This paper proposes a 3-D omnidirectional wireless power transfer (WPT) system with multiple loads to satisfy the multi-directional charging misalignment condition in space. First, this work builds the equivalent circuit model of an omnidirectional multi-load WPT system, where the amplitude and direction of a magnetic vector can be regulated by adjusting the coil’s current. Second, the relationship between the synthetic magnetic vector and the system’s efficiency is analyzed under different misalignment conditions. Moreover, the current phase difference between transmitters should be set to 0° or 180° depending on the position of the multiple loads. Finally, the magnetic vector regulation method based on the gradient descent algorithm is proposed to realize maximum efficiency point tracking. A 72W prototype is built to validate the feasibility of the proposed method. The efficiency can be improved by 7.1% compared to without such a method.

For an inductive power transfer (IPT) system, stable power transfer is one of the most crucial abilities, but coupling variations can dramatically affect the system's output. This brief proposes a reconfigurable detuned S-LCC compensated IPT system with two discrete frequencies to mitigate power fluctuations due to coupling variations. The original detuned S-LCC topology can operate in one stable region. With the change of the primary capacitor and frequency, the equivalent ac load can be altered, which will create a new stable region. Therefore, the expected coupling range of the detuned S-LCC topology can be extended. First, a detuned S-LCC IPT system with two discrete frequencies is presented, followed by an analysis of the working modes. Then, a detailed parameter design process and switching control are introduced. Finally, a 140-W prototype was constructed to verify the validity of the proposed method. The experimental results demonstrate that the output power fluctuation of the proposed IPT system is less than 5% and the lowest efficiency can be improved from 91.5%% to 94%, with the coupling coefficient varying from 0.27 to 0.63. The proposed method does not need complicated control or dedicated coil design, and it can implement stable power transfer significantly.

Segmented transmitter coils are commonly employed in dynamic wireless power transfer, and automatic switching is a preferred function to limit the transmitter current. This letter proposes a method for segment transmitter automatic switching utilizing a dc-controlled variable inductor (DCCVI), where the dc current can change the ac side's self-inductance. When the coils are decoupled, the dc current is small, so the inductance of the DCCVI is relatively large, leading to the suppression of the transmitter current. When the coils meet certain coupling conditions, the dc current becomes large, leading to a significant reduction in the ac inductance of the DCCVI, resulting in higher transmission power, thereby enabling segment transmitter automatic switching. The proposed method is straightforward and does not need additional position feedback. The experimental results demonstrate that the proposed system can automatically limit the coil current within the range of [0, 0.15] and achieve higher power transmission with higher efficiency within the coupling range of [0.165, 0.3].

Constant current (CC) and constant voltage (CV) outputs are important in the inductive power transfer (IPT) system for battery charging. However, the coupling changes caused by the misalignment between the primary and secondary coils significantly affect the system performance. To address this issue, this article proposes a parameter design method based on the nondominated sorting genetic algorithm-II algorithm for the IPT system to tolerate mutual inductance and load variations in both CC and CV modes. First, a mathematical model of the compensation topology has been established to describe the output characteristics. In addition, the design steps are given to obtain system parameters, and a specific example is designed accordingly. Finally, an experimental setup was built, and the results show that the fluctuation of the output current is less than 0.34% when the load changes from 21 Omega to 24 Omega and the fluctuation of the output voltage is less than 2.69% when the load changes from 24 Omega to 240 Omega as the mutual inductance varies from 20 mu H to 30 mu H. During the whole process of the CC-CV charging, the maximum efficiency is 93.5%.

Inductive power transfer (IPT) technology has garnered considerable attention due to its widespread range of applications. The variation in the air gap can result in variations in the loosely coupled transformer (LCT) parameters, including self-inductance and mutual inductance, due to positional deviations with the ferrite cores on both sides. These variable LCT parameters can damage the resonant tank, ultimately resulting in reduced efficiency. To address this problem, a double-sided LCC-compensated IPT system with a compact decoupled coil is proposed in this article to improve the system's efficiency with respect to the air gap variation. The key idea is to neutralize the variation in LCT parameters through the use of the self-inductance variation of the decoupled coil so that the detuning degree of the system can be suppressed. Subsequently, the analysis and parametric design process of the system are elaborated. Finally, a 1-kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the efficiency of the system proposed in this article varies from 92.63% to 74.81%, as the air gap increases from 30 to 90 mm, wherein the primary and secondary self-inductance and mutual inductance increased by 19.3% and 135.3%, respectively. Compared with the traditional method, the maximum efficiency improvement is up to 8.16%.

In recent years, the application of wireless power transfer (WPT) has drawn vast attention with the advantage of canceling electrical wires. Some electronic devices require various voltage levels for driving and control systems concurrently. Therefore, in this letter, a new multiple regulatable output (MRO) rectifier is proposed for the WPT application to meet the charging demands. The proposed rectifier integrates the Buck converters, and then 4+n semiconductor devices and n inductors are utilized to achieve 1+n output channels, which share a common ground. Besides, the inductor current ripples of the proposed rectifier are lower compared to those of the traditional Buck converters. A 300W prototype with 48V, 18V, and 12V output voltages is built. The experimental results verify the outputs are independently regulatable, and the overall efficiency is higher than 90.08%.

To address the mismatch between the increasing penetration of distributed photovoltaic (DPV) and the stability and profitability of distribution network (DN) operation, this paper proposes a bi-level model that considers the profitability of DN and accommodation capacity of DPV. Combining with cluster control theory, the bi-level model divides the complex DN into different clusters based on the line structure and the load characteristics of DN. In the bi-level model, the optimization object of outer-level model and inner-level model are to minimize the integrated cost of DN, maximize the penetration of photovoltaic and minimize the network loss respectively. For solving the bi-level model, a bi-level hybrid particle swarm optimization (PSO) algorithm is presented. Different cases are set up to validate the feasibility of the established bi-level model and the effectiveness of the presented bi-level PSO algorithm.

Dynamic wireless power transfer is a promising candidate to alleviate the problem of range anxiety and carrying on heavy large-capacity batteries for automatic guided vehicles. In this article, the explanations that the unsymmetrical coupling structures have better performance in the misalignment conditions than the traditional planar couplers are given. Besides, based on the theory of demagnetizing field, an optimized I-shaped structure with a more concentrated magnetic field is presented to consist transmitter array in the dynamic charging system, which has a lower usage of the ferrite and wire and a low output fluctuation during the moving process. A 1.1 kW laboratory prototype is built to verify the feasibility of the proposed system. Experimental results show the system achieves constant output current when the load varies. With single-segment (dual-segment), the output voltage variation is only ±1.03% (±1.18%), and efficiency ranges from 87.22% to 87.98%.

For an inductive power transfer (IPT) system, mobility is one of the most attractive features, but coupling variations can dramatically affect the system's output. In this article, a reconfigurable rectifier-based detuned series-series (SS) compensated IPT system is proposed to tolerate an extensive coupling range and improve the system efficiency simultaneously. The reconfigurable rectifier, which can operate in a full-bridge rectifier mode or a half-bridge rectifier mode, is used to alter the equivalent ac load from one value to the other so the expected coupling range of the detuned SS topology can be extended. At the same time, the system efficiency is also partly improved because the ac load is changed to get closer to the optimal load of the IPT system. First, a detuned SS IPT system with the reconfigurable rectifier is presented and followed by the analysis of the working modes. Then, a detailed parameter design process and switching control of the reconfigurable rectifier are introduced. Finally, a 400-W prototype was constructed to verify the validity of the proposed method. The experimental results demonstrate that the output power fluctuation of the proposed IPT system is less than 17.5% and the lowest efficiency can be improved from 68.6% to 87.5% with the coupling coefficient varying from 0.1 to 0.4. The proposed method can implement significant antimisalignment and efficiency improvement simultaneously, and it is regarded as a potential solution for low-power IPT applications with high spatial mobility.

With the increase of switching frequency, the turn-on current overshoot and turn-off voltage overshoot generated by IGBT switching moment are also increasing rapidly. Under the action of stray inductance, the voltage spike on the circuit load is increasing. Aiming at the problem, an active control circuit based on Miller capacitance is proposed in this paper. The active control circuit takes $du_{ce}/dt$ and $di_{ce}/dt$ as the control signals, which only increases the Miller capacitance of IGBT at the moment of switching, so as to reduce the switching energy loss while effectively suppressing voltage overshoot. Compared with traditional control circuits, the circuit also has the advantages of simple circuit structure, not changing the existing IGBT driving circuit, and easy to integrate with the existing driver. The performance of the designed circuit is verified by simulation software and experimental platform. The results show that the designed circuit can greatly reduce voltage overshoot and current overshoot.

Coupling variation tolerance is one of the most crucial abilities of the inductive power transfer (IPT) system because the variable coupling can dramatically degrade the output power. This letter proposes a clamp circuit-based IPT system with a reconfigurable rectifier featuring high antimisalignment. The clamp circuit can adaptively switch from one stable operating region to the other according to the coupling coefficients. The reconfigurable rectifier can work in half-bridge mode or full-bridge mode, which can build another two adaptively switching stable operating regions such that the proposed IPT system can provide nearly stable output power resisting extensive coupling variations. A 400-W prototype was built to verify the theoretical analysis. The experimental results indicate that the output power fluctuation of the proposed method is only 5.98% when the coupling coefficient varies from 0.1 to 0.4 (400%), and the system efficiency is from 86.1% to 94.3%. The proposed method does not need complicated control or dedicated coil design, and it can implement significant antimisalignment improvement.

Misalignment issue is almost inevitable in an inductive power transfer (IPT) system, leading to unstable power transfer due to the coupling variations. In order to improve the flexibility of the IPT system, the misalignment range of stable power output is desired to be as large as possible. This article proposes a clamped IPT system to improve antimisalignment ability based on the dual-mode operation. The clamped circuit is constructed with a coil and a rectifier connected to the input dc terminal of the inverter. With the effect of the clamped circuit, the operating mode of the system can be adaptively switched to match the required coupling variation region without coupling identification, output detection, or feedback communication. Then, the analysis and parametric design of the system are elaborated. Finally, a 480-W experimental setup was built to verify the feasibility of the proposed method. Experimental results show that the proposed method can maintain stable output power between 440 and 480 W with the coupling varying from 0.14 to 0.39, while the efficiency is from 83.22% to 93.55%.

The inductive power transfer (IPT) technology is drawing increasing attention. Variations in the height of the secondary coil are inevitable due to the fluctuations in the height of the electrical equipment or the pressure of the tires, which leads to variations in the coils' parameters (self-inductances and mutual inductance). The coils' parameters and load variations can dramatically affect the performance of the IPT system. In this article, a unified mathematical model, which can describe multiple compensation topologies, is established. A design method is proposed to obtain suitable topology and component parameters based on the unified mathematical model and the nondominated sorting genetic algorithm II (NSGA-II). In addition, not only the stable output voltage/current is achieved, but the efficiency and cost are also improved. Finally, two experimental prototypes were built to verify the effectiveness, which has the output characteristics of constant current (CC) (3.5 A/600 W) and constant voltage (CV) (72 V/100 W). The results show that the output fluctuations are less than 5.63%, and the maximum efficiency is above 94.69% when the coils' parameters (the primary self-inductance changes from 85.76 to 102.2 mu H, the secondary self-inductance changes from 86.26 to 102.35 mu H, and the mutual inductance changes from 38.2 to 72.1 mu H) and load (double change) vary.

This work proposes an auto-segment control system with multiple transmitters and dual receivers for dynamic inductive power transfer (DIPT) charging. The current of the transmitting coil precisely coupled with the receiver can be enhanced automatically, while the transmitting current will be suppressed when the transmitter is uncoupled with the receiver. Therefore, the electromagnetic interference (EMI) and power loss generated by uncoupled transmitters can be reduced without position detection and switching control. Each receiver includes a power coil and an impedance coil. When the vehicle moves along the road, the impedance coils are utilized to adjust the resonant state of the transmitter, and the power coils operate alternately to maintain a high spatially average power. The relative position and size between transmitters and receivers directly impact the power transfer performance. Therefore, several critical parameters of the magnetic coupler are analyzed and designed to obtain a considerable output power. An around 300 W experimental prototype is established to verify the feasibility of the proposed magnetic coupler and design method. Compared to the auto-segment control system with a single receiver, the spatially average power of the proposed system is improved by twice, and the maximum efficiency is 84.9% in a moving period.

With the wind power capacity increasing, the system frequency fluctuation is aggravated by wind power fluctuation. Therefore, to ensure the stability of system frequency, it is important for the power system to accurately determine the maximum penetration of wind power (MPWP). This paper proposes an analytical method to determine the MPWP considering frequency constraints and wind speed fluctuation (WSF). Firstly, a frequency response model based on wind speed prediction is established, which can reflect the frequency dynamics under WSF and load fluctuation. Then, by using analytical and discretization methods, the maximum steady-state frequency deviation and the maximum rate of change of frequency are solved under WSF and load fluctuation. Based on the solved results, the MPWP can be determined under the frequency constraints. Finally, simulation results confirm the proposed method efficacy in determining the MPWP.

Stable power transmission is one of the key factors in the inductive power transfer (IPT) system. However, misalignment between the primary and secondary sides is almost inevitable in practice, affecting the system performance due to the coupling variation. With the widespread use of IPT technology, it is desired to transfer power from the primary side to the secondary side with a wide misalignment range as large as possible. To address this issue, the design method of the detuned circuit is widely applied in the IPT system. This article analyzes the characteristics of the transfer power of the detuned series–series (S-S) topology with frequency variations and proposes a maintaining stable power transfer method versus wide coupling variation by adopting two discrete frequencies. Further, a design step is given to obtain the system parameters. Theoretical and experimental results are provided to demonstrate the misalignment performance of the proposed method. The results show that the coupling range is extended from (0.115–0.2) to (0.115–0.27) with a 5.6% fluctuation of the output power, and the corresponding efficiency varies from 91.46% to 95.52%.

Misalignment is an unavoidable problem in inductive power transfer (IPT). The coupling variation between coils may lead to the output power change and low efficiency which will reduce the flexibility and stability of the system. In order to ensure the stable power transfer of the system and extend the allowed operation region, this paper proposes an IPT system with a clamp circuit. The proposed IPT system can automatically activate or inactive the clamp circuit in different coupling ranges, so the system can maintain relatively constant power in a large coupling variation. Finally, a 390-W prototype is built to verify the theoretical analysis. The experimental results show that when the coupling coefficient variation is 0.14~0.42, the output power maintains between 355W~390W, and the efficiency is 80.98%~93.31%.

For automatic guided vehicles with dynamic wireless power transfer (DWPT), the vertical variation in the height of the pickup coil is inescapable due to load variations. It can cause changes in the system coil parameters (self-inductances and mutual inductance), further affecting the stability of the system output power. To realize a stable output of the DWPT system when the height of the pickup coil is variable, a parameter design method is proposed in this paper. A mathematical model of output power is established considering the vibrations of coil parameters. The influences of the compensation circuit on the output power and the input impedance are analyzed. The fluctuation of the output power is limited with the circuit parameter optimization. Finally, a 1-kW prototype is built to verily the effectiveness of the proposed approach. Experimental results indicate that within the gap range (20mm~40mm), the maximum fluctuation of the designed system output power is only 4.39% even if the self-inductances vary by 12.33uH and 27.9uH, respectively, and the mutual inductance changes by 1.45 times. Furthermore, the lowest efficiency of the system can reach 91.73%

Under high frequency operating conditions, the resonance of the capacitive power transfer (CPT) system is highly sensitive to parameters, so online tuning is required to maintain the resonance of the system. However, it is difficult to directly obtain the induced voltage on the secondary side of CPT system, so the self-tuning of secondary side cannot be simply realized. This paper proposes a self-tuning method for the secondary side of CPT system using a third pair of decoupled plates and variable inductor. A three-port capacitive coupler with decoupled secondary side is established. A method for judging the resonance state of the secondary side of the CPT system is proposed based on the phase difference detection, and a controller for secondary resonance adjustment based on a variable inductor is carried out. Finally, an experimental prototype was constructed. By adjusting the inductance value of the variable inductor, the equivalent U-I phase difference of the secondary side is reduced from -22.4° to 1.9°, the system output power is maintained at 50W, and efficiency is maintained around 80%.

In the inductive power transfer (IPT) system, a hybrid topology with the anti-misalignment ability and load-independent output is usually used to improve the stability of the system and simplify the control scheme. However, the power distribution of the hybrid topology is uneven with misalignment, resulting in high current stresses in partial coils. In order to minimize the current stresses, a parameter design method with double-sided capacitor-inductor-inductor-inductor-capacitor compensation topology is proposed to optimize the coil currents without the effect on the output fluctuation. Finally, a 3.5-kW laboratory-scale prototype was built to validate the proposed method. The results show that the proposed parameter design method can minimize the maximum current stress significantly, and the hybrid IPT system has good performances of misalignment tolerance and load-independent output current.