726 research outputs found
Design Of Capacitive Power Transfer Using A Class-E Resonant Inverter
This paper presents a capacitive power transfer (CPT) system using a Class-E resonant inverter. A Class-E resonant inverter is chosen because of its ability to perform DC-to-AC inversion efficiently while significantly reducing switching losses. The proposed CPT system consists of an efficient Class-E resonant inverter and capacitive coupling formed by two flat rectangular transmitter and receiver plates. To understand CPT behavior, we study the effects of various coupling distances on output power
performance. The proposed design is verified through lab experiments with a nominal operating frequency of 1 MHz and 0.25 mm coupling gap. An efficiency of 96.3% is achieved. A simple frequency tracking unit is also proposed to tune the operating frequency in response to changes in the coupling gap. With this resonant frequency tracking unit, the efficiency of the proposed CPT system can be maintained within 96.3%–91% for the coupling gap range of 0.25–2 mm
Analysis and design of a 1 kW Class-GD ultrasonic generator
Word processed copy.Includes bibliographical references (leaves 66-70)
Simulation Study on Self-frequency Tracking Control Strategy for Inductive Power Transfer System
This paper presents a closed loop Inductive Power Transfer (IPT) system. In this work, the Phased Lock Loop control system is used to control the frequency of Class E resonant converter circuit. Furthermore, self-frequency tracking control strategy with simple detection circuit is proposed as a feedback circuit to IPT system. Through this method, the frequency drifting that is due to variation in reactive components or mutual inductive coupling can be avoided successfully. The IPT system with and without frequency tracking is analyzed at different coupling coefficient. Simulation results confirm that the Class E resonant power converter circuit with frequency tracking gives a better output result with 92% efficiency at 0.8 of coupling coefficien
Fuzzy-logic-based control, filtering, and fault detection for networked systems: A Survey
This paper is concerned with the overview of the recent progress in fuzzy-logic-based filtering, control, and fault detection problems. First, the network technologies are introduced, the networked control systems are categorized from the aspects of fieldbuses and industrial Ethernets, the necessity of utilizing the fuzzy logic is justified, and the network-induced phenomena are discussed. Then, the fuzzy logic control strategies are reviewed in great detail. Special attention is given to the thorough examination on the latest results for fuzzy PID control, fuzzy adaptive control, and fuzzy tracking control problems. Furthermore, recent advances
on the fuzzy-logic-based filtering and fault detection problems are reviewed. Finally, conclusions are given and some possible future research directions are pointed out, for example, topics on two-dimensional networked systems, wireless networked control systems, Quality-of-Service (QoS) of networked systems, and fuzzy access control in open networked systems.This work was supported in part by the National Natural Science Foundation of China under Grants 61329301,
61374039, 61473163, and 61374127, the Hujiang Foundation of China under Grants C14002 andD15009, the Engineering and Physical Sciences Research Council (EPSRC) of the UK, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany
Mitigation of DC Current Injection in Transformerless Grid-Connected Inverters
PhD ThesisWith a large number of small-scale PV plants being connected to the utility grid, there is increasing
interest in the use of transformerless systems for grid-connected inverter photovoltaic applications.
Compared to transformer-coupled solutions, transformerless systems offer a typical efficiency
increase of 1-2%, reduced system size and weight, and reductions in cost. However, the removal
of the transformer has technical implications. In addition to the loss of galvanic isolation, DC
current injection into the grid is a potential risk. Whilst desirable, the complete mitigation of DC
current injection via conventional current control methods is known to be particularly challenging, and
there are remaining implementation issues in previous studies. For this reason, this thesis aims to
minimize DC current injection in grid-connected transformerless PV inverter systems.
The first part of the thesis reviews the technical challenges and implementation issues in published
DC measurement techniques and suppression methods. Given mathematical models, the
performance of conventional current controllers in terms of DC and harmonics mitigation is
analyzed and further confirmed in simulations and experiments under different operating
conditions. As a result, the second part of the thesis introduces two DC suppression methods, a DC
voltage mitigation approach and a DC link current sensing technique. The former method uses a
combination of a passive attenuation circuit and a software filter stage to extract the DC voltage
component, which allows for further digital control and DC component mitigation at the inverter
output. It is proven to be a simple and highly effective solution, applicable for any grid-connected
PV inverter systems. The DC link sensing study then investigates a control-based solution in which
the dc injection is firstly accurately determined via extraction of the line frequency component
from the DC link current and then mitigated with a closed loop. With an output current
reconstruction process, this technique provides robust current control and effective DC suppression
based on DC link current measurement, eliminating the need for the conventional output current
sensor. Results from rated simulation models and a laboratory grid-connected inverter system are
presented to demonstrate the accurate and robust performance of the proposed techniques.
This thesis makes a positive contribution in the area of power quality control in grid-connected
inverters, specifically mitigating the impact of DC injection into the grid which has influences on
the network operating conditions and the design and manufacture of the PV power converter itsel
Design Optimization of Inductive Power Transfer Systems for Contactless Electric Vehicle Charging Applications
Contactless Electric Vehicle (EV) charging based on magnetic resonant induction is an emerging technology that can revolutionize the future of the EV industry and transportation systems by enabling an automated and convenient charging process. However, in order to make this technology an acceptable alternative for conventional plug-in charging systems it needs to be optimized for different design measures. Specifically, the efficiency of an inductive EV charging system is of a great importance and should be comparable to the efficiency of conventional plug-in EV chargers.
The aim of this study is to develop solutions that contribute to the design enhancement of inductive EV charging systems. Specifically, generalized physics-based design optimization methods that address the trade-off problem between several key objectives including efficiency, power density, misalignment tolerance, and cost efficiency considering critical constraints are developed. Using the developed design methodology, a 3.7kW inductive charging system with square magnetic structures is investigated as a case study and a prototype is built to validate the optimization results. The developed prototype achieves 93.65% efficiency (DC-to-DC) and a power density of 1.65kW/dm3.
Also, self-tuning power transfer control methods with resonance frequency tracking capability and bidirectional power transfer control are presented. The proposed control methods enhance the efficiency of power converters and reduce the Electromagnetic Interference (EMI) by enabling soft-switching operations. Several simplified digital controllers are developed and experimentally implemented. The controllers are implemented without the use of DSP/FPGA solutions. Experimental tests show that of the developed simplified controllers can effectively regulate the power transfer around the desired value. Moreover, the experiments show that compared to conventional converters, the developed converters can achieve 4% higher efficiency at low power levels.
Moreover, enhanced matrix converter topologies that can achieve bidirectional power transfer and high efficiency with a reduced number of switching elements are introduced. The self-tuning controllers are utilized to design and develop control schemes for bidirectional power transfer regulation. The simulation analyses and experimental results show that the developed matrix converters can effectively establish bidirectional power transfer at the desired power levels with soft-switching operations and resonance frequency tracking capability. Specifically, a direct three-phase AC-AC matrix converter with a reduced number of switches (only seven) is developed and built. It is shown that the developed converters can achieve efficiencies as high as 98.54% at high power levels and outperform conventional two-stage converters
RF Power Transfer, Energy Harvesting, and Power Management Strategies
Energy harvesting is the way to capture green energy. This can be thought of as a recycling process where energy is converted from one form (here, non-electrical) to another (here, electrical). This is done on the large energy scale as well as low energy scale. The former can enable sustainable operation of facilities, while the latter can have a significant impact on the problems of energy constrained portable applications. Different energy sources can be complementary to one another and combining multiple-source is of great importance. In particular, RF energy harvesting is a natural choice for the portable applications. There are many advantages, such as cordless operation and light-weight. Moreover, the needed infra-structure can possibly be incorporated with wearable and portable devices. RF energy harvesting is an enabling key player for Internet of Things technology. The RF energy harvesting systems consist of external antennas, LC matching networks, RF rectifiers for ac to dc conversion, and sometimes power management. Moreover, combining different energy harvesting sources is essential for robustness and sustainability.
Wireless power transfer has recently been applied for battery charging of portable devices. This charging process impacts the daily experience of every human who uses electronic applications. Instead of having many types of cumbersome cords and many different standards while the users are responsible to connect periodically to ac outlets, the new approach is to have the transmitters ready in the near region and can transfer power wirelessly to the devices whenever needed. Wireless power transfer consists of a dc to ac conversion transmitter, coupled inductors between transmitter and receiver, and an ac to dc conversion receiver. Alternative far field operation is still tested for health issues. So, the focus in this study is on near field.
The goals of this study are to investigate the possibilities of RF energy harvesting from various sources in the far field, dc energy combining, wireless power transfer in the near field, the underlying power management strategies, and the integration on silicon. This integration is the ultimate goal for cheap solutions to enable the technology for broader use. All systems were designed, implemented and tested to demonstrate proof-of concept prototypes
Roadway-Embedded Transmitters and Multi-Pad Receivers for High Power Dynamic Wireless Power Transfer
Electric vehicles (EVs) offer considerable economic and environmental benefits to society. Despite the decreasing vehicle costs and increasing range of newer EVs, the problem of range anxiety still exists. Range anxiety, at its core, is an issue of charging speeds rather than a concern about the driving range. Dynamic wireless charging of EVs is seen as a potential solution to this issue of range anxiety. Further, wireless charging technology also helps the push towards level 5 autonomy and opens new opportunities for how an EV can be utilized.
Dynamic wireless power transfer (DWPT) systems typically require a high initial investment due to the scale of deployment needed and require a certain level of EV adoption before they become economically viable. The challenges facing DWPT technologies are broadly categorized into development, deployment and operation challenges. To address the deployment challenges, this dissertation presents the pavement integration of DWPT systems, and the design and validation of concrete-embedded wireless charging pads. To improve infrastructure utilization and address the operation challenge, different vehicle classes need to recharge from the same charging infrastructure. This is made possible by the use of multi-pad receivers, which allow different vehicle classes to receive different power levels using the same charging infrastructure. This work presents a scaled-down version of a multi-pad receiver system to demonstrate the operation and scalability of these modular receivers.
To help further reduce the cost of development and implementation of DWPT systems, finite element method (FEM) and circuit simulation models are presented. The time-domain simulations can be used to develop and validate various control and communication schemes without the need for expensive hardware implementation. Finally, leakage magnetic field reduction to ensure safety and compliance for DWPT systems is discussed, and an example system is analyzed using FEM simulations
Design and Control of Power Converters 2019
In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc
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