Maximum Power transfer (original) (raw)
A general maximum power transfer theorem
IEEE Transactions on Education, 1995
This paper reviews the conventional maximum power transfer theorem and presents a modification to the theorem by incorporating a measure of the relative importance of power transmission efficiency over power transferred to the load.
Maximum power transfer in non-linear source-load systems
International Journal of Circuit Theory and Applications, 1984
This paper is concerned with the conceptual design and realization of matching networks for the continuous transfer of maximum power from a non-linear source with randomly varying characteristics to a load. Such sources are commonly encountered in the use of photovoltaic arrays or wind energy conversion systems for the production of electric power. Experimental studies as well as computer simulation results verify the validity of the design and point to methods for its practical implementation.
Maximum Power Transfer versus Efficiency in Mid-Range Wireless Power Transfer Systems
Journal of Microwaves, Optoelectronics and Electromagnetic Applications, 2015
The condition for maximum power transfer of 2-coils wireless power transfer (WPT) system is derived from circuit analysis and discussed together with the respective WPT system efficiency (η). In the sequence, it is shown that a 4-coils WPT system (which can be divided in source, two communication and load circuits) without power losses at the two communication circuits (ideal 4-coils WPT system) presents, from maximum power transfer and efficiency point of view, a performance similar to those of a 2-coils WPT system. The exception is the influence of coupling coefficient (k): in 2-coils system η increases as k approaches one, while in ideal 4-coils WPT system η increases as k between the two communication coils approaches zero. In addition, realistic 4-coils WPT systems (with power losses at the two communication circuits) are also analyzed showing, for instance, that η presents a maximum as a function of k of the communication coils. In order to validate the presented theory, 4 coils were built, and a setup to perform 2coils and 4-coils WPT systems has been carried out. Practical results show good agreement with the developed theory. Index Terms-Maximum power transfer, power transfer efficiency, relative power transfer, wireless power transfer. I. INTRODUCTION Wireless power transfer (WPT) technology has been widely discussed in the last years [1-6]. For instance, in a recent article the progress in mid-range WPT systems has been critically reviewed discussing, among other topics, the importance of maximum power transfer (MPT) condition and power transfer efficiency (η) in the design of these circuits [1]. However, a specific derivation of MPT condition of WPT systems, from which their η could be properly addressed, was not presented. The aim of this paper is to present the derivation of MPT conditions for 2-coils and 4-coils WPT. Based on the derived MPT conditions, the systems efficiencies are discussed. The strategy adopted in this work to show that the method used to derive the mentioned conditions is correct was to compare its results, whenever possible, with classical MPT theorem conclusions. In this way, it is demonstrated that the theoretical and practical results correspondent to 2-coils and theoretical result related to ideal 4-coils WPT (without power losses at the two communication circuits) systems are coherent with classical MPT theorem conclusions. Of course, the real systems (with losses at communication coils) differ from the ideal circuits, showing a maximum in the efficiency curve. Practical experimentations
Analysis and Optimization of an Inductive Power Transfer With a Randomized Method
IEEE Transactions on Instrumentation and Measurement, 2000
This paper introduces the analysis of the efficiency and transferred power of an inductive link circuit with different network configurations of capacitors connected to primary and secondary coils. The best performance for both cited objective functions was observed with two capacitors connected to the input coil and two capacitors connected to the output coil. However, the output equations in this circuit configuration for both efficiency and output power are very complex and a numerical method had to be applied to compute the capacitors values. Since an exhaustive search would be long, some simplifications were assumed to reduce the search space and the processing time. Thus, a search algorithm based on a randomized method was developed and successfully applied. The results for both efficiency and output power of four capacitors configuration were compared with other usual approaches, such as the single and two capacitors compensation. Finally, a basic prototype was built and the theoretical results were validated. Both simulated and experimental results of the four capacitor configuration showed a significant improvement on the efficiency and output power of the inductive link.
Loss Induced Maximum Power Transfer in Distribution Networks
2018 Power Systems Computation Conference (PSCC), 2018
In this paper, the power flow solution of the two bus network is used to analytically characterise maximum power transfer limits of distribution networks, when subject to both thermal and voltage constraints. Traditional analytic methods are shown to reach contradictory conclusions on the suitability of reactive power for increasing power transfer. Therefore, a more rigorous analysis is undertaken, yielding two solutions, both fully characterised by losses. The first is the well-known thermal limit. The second we define as the 'marginal lossinduced maximum power transfer limit'. This is a point at which the marginal increases in losses are greater than increases in generated power. The solution is parametrised in terms of the ratio of resistive to reactive impedance, and yields the reactive power required. The accuracy and existence of these solutions are investigated using the IEEE 34 bus distribution test feeder, and show good agreement with the two bus approximation. The work has implications for the analysis of reactive power interventions in distribution networks, and for the optimal sizing of distributed generation.
Maximum Electrical Power Extraction from Sources by Load Matching
Energies
This paper describes the matching of various loads to sources (including nonlinear ones). The purpose of matching is to extract the maximum available power from the source. This has particular importance for renewable sources and energy-harvesting devices, in which unused energy is just wasted. The main innovations in this paper include (and followed by examples) simplified calculation of the matching parameter for a controllable load and matching by means of a family of power-conservative two-port networks, denoted POPI (Pin = Pout), such as transformers, gyrators, loss-free resistors (LFRs) and series LFRs (SLFRs). An additional innovation described in this paper is a new, simplified model of an HF power amplifier based on the series LFR concept. This model predicts that the efficiency of the HF power amplifier operated under the matched-mode condition can significantly exceed the 50% efficiency limit that is predicted by the conventional model. As HF power amplifiers drive antenn...
Design guideline of capacitive power transfer system to achieve targeted output power
International Journal of Power Electronics and Drive Systems, 2023
Power transfer capability of the capacitive power transfer (CPT) system is dependent on the dimensions of capacitive coupler, which should be correctly designed to meet the required amount of output power. This paper presents a guideline to design the conductive plates used in CPT system to achieve a targeted output power. For a given operating frequency, resonant inductance, DC input voltage, load resistance, and the air gap between plates, the required cross-sectional area of conductive plates is obtained using this guideline. It has been guided through the design procedure which is explained in detail. A step-by-step guide to design a 5-watts CPT system is demonstrated as a design example. The proposed design guideline is verified by the experiment which shows the closeness between measured and targeted output power. Design error is obtained as low as 3.6 percent.
About the maximum transfer of power in time-varying linear circuits
Advanced Materials Research, 2013
This paper discusses the mathematical conditions of achievement of maximum power transfer from source to load in electric circuits where their basic elements (resistance, inductance and capacitance) are eventually linear and time-varying but not necessarily everywhere timedifferentiable. This last concern is seen to be relevant for the inductive part of the circuit whose time-derivative, where it exists, plays the role of a resistor while it has an impulsive characterization at time instants where such a time-derivative does not exist. The power transfer degradation through time is also characterized related to the initial values of the circuitry provided that the source remains unaltered through time.
Single variable expressions for the efficiency of a reciprocal power transfer system
International Journal of Circuit Theory and Applications, 2016
The analytical expressions for the efficiency of a reciprocal power transfer system as function of multiple parameters, i.e. the elements of its impedance matrix, already exist. In this work, closed expressions for this efficiency as function of a single parameter, i.e. the extended kQ factor, are derived. This is done for three representative configurations: (i) maximum efficiency, (ii) maximum power transfer and (iii) conjugate image setup. The derived formulas are useful for the design and optimization of different types of power transfer systems.
IEEJ Journal of Industry Applications, 2018
Recently, the dual transmitting resonator wireless power transfer system (DTR-WPT) has been proposed as a promising technique for the power supply of mobile apparatus. Although this technique has been reported to be effective for increasing the output power as well as for covering a wide area during wireless power transfer, the complicated magnetic coupling among two transmitting resonators and one receiving resonator makes it difficult to develop practical design optimization methods, thus hindering practical applications of this technique. The purpose of this paper is to propose a design optimization method for the load impedance of DTR-WPT. This method is derived based on a novel simple equivalent circuit model of the DTR-WPT. The optimum impedance derived using this method as well as the appropriateness of the equivalent circuit were verified experimentally, thus validating usefulness of the proposed method for the practical application of DTR-WPT.
Optimization of wireless power transfer using artificial neural network: A review
Microwave and Optical Technology Letters, 2019
Wireless power transfer (WPT) is widely explored and applied nowadays because of its simplicity in transferring power without using wire, easy maintenance, and equipment mobility. Due to mobility and compatibility attributes, WPT is utilized in powering biomedical devices, small electronic equipment, wireless sensor, mobile phones, and high voltage applications (eg, electric vehicles). The implementation of artificial neural network (ANN) in WPT has emerged as a powerful/prominent tool for estimating the performance parameters due to its learning and significant features. Such implementation can minimize design complexity and time-consuming calculations. An early application of ANN employs the information derived from the collectively measured processes for training the ANN algorithm. After a suitable training process, the network output can be considered in place of computationally thorough representations to speed up the result search. To obtain precise result and optimize the parameters in WPT, several popular ANN algorithms have been used by researchers. This review paper highlighted the latest research specifically regarding the implementation of ANN in WPT, which included the types of ANN implemented in WPT, current WPT problem investigation that used ANN, and a comparison between the techniques. Moreover, the challenges and constraints of ANN techniques were elucidated at the end of this paper.
Investigation of correlation of design parameters in wireless power transfer system
IET Science, Measurement & Technology
Achieving higher power transfer efficiency with permissible output load power is a formidable challenge in designing a magnetically coupled resonant wireless power transfer system. Consequently, to instigate the power transfer characteristics, the theoretical models based on reflected load theory as well as lumped circuit models have been employed, which have been substantiated with the experimental measurements. It has been apprehended that maximum efficiency as well as the power delivered to the load can be enriched from the depreciated value through appropriate deliberation of coil's quality factor (coil design dependent) and coupling coefficient with acceptable operating frequency under different electric load conditions. The obtained results illuminate the correlation between the maximum power transfer ability and the quality factor of the coils, as well as the coupling coefficient, under different electric load conditions. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Progress In Electromagnetics Research B, 2019
This paper studies the power transfer characteristics of a resonator array for inductive power transfer by means of the accurate analytical solution of its circuit model. Through the mathematical inversion of a tridiagonal matrix, it is possible to obtain closed-form expressions for the current in each resonator and consequently expressions for the power transfer and efficiency of the system. The method can be applied to a resonator array powering a load at the end of the array or a receiver facing the array at any position. With the expressions obtained, it is possible not only to achieve a better understanding of the power transfer characteristics in resonator arrays but also to obtain the conditions for maximum power transfer or maximum efficiency, for several conditions and parameters of the system. A prototype of a stranded-wire resonator array powered by a resonant inverter, capable of delivering power to a load from 65 W to 90 W with efficiency values between 63% and 88%, was built in order not only to validate the expressions obtained but also to show their practical applicability and demonstrate that these arrays can be used for higher power transfer applications.
Performance analysis of inductive power transfer using JMAG-designer
Bulletin of Electrical Engineering and Informatics, 2023
Due to its advantage of sending electrical power from the transmitter source to the receiver load with no physical contact, wireless power transfer (WPT) has rapidly gained popularity in recent years. They can be used in a variety of applications, including induction cooking, mobile phone charging, radio frequency identification (RFID), and electric vehicles (EVs). Using JMAGdesigner, a simulation of series-parallel inductive power transmission has been investigated in this research. This study aims to determine how the output power and efficiency change depending on how many coils turn in the transmitter and receiver. The number of coils turn in the transmitter is fixed which is 20 turns, the number of coils turn in the receiver is variable and ranges between 15 and 30, and the air gap or distance between the coupling coils is set at 10 cm. The selected frequency to be used in this simulation is between 10 and 50 kHz. According to the absorption result, the output power and efficiency rise when the receiver has more coil turns than the transmitter, and the output power and current rise along with an increase in resonance frequency.
CONCEPTS, QUALITY FACTOR AND EFFICIENCY OF " WIRELESS POWER TRANSFER "
The present text provides information regarding introductory concept of wireless power transfer through some of the existing technologies and evaluate its quality factor as well as deals with certain methods of improving the efficiency of wireless power transfer. Its figure of merit, transfer loss, quality factor and efficiency been calculated and analysed.
Analysis and Optimization of Wireless Power Transfer Link
In this paper, a high efficiency Gallium nitride (GaN), HEMT (High Electron Mobility Transistor) class-E power amplifier for the wireless power transfer link is designed and simulated on PSpice. A four-coil wireless power transfer link is modeled for maximum power transfer efficiency on ADS (Advanced Design System) and frequency splitting phenomenon is demonstrated, explained and analyzed. Two resonant coupling structures, series & mixed, are presented and compared. The efficiency performance of the link is studied using spiral and helical antennas of different wire make. In addition, techniques for improving efficiency of the wireless power transfer systems with changing coupling coefficient viz. frequency splitting phenomenon of the coils are proposed.