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Multivariable optimal control of wireless power transfer systems with series-parallel compensation
... att.). Attēlā skaidri redzams, ka pie vājas induktīvās saites 30 starp spolēm fāzes frekvences raksturlīkne šķērso nulli tikai vienu reizi -pie primārā un sekundārā rezonanses kontūra rezonanses frekvences (f rez ) 31 . Frekvenci f rez sauc par BEP sistēmas pamat rezonanses frekvenci. ...
Chapter 1 of this book presents standards, classification and history of wireless power transfer as well as a description of the parameters of wireless power transfer systems. Chapter 2 is devoted to an overview of wireless power transfer techniques. Major attention is focused on the resonant-inductive wireless power transfer. In Chapter 3, resonant-inductive wireless battery charging systems are discussed. The book can be useful for electronics, electrical and power engineering students. It may also be interesting to school students who study enhanced physics courses and to other people interested in power transfer and conversion.
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Approaches to get higher efficiency of switching-frequency-modulated inductive-resonant wireless power transfer systems (WPT) are proposed in the paper. The approaches are verified by using simulations. The approaches are based on utilization of modified resonant tanks with electronically-switched capacitors or electronically tunable capacitors. The approaches can sufficiently improve efficiency, reduce RMS and peak values of currents and reduce output current ripples of frequency-modulated WPT systems for battery charging.
... Inductive-resonant wireless power transfer (WPT) to electrical loads has become popular area of research in the field of power electronics. One of the main applications of the technology is wireless charging of batteries of electrical vehicles, biomedical implanted devices, mobile electronic devices, etc. [1] - [5]. The inductive-resonant WPT technology is applicable for both low and high power levels, but it is suitable only for small distances up to several tens of cm (but often it is enough to charge wirelessly batteries of electrical vehicles or mobile electronic equipment). ...
This paper deals with inductive-resonant wireless power transfer (WPT) systems based on multilevel T-type inverters with simultaneous modulation of switching frequency and duty cycle. The effect of the hybrid modulation on the performance characteristics of closed-loop WPT systems with T-type multilevel inverters for wireless battery charging is studied in details by using simulation. Performance characteristics of the WPT system with the hybrid modulation are compared with that of WPT system without modulations and with classical switching frequency modulation. It is shown that T-type multilevel-inverter based WPT systems with hybrid modulation exhibit better performance than T-type multilevel-inverter based WPT systems with classical switching frequency modulation in terms of lower RMS and peak values of currents as well as better efficiency.
Being switch-mode in nature, wireless power transfer systems (WPT) emit significant conducted electromagnetic emissions (EME). In this paper for the first time multi switching frequency scheme is applied to closed-loop WPT systems for reduction of conducted EME. In this method inductive resonant WPT system operates at different discrete switching frequencies sequentially. The effect of the multi switching frequency scheme on main performance characteristics of inductive-resonant wireless battery charger operating in constant current mode is analyzed by using simulations. Performance characteristics of the WPT system with the multi switching frequency scheme are compared with that of WPT system without modulations and with classical switching frequency modulation. It is shown that wireless battery charger with the multi switching frequency scheme exhibits performance similar to performance of wireless battery charger with classical switching frequency modulation but complexity of control is lower.
Abstract— this paper describes components estimation process for inductive power transfer approach based on Z-source network. Proposed model covers main parameters of the system and gives efficient way to evaluate optimal parameters for fixed switching frequency and distance.
This paper proposes a new topology-reconfigurable capacitive compensation network, aiming to achieve the energy encryption of the contactless charging for multiple electric vehicles (EVs). The proposed variable topology of compensation network consists of a M
$\times$
N capacitor matrix, where capacitors can be connected either in series or in parallel by controlling switches. Then, the proposed capacitor matrix can be formed in the series-parallel (SP) and the series-parallel-series-parallel (SP2) topologies according to the adjustment of the resonant frequency. In such ways, the proposed topology-reconfigurable capacitor matrix can significantly extend the capacitive compensating range while reducing the number of capacitors, thus effectively enhancing the security performance of multiple-objective contactless charging systems. Lastly, this paper gives the simulated and experimental results to verify the theoretical analysis, which can further illustrate the feasibility of the proposed topology-reconfigurable capacitor matrix for the energy encryption of EV contactless charging systems.
This paper describes novel inductive power
transfer approach based on Z-source network with auxiliary
circuit. Theoretical analysis along with simulation verification
is presented. The main advantages and limitations of the
proposed solutions are discussed in conclusions.
In a wireless power transfer (WPT) system via coupled magnetic resonances (CMR), the power transfer efficiency (PTE) drastically decreases with the transfer distance or the load changing. In this paper, the causes of efficiency degradation were analyzed, and an automatic impedance matching method based on the feedforward-backpropagation (BP) neural network was proposed to maintain the PTE at a reasonable level. To validate and test the performance of the proposed method, a WPT automatic impedance matching simulation system was implemented. Moreover, a prototype based on the proposed method was built and dynamic matching experiments were performed. The simulation results show that the algorithm efficiency of the proposed BP method was 108.5% higher than that of the genetic algorithm. The experimental results show that the PTE was improved up to 78.33% and this was closely maintained within a distance of 10 to 30 cm, which is consistent with the simulation result.
In this paper, the Z-source converter is introduced to power factor correction (PFC) applications. The concept is demonstrated through a wireless power transfer (WPT) system for electric vehicle battery charging, namely Z-source resonant converter (ZSRC). Due to the Z-source network (ZSN), the ZSRC inherently performs PFC and regulate the system output voltage simultaneously, without adding extra semiconductor devices and control circuitry to the conventional WPT system such as conventional PFC converters do. In other words, the ZSN can be categorized as a family of the single-stage PFC converters. In addition, the ZSN is suitable for high-power applications since it is immune to shoot-through states, which increases reliability and adds a boost feature to the system. The ZSRC-based WPT system operating principle is described and analyzed in this paper. Simulations and experimental results based on a 1-kW prototype with 20-cm air gap between the system primary and secondary sides are presented to validate the analysis and demonstrate the effectiveness of the ZSN in the PFC of the WPT system.
Capacitive power transfer (CPT) has been investigated as an alternative wireless power transfer technology based on electric field coupling. The coupling interface of CPT is formed by a pair of "capacitors" in series with the power source and load. The effective capacitance ranges from tens to a few hundreds of picofarads, yielding high impedance. Therefore, in most CPT systems, a tuning inductor is connected in series with the coupling interface for circuit compensation and power transfer capability enhancement. However, this compensation method suffers from high voltage spikes from the inductor if the secondary side load is removed suddenly causing electrical and health hazards. To address the issue, this paper proposes a CPT system based on a Z-impedance compensation network with inherent open-circuit and short-circuit immunity. It also has the voltage boost capability as a Z-source inverter. Its operating principle is described and a set of design equations are given. Both simulations and experimental results from a 5 W low power design have demonstrated that the proposed compensation method using the Z-impedance matching network exhibited open-circuit and short-circuit immunity, could boost up the output voltage by 50% with power efficiency exceeding 80%.
This paper discusses the feasibility of a real-time active matching circuit (MC) for wireless power transfer applications, especially for biomedical systems. One prototype of low-cost real-time automatic MC, utilizing a variable circuit topology, including discrete passives and p-i-n diodes, has been implemented and the principle has been verified by measurements. One genetic algorithm was introduced to optimize the design over a wide range of impedances to match. As a result of preliminary operation verification tests, the proposed real-time MC system results in improving the transfer coefficient in the range of 10–16-cm coil separation distance a maximum of 3.2 dB automatically in about 64 ms. Similar performance improvement results were observed in additional tests under misaligned conditions, as well as for nonsymmetrical Tx–Rx coil configurations further verifying the potential applicability of the proposed system to practical biomedical devices.
Inductive power transfer (IPT) and capacitive power transfer (CPT) are the two most pervasive methods of wireless power transfer (WPT). IPT is the most common and is applicable to many power levels and gap distances. Conversely, CPT is only applicable for power transfer applications with inherently small gap distances due to constraints on the developed voltage. Despite limitations on gap distance, CPT has been shown to be viable in kilowatt power level applications. This paper provides a critical comparison of IPT and CPT for small gap applications, wherein the theoretical and empirical limitations of each approach are established. A survey of empirical WPT data across diverse applications in the last decade using IPT and CPT technology graphically compares the two approaches in power level, gap distance, operational frequency, and efficiency, among other aspects. The coupler volumetric power density constrained to small gap sizes is analytically established through theoretical physical limitations of IPT and CPT. Finally, guidelines for selecting IPT or CPT in small gap systems are presented.
In a wireless power transfer (WPT) system via the magnetic resonant coupling, one of the most challenging design issues is to maintain a reasonable level of power transfer efficiency (PTE), even when the distance between the transmitter and the receiver changes. When the distance varies, the PTE drastically decreases due to the impedance mismatch between the resonator of the transmitter and that of the receiver. This paper presents a novel serial/parallel capacitor matrix in the transmitter, where the impedance can be automatically reconfigured to track the optimum impedance-matching point in the case of varying distances. The dynamic WPT matching system is enabled by changing the combination of serial and parallel capacitors in the capacitor matrix. An interesting observation in the proposed capacitor matrix is that the resonant frequency is not shifted, even with capacitor-matrix tuning. In order to quickly find the best capacitor combination that achieves maximum power transfer, a window-prediction-based search algorithm is also presented in this paper. The proposed resonance WPT system is implemented using a resonant frequency of 13.56 MHz, and the experimental results with 1W power transfer show that the transfer efficiency increases up to 88$%$ when the distance changes from 0 to 1.2 m.
In this study, a comprehensive review of existing technological solutions for wireless power transfer used in electric vehicle battery chargers is given. The concept of each solution is thoroughly reviewed and the feasibility is evaluated considering the present limitations in power electronics technology, cost and consumer acceptance. In addition, the challenges and advantages of each technology are discussed. Finally, a thorough comparison is made and a proposed mixed conductive/wireless charging system solution is suggested to solve the inherent existing problems.
Recently, a highly efficient midrange wireless transfer technology using electromagnetic resonance coupling has been proposed and has received much attention due to its practical range and efficiency. The resonance frequency of the resonators changes as the gap between the resonators changes. However, when this technology is applied in the megahertz range, the usable frequency is bounded by the industrial, scientific, and medical (ISM) band. Therefore, to achieve maximum power transmission efficiency, the resonance frequency has to be fixed within the ISM band. In this paper, an automated impedance matching (IM) system is proposed to increase the efficiency by matching the resonance frequency of the resonator pair to that of the power source. The simulations and experiments verify that the IM circuits can change the resonance frequency to 13.56 MHz (in the ISM band) for different air gaps, improving the power transfer efficiency. Experiments also verified that automated IM can be easily achieved just by observing and minimizing the reflected wave at the transmitting side of the system.
Single Switch Multi-Winding Wireless Power Transfer System Based On Z-Source Network
- K Kroics
- O Husev
- B Pakhaliuk
- J Zakis
- R Strzelecki
- O Veligorskyi
Single Switch Multi-Winding Wireless Power Transfer System Based on Z-Source Network
- kroics