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This article presents a coordinated control method used for wireless power transfer (WPT) systems. This method can improve WPT system transmission efficiency while maintaining the constant output voltage. First, the topology of the DC–DC converter is selected and the equivalent circuit model of the WPT system is established. Then, the WPT system characteristics are discussed and the mutual inductance estimation process is presented. Furthermore, the coordinated control method is proposed, where the constant voltage output is achieved by connecting the Buck–Boost converter after the diode rectifier. Meanwhile, the optimal phase shift angle is calculated and sent to the controller to achieve maximum transmission efficiency tracking control, according to the measured load voltage and current. Finally, simulations and experiments are adopted to verify the proposed coordinated control method. The experimental results indicate that the average system transmission efficiency is increased by 1.80% and the efficiency fluctuation is decreased by 2.67% when the system load resistance varies, while the average system transmission efficiency is increased by 1.80%, and the efficiency fluctuation is decreased by 3.14% when the mutual inductance changes. This means the proposed coordinated control method is effective under the conditions of the WPT load and mutual inductance variations. [ABSTRACT FROM AUTHOR]

This article proposes a primary-side linear control strategy to realize the constant current (CC)/voltage (CV) charging for the wireless power transfer system, based on the LCC-N magnetic integration and non-compensation circuit. Different from the conventional compensation topology used in control strategies, this article combines magnetic integration structure on the primary side and noncompensation topology on the secondary side, which reduces the size of the additional compensation inductor and makes the secondary side more compact. Moreover, the primary-side linear control strategy is studied by using the improved load parameters identification method, based on the LCC-N topology. First, the LCC-N magnetic integration and noncompensation topology is introduced. An improved load parameters identification method considering the non-pure resistive input impedance characteristics of the rectifier is proposed to identify the current, voltage and equivalent resistance of the load, based on the LCC-N topology. In the process of identification, the complicated relationship between the input impedance of the rectifier and the load is needless. Then, according to the LCC-N output characteristics and identified load parameters, the relationship between the input voltage and load current and voltage is simplified to linear through the linear superposition of fundamental wave and third harmonic. And a linear control strategy on the primary side is proposed to achieve CC/CV output. Finally, a 1 kW WPT prototype is built to verify the effectiveness of the proposed control strategy. The experimental results show that the maximum error of the output current is 1.8% during the CC charging, and the maximum error of the output voltage is 1.2% during the CV charging. [ABSTRACT FROM AUTHOR]

This article presents a secondary side voltage and current estimation method in the wireless power transfer (WPT) systems on the basis of load parameter identification. In the application of limited space and weight, it is difficult to arrange sensors to monitor the high-frequency voltages and currents in the WPT secondary side. Compared with the conventional methods, joint estimation of several secondary side voltages and currents is achieved in this article to monitor WPT electrical stress, based on only the RMS value of one primary side measured voltage. First, an equivalent circuit model of the WPT system with the dual-side LCC compensation networks and rectifier load is established. Then, T-type equivalent circuit of the coils and compensation capacitors is adopted to simplify the model. Moreover, the relationship between the RMS value of the primary side measured voltage and system equivalent load resistance is obtained and simplified for the load parameter identification. Furthermore, the secondary side voltage and current estimation method are proposed based on the identified system equivalent load resistance. Finally, a WPT prototype is developed and the experimental results indicate that the proposed method can achieve high estimation accuracy under the conditions of battery load voltage change, inverter phase-shift angle variation, and coil misalignment. [ABSTRACT FROM AUTHOR]

Dynamic wireless power transfer (DWPT) technology is gradually making the prospect of charging on road of EVs (electirc vehicles) possible. However, DWPT system should be optimized in many aspects before it can really be utilized on road. For example, the control of energy transfer for a DWPT system is much complicated than a static wireless power transfer (WPT) system since the coupling of transceiving coils changes with the moving of the EV. In this article, an energy transfer control method based on the estimation of the load and mutual inductance of the segmented DWPT system is proposed. The relation between the load and the reflected impedance of the primary side is studied, and the parameters of the secondary-side LCC network are tuned to avoid the two-solution problems in the estimation of the load. Based on the results of estimation, a two-cases controlling strategy is proposed to switch between power-on station and detection station of the DWPT system according the target of energy transferring. A 800-W prototype of four-transmitting-coil dynamic WPT system is built and experiments show that the proposed energy-transfer control is proved to be efficient to regulate the energy and achieve fast response characteristics. Compared with the traditional controlling methods which usually aim to achieve maximum energy transfer, the method in this article can control the transferred energy according to the target value of energy, making the control more flexible without the use of communication. [ABSTRACT FROM AUTHOR]

This article proposes an receiver position identification (RPI) method based on magnetic integration compensation inductance, using the voltage and current of the magnetic integration compensation inductance, and the transmitter current. Compared with the conventional methods, the proposed method does not add additional detection coils and position sensors, and RPI is realized based on electric parameters of the primary magnetic integration compensation inductance and transmitter. First, the coupling relationships between the magnetic integration compensation inductance, transmitter and receiver with different wiring modes are analyzed. Meanwhile, an integration compensation inductance structure with minimal coupling impact on the receiver and transmitter coils is determined. Then, based on the magnetic integration compensation inductance structure, the RPI method is analyzed, which can detect the receiver position in the x–y plane without secondary-side information. Finally, the proposed RPI method is experimentally verified, and the results show that the proposed method can effectively identify the receiver position. [ABSTRACT FROM AUTHOR]

This paper presents the analysis and design of the wireless power transfer (WPT) system based on the inductor‐capacitor‐capacitor/none (LCC/N) magnetic integration compensation circuit. Compared with the traditional compensation circuits, the proposed LCC/N compensation circuit features the magnetic integration and the secondary side without compensation network, which makes the WPT system more compact. First, the fundamental‐harmonic model considering the coupling relationship among magnetically integrated compensation inductor, transmitter coil, and receiver coil is established. Then, the reactive power and turn‐off current of the inverter, transmission power, and efficiency of the WPT system employing LCC/N compensation circuit are analyzed with varied coupling coefficient and load. Furthermore, based on the characteristics analysis of the LCC/N topology, the parameter design criterion of the LCC/N compensation circuit is given. Finally, the analysis and design of the WPT system based on the LCC/N magnetic integration compensation circuit are verified by simulations and experiments. The results show that the characteristics analysis of the WPT system employing the LCC/N compensation circuit is accurate, the inverter can realize zero‐voltage‐switch (ZVS) and the WPT system can achieve the rated power of 1 kW under different offset distances of coils and reach the maximum efficiency of 95.3%. [ABSTRACT FROM AUTHOR]

This article presents battery parameter identification methods considering a rectifier and battery load in wireless power transfer (WPT) systems. In order to reduce the cost and complexity brought by the wireless communication, the load parameters are usually identified through WPT primary side measurement to control the system. Compared with the conventional methods, battery state estimation and load parameter identification are achieved in this article based on only one measured WPT primary side variable. First, the WPT equivalent load is quantitatively expressed, which contains both resistance and inductance components. Then, identification methods for the battery voltage and equivalent resistance are proposed. Meanwhile, selection criteria for the primary side variables are studied to achieve a simple process and high accuracy. Furthermore, a WPT prototype is developed, and the experimental results prove the effectiveness of the equivalent load analysis and the proposed identification methods under the conditions of both battery voltage change and phase shift angle variation. Additionally, the robustness of the proposed methods is studied, considering compensation parameter changes and coil misalignment. Finally, the proposed methods are applied to battery state-of-charge estimation, and the results suggest that the battery power shortage and full charge states can be estimated with high accuracy. [ABSTRACT FROM AUTHOR]

This paper presents the analysis of a rectifier load used for an electric vehicle (EV) wireless charging system, as well as its applications on compensation network design and system load estimation. First, a rectifier load model is established to get its equivalent input impedance, which contains both resistance and inductance components, and can be independently calculated through the parameters of the rectifier circuit. Then, a compensation network design method is proposed, based on the rectifier load analysis. Furthermore, a secondary side load estimation method and a primary side load estimation method are put forward, which adopt only measured voltages and consider the influence of the rectifier load. Finally, an EV wireless charging prototype is developed, and experimental results prove that the rectifier equivalent load can be correctly calculated on conditions of different system load resistances, rectifier input inductances, dc voltages, and mutual-inductances. The experiments also show that rectifier load equivalent inductance will impact system performances, and the proposed methods have good accuracy and robustness in the cases of system parameter variations. [ABSTRACT FROM PUBLISHER]

This paper presents an equivalent model to analyze switch-on process of dynamic wireless charging system of electric vehicle (EV). In the model, system initial state before switching is considered and the full response is used to describe the switch-on process. First, the system states before and after switching are discussed, and an approximate method is proposed to calculate the initial value of converter dc-side voltage in switch-on unit. Then, equivalent transient sources and system transfer functions are obtained to establish the switch-on model. So, the switch-on process can be described through full responses of the selected currents under the excitation of equivalent sources. Furthermore, the proposed model is verified by a developed dynamic wireless EV charging prototype. Also, switch-on transient characteristics are investigated through discussions on system parameter and vehicle speed effects. Finally, a simple way to select the suitable switching position is provided based on the analysis of switching position influence, and its effectiveness has been validated by experimental results. [ABSTRACT FROM PUBLISHER]

Based on the wireless power transfer (WPT) technology, dynamic wireless charging of electric vehicle (EV) is gaining increasing attentions because it promotes the popularization of EV and also serves a new form of clean transportation. In this paper, we introduce the LCC compensation network to WPT system oriented for dynamic wireless EV charging application. First, characteristics of symmetrical T-type network, which is the origin of the favorable LCC compensation network, are summarized. Then, parametric design for both the LCC network used in the secondary side and the LCC network used in the primary side is elaborated theoretically. Furthermore, neighboring effects resulting from the combination of the LCC compensation network and the inevitable inter-coupling between adjacent segments are investigated. Finally, a two-segment LCC compensated dynamic EV charging system is built up and tested with both intra-segment and inter-segment experiments. Spatially averaged output power and dc–dc efficiency of the prototype are measured to be 2.34 kW and 91.3%, respectively. High consistency of the experimental results validates the correctness of the proposed analyses and parametric design method, as well as the suitability of applying LCC network in dynamic wireless EV charging applications. [ABSTRACT FROM PUBLISHER]

In this paper, we present a simple method to extend the feasible rated charging zone of a four-coil coupled wireless charging system (WCS) by optimizing the compensate capacitors of the coils. With the proposed optimizing method, the tolerant lateral misalignment of our WCS prototype has been extended to 44.3 $\%$ of the coil size, achieving a 38.3 $\%$ relative improvement. [ABSTRACT FROM PUBLISHER]