nowadays this method of power transmission is the most financially justified for part of the cost in comparison with cable gaskets. Thereby power lines shrouded the city, as well as interconnected. And in recent years existing support are used for suspension lines (Fiber-optic transmission line). For the implementation of the suspension cable is necessary to know the existing slack wire. This article provides a rationale computation capabilities of wire marks in any migration or all of the anchor spans phase high voltage transmission lines on the measured elevations of the wire in one of the spans of the anchor section. This methodology is maximally reduced to a simple implementation method, without complex calculations, so it may be useful to professionals working in the field of research and design of power lines facing in practical activities with the need for rapid results.

A novel hydraulic-mechanical hybrid transmission in tidal current turbines

Tidal current energy is a promising renewable energy, and it has become a research hotspot all over the world. Tidal current turbines (TCTs) are the devices that capture tidal current energy and convert it into electricity. Power train is one of the key technologies, and a gearbox is traditionally used. Because of the disadvantages of the gearbox, several soft power transmission methods have been studied, such as hydraulic power train and direct-drive train. Aiming for maximum power point tracking (MPPT) and constant frequency simultaneously, this paper introduces the hydraulic-mechanical hybrid transmission for TCT. Different from the traditional mechanical transmission, the hydraulic-mechanical hybrid transmission uses a two-degree-of-freedom planetary gear (TDPG) as the power split device. In this transmission, the rotor speed can be regulated by hydraulic pump displacement control to realize the MPPT, and the power can be stabilized through the hydraulic system. In this paper, the hydraulic-mechanical hybrid transmission is introduced, and the characteristics of the TDPG are analyzed first. Then, the control strategy of TCT is proposed. Finally, the system is modeled and constructed, and the simulation results confirm the validity of the hydraulic-mechanical hybrid transmission of TCT.

Smart Wireless Power Transfer Operated by Time-Modulated Arrays via a Two-Step Procedure

The paper introduces a novel method for agile and precise wireless power transmission operated by a time-modulated array. The unique, almost real-time reconfiguration capability of these arrays is fully exploited by a two-step procedure: first, a two-element time-modulated subarray is used for localization of tagged sensors to be energized; the entire 16-element TMA then provides the power to the detected tags, by exploiting the fundamental and first-sideband harmonic radiation. An investigation on the best array architecture is carried out, showing the importance of the adopted nonlinear/full-wave computer-aided-design platform. Very promising simulated energy transfer performance of the entire nonlinear radiating system is demonstrated.

AC–AC Converter With Controllable Phase and Amplitude

By adopting the concept of virtual quadrature source (VQS), a novel method for power transmission control-ac-ac converter with controllable phase and amplitude (ACCPA) was proposed, which has two control variables and is able to continuously regulate the phase and the amplitude of its output voltage independently. The operation principle was studied in detail, and the relationship with the optimization of control parameters of ACCPA's two duty ratios was analyzed for regulating the phase and amplitude of its output voltage. The phase is regulated in the front part, and the amplitude is regulated in the back part. For phase regulation, two methods were proposed to select optimal control parameters dynamically. The curves followed by two methods are crossed at the reference phase angle and have the same initial control parameters. It is necessary to adjust two independent control parameters for method 1 and one parameter for method 2. So method 2 is simple, easy to implement and has high control stability in comparison with method 1. The control strategy of ACCPA was presented and a prototype of single-phase ACCPA was manufactured. The experimental results verified the correctness of the theory and the feasibility of the control strategy.

An Optimization and Planning Method Research to Determine Power Transmission Capacity of Clustering Wind Farms Accounting Risk

Large-scale wind farms connected into main grid is accompanied by the reducing of the stability, reliability and security of the power system operation. So the risk cost becomes one of the important factors influencing the profit of transmission network expansion planning. This paper adopted the method of clustering wind power transmission. The objective function established in this paper reflecting the comprehensive benefits of transmission project defined the Pline (transmission capacity) as variable. In order to maximize the comprehensive benefits of the transmission project, the influence of transmission constructing cost, the congestion loss probably caused by a low transmission capacity as well as the cost of risk were taken into account. Calculation of risk is a very complex mixed integer nonlinear problem, so we used Monte-Carlo Simulation to solve this question. Example shoes that the proposed method can achieve optimal transmission capacity, transmission project benefit and planning.

Field Distribution Models of Spiral Coil for Misalignment Analysis in Wireless Power Transfer Systems

This paper presents design and optimization methods for spiral coils utilized for wireless power transfer in wireless medical implant applications. A theoretical model was examined for near-field distributions of spiral-type transmitter antennas in both orthogonal components. Finite-element simulations were performed to verify the theoretical radiation patterns. Receiver antenna voltages were measured at planes of interest as a means to map field distributions. Theoretical, simulation, and experimental results were conducted in free space and they agreed well. Understanding the orthogonal field components and their distributions in various distances between the worn transmitter coil outside the body and the receiver coil of implant that has a much smaller size provides a means to find the optimal location and angle to harvest maximum energy. The analysis method for near-field wireless power transmission can be utilized to determine design strategies of the transmitter spiral coil with considerations also in the amplifier circuit and physical constraints in practical scenarios to obtain maximum power and link efficiency for the implant devices. The method can be extended to investigate field distributions affected by human tissues, which construct a much more complex environment, and will be conducted in future works.

Multi-Attribute Comprehensive Evaluation Method for Power Transmission and Transformation Projects

With the number of power transmission and transformation projects increasing, it needs to consider more indices information and utilize more comprehensive evaluation methods in the decision-making of building schemes. As a consequence, a comprehensive evaluation indices system, including the indices of network security, economy, environmental friendliness, adaptation and coordination of the power transmission and transformation engineering system, is firstly built to evaluation construction schemes. Then this paper proposes a multi-attribute comprehensive evaluation method for power transmission and transformation projects. In this method, the optimal combination weighting method based on the moment estimation is adopted to weight for every index. It can overcome the weakness of the subjective weighting methods and the objective methods. After that, the optimal scheme is obtained by the grey correlation-cosine prioritizing evaluation method, which can take into account the distance and angle information of schemes. Finally, the example shows this method can fully consider overall information of each index, having good operability.

Single-contact transmission for the quasi-wireless delivery of power over large surfaces

A method of power transmission is proposed that delivers power through the resonance of a helical receiver with its surrounding stray capacitance. The system operates in a quasi-wireless state where power is transferred over a single connection to a surface much larger than the dimensions of the receiver. This ensures high-efficiency energy transfer over large areas without the need of strong coupling electromagnetic fields. Standard power connectors such as tracks, plugs, and cords may be easily replaced with conductive surfaces or objects such as foil sheets, desks, and cabinets. Presently, the method is experimentally demonstrated at the small scale using loads of up to 50 W at an efficiency of 83% with both bare and insulated surfaces. Simple circuit modeling of the system is presented which shows close agreement with experimental results.

Multiple-Way 1-Wire Transmission System Design

In this paper, a new 1-wire transmission system for the host-slave communication is introduced, which is composed of STM32 embedded host system, CPLD logic control system and PIC slave system. The transmission line is not only for data transmission between host and 32-way slave, but also for power supply for 32-way slave. This paper details the hardware and software implementation method of each component module based on the given system function, and highlights the circuit design method of power and signal transmission on the same line in the 1-wire transmission system. Experiment results are shown in the final chapter.

Smart wireless sensing and assessment for civil infrastructure

Recently, there has been increasing need for adopting smart sensing technologies to structural health monitoring (SHM) applications for civil infrastructure. In this paper, the state of the art in smart wireless sensing and assessment techniques for civil structures are reviewed focusing on full-scale applications. Three types of smart wireless sensing technologies are discussed: wireless acceleration sensor-based SHM, wireless impedance-based SHM and an optics-based non-contact actuation and sensing technique. At first, vibration-based SHM using a dense array of wireless acceleration sensors is implemented to a cable-stayed bridge. The modal identification of the bridge and cable tension estimation are carried out using the ambient acceleration data. Measured data during a typhoon is also discussed. Secondly, impedance-based SHM using piezoelectric active sensors is presented focusing on hardware and software issues. A wireless impedance sensor node is presented for local SHM and neural network-based smart assessment algorithm is proposed to detect multi-type damages. Finally, a wireless power and data transmission method using laser and optoelectronic technologies is presented for non-contact measurement of guided waves and impedance, and subsequent damage detection. This method is embodied in a small printed circuit board, and the performance is validated on a lab-scale steel truss member.

Contactless power and data transmission for underwater sensor nodes

When the technology of wireless sensor network is applied to ocean monitoring, the ocean underwater monitoring system will become a distributed network system. That could improve the level of ocean monitoring significantly. But most of the current ocean monitoring equipments work independently, and it is difficult to form them into a sensor network. To set up a sensor network, electric energy supply and data transmission are the chief problem, especially for the underwater sensor nodes. To solve this problem, a new method for contactless power and data transmission is proposed. It operates with the principle of electromagnetic coupling. Power and data are transmitted through a mutual channel. This channel is realized by the structure of a two-stage electromagnetic coupler. Here, steel rope is used as the closed steel ring to compose an electromagnetic coupler. Since steel rope is widely used in the current underwater equipments, the transmission channel of power and data can be realized without changing the existing structure. Furthermore, because of contactless transmission the sensor network has good expansibility and convenient configuration of its nodes for underwater applications. A voltage transformation model for the two-stage electromagnetic coupler is constructed and the transmitting principle of power and data is analyzed based on the model. According to the energy transmission efficiency and the bit error rate, an experimental prototype is designed and fabricated. Finally, the prototype testing of power transmission, data transmission, and reactive power compensation are carried out. The experimental results show that the proposed method for contactless power and data transmission is feasible and it is suitable for the application of underwater sensor nodes.

Study of Channel Characteristics for Galvanic-Type Intra-Body Communication Based on a Transfer Function from a Quasi-Static Field Model

Intra-Body Communication (IBC), which modulates ionic currents over the human body as the communication medium, offers a low power and reliable signal transmission method for information exchange across the body. This paper first briefly reviews the quasi-static electromagnetic (EM) field modeling for a galvanic-type IBC human limb operating below 1 MHz and obtains the corresponding transfer function with correction factor using minimum mean square error (MMSE) technique. Then, the IBC channel characteristics are studied through the comparison between theoretical calculations via this transfer function and experimental measurements in both frequency domain and time domain. High pass characteristics are obtained in the channel gain analysis versus different transmission distances. In addition, harmonic distortions are analyzed in both baseband and passband transmissions for square input waves. The experimental results are consistent with the calculation results from the transfer function with correction factor. Furthermore, we also explore both theoretical and simulation results for the bit-error-rate (BER) performance of several common modulation schemes in the IBC system with a carrier frequency of 500 kHz. It is found that the theoretical results are in good agreement with the simulation results.

Modeling of Transcutaneous Inductive Power Transmission

The results of this work are discussed in the context of theoretical research into different wireless power and data transmission methods, subject to a specific environment, such as bioimplantable devices. According to this study, the optimal wireless power transmission method is inductive; optimal power transmission frequency range is 0.1–1 MHz. A mathematical model of transcutaneous wireless power transmission system and a tool for its design are suggested.

Optimum Design of Rotary Non-Contact Electric Power Transmission Device for Ultrasonic Vibration Internal Grinding System

Through theoretical analysis and simulation, a practical structural and design method of rotary non-contact electric power transmission (RNEPT) device for ultrasonic vibration internal grinding (UVG) system were proposed, experiments about the prototype of the RNEPT device for UVG system were studied, the feasibility of the optimum design methods was verified.

A method for improving the wireless power transmission efficiency of an endoscopic capsule based on electromagnetic localization and synthesis of magnetic field vector

The method of wireless power transmission is an important method in powering wireless medical devices in vivo, but the efficiency is still low, especially when the devices move freely in random positions and orientations. Aiming at powering an endoscopic capsule, a method for improving efficiency of wireless power transmission is proposed, which is based on electromagnetic localization and synthesis of magnetic field vector. By analysing the model and experimenting in vitro, the proposed method is verified, which can improve the efficiency of the wireless power transmission because of accurate localization of the capsule and synthesis of magnetic field vector.

Design and Characterization of a Novel Hybrid Actuator Using Shape Memory Alloy and DC Micromotor for Minimally Invasive Surgery Applications

The end-effectors in the state-of-the-art robotic tools for minimally invasive surgery (MIS) are actuated by actuator packs located outside the patient's body, with the power transmitted from the actuator pack to the end-effector by means of sliding link or tendon-driven mechanisms. This method of power transmission limits the number of degrees-of-freedom (DOFs) in these systems, as the design of a spherical wrist gets complicated. The design of the spherical wrists can be simplified, and the number of DOFs increased, if local actuation is used for the end-effector. However, there are no suitable actuation systems available in the literature. In this paper, a novel design idea for developing a millimeter-scale actuator is presented for locally actuating the end-effector (5-mm-diameter laparoscopic needle driver) for a robot performing MIS. This actuator is designed by combining a dc micromotor and a shape memory alloy actuator in series. The designed actuator is 5.14 mm in diameter (including casing) and 40 mm in length, and is used to actuate a 20-mm-long needle driver assembly, while generating a force of 24 N, resulting in a gripping force of 8 N. The total stroke length of the actuator is 1 mm, which results in a 45 opening of the needle driver jaw with a gap of 8 mm in between the jaws.