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Passive diode bridge rectifier with LC filter is widely used in wireless power transfer (WPT) system due to its simple structure and uncontrolled characteristics. However, as the load resistance decreases, its input phase angle will also decrease rapidly until it shows obvious capacitive. Therefore, a novel rectifier topology with an input-series inductor (hereafter called ISIR) is proposed in this article to solve this problem. What is more, the ISIR can avoid the duty cycle loss and improve the dc–dc efficiency. First, the mechanism of ISIR is analyzed in detail combined with the operating status of topology. Then, the inductance and compensation parameters are determined based on theoretical calculation and simulation results. Finally, a prototype with a maximum load of 7 Ω is built to validate the feasibility and effectiveness of ISIR, and 88% efficiency is achieved under this condition. Compared with the traditional method, it has increased by 1.05%. The maximum efficiency of WPT system is as high as 91.14% with the proposed ISIR. [ABSTRACT FROM AUTHOR]

Inductive power transmission has been applied in industries, such as electric vehicles, consumer electronics and biomedical fields. However, there is a long-term key problem in this field that has not been solved. This is the adverse effect of the parasitic capacitance of the coil, which will cause the change of the coil inductance, the reduction of the quality factor and the reduction of efficiency. Especially in the field of long-distance wireless power transmission. The existing technologies all adopt the scheme of sacrificing volume in exchange for the quality factor of the coil. As a result, the volume of the system is very large, and the quality factor of the coil is still not high enough because the influence of parasitic capacitance has not been completely eliminated. Here, we found the solution. Connect compensation capacitors in series to the coil sections to short-circuit the parasitic capacitance and reduce its loss. The designed system has a diameter of 502 mm and a thickness of 22 mm, which can transmit 115.2 W of power within a distance of two meters with an efficiency of 29%. [ABSTRACT FROM AUTHOR]

Wireless power transmission technology is used to transmit energy without contact in the field of electric vehicles, consumer electronics, and other industries. Among them, there are some applications with very low coupling coefficient where multilayer coil needs to be wound. Influenced by the parasitic capacitor between layers, the loss of the multilayer coil increases. The improved coil winding method and compensation method are proposed in this letter. Winding coils following the same sequence from outside to inside in each layer and connecting capacitors in series between layers of the coil can significantly reduce the voltage of the layers’ parasitic capacitor, which will decrease the coil loss. Compared with traditional method, the improved method increases the system efficiency at heavy load and light load by 0.74% and 2.48%, respectively. A 1-kW prototype was built with the maximum efficiency of 93.58%. [ABSTRACT FROM AUTHOR]

The capability of misalignment tolerance is vital for an inductive power transfer (IPT) system. In this article, a new loosely coupled transformer (LCT) structure with series solenoid and DD pads (SDDP) is proposed to improve the misalignment tolerance of the IPT system. The designed LCT not only has strong misalignment-tolerant capability in the X-direction but also has strong misalignment-tolerant capability in the Y-direction. The fluctuation of mutual inductance is 3.15% within 67.0% misalignment distance of the largest size of the SDDP in the X-direction and 44% misalignment distance of the largest size of the SDDP in the Y-direction. Finally, an LCC/S compensated IPT system with 300 W power is built as an example to demonstrate the performance of the proposed LCT. The output voltage fluctuates with the rated load, which is less than 3.2%, and the efficiency is 90.2–91.3%. [ABSTRACT FROM AUTHOR]

With the increase of load resistance, the impedance angle of the rectifier with passive C filter also increases, which may have some negative effects on the characteristics of the inductive power transfer (IPT) system. This article presents an impedance analysis method for C-filter rectifiers in continuous conduction mode. The calculation formula of critical load resistance is given and the relevant values are calculated. An improved C-filter rectifier circuit is proposed to reduce the phase angle of the IPT system. A very tiny capacitance is connected in parallel at the input end of the rectifier to reduce the impedance angle as load resistance changes, with hardly increased costs. This improved method not only improves the system efficiency, but also reduces the fluctuation of output voltage or current. Simulation and experiment results verify the feasibility of the proposed topology. A 1 kW prototype with primary series, secondary series compensation topology was built. The maximum system efficiency from dc power supply to the load is 94.5%. The efficiency under rated load is as high as 93%. Compared with traditional method, it has increased by 0.6%. [ABSTRACT FROM AUTHOR]

The capability of misalignment tolerance is vital for an inductive power transfer system. The conditions satisfied by the high-misalignment-tolerant compensation topology are proposed in the article. It is proven that all compensation topologies with secondary parallel compensation component have a strong capability of misalignment tolerance if the parameters of the compensation circuit are properly designed. And, their misalignment-tolerant capability was analyzed. The impedance characteristics of the simple S/T compensation topology are analyzed. Two prototypes of approximately 300 W used S/SP (primary series, secondary series–parallel) compensation topology with strong misalignment tolerance were designed to verify the system performance. They have the characteristics of constant-voltage and constant-current output, respectively. [ABSTRACT FROM AUTHOR]

A three-stage-five-coil inductive power transfer (IPT) system which is based on cylindrical solenoid coupler (CSC) is proposed in this article. The shape and parameters of the CSC are optimized. The five litz coils compensated by series capacitors are considered to form an IPT system based on equivalent CLC/S/CLC compensation topology with constant voltage characteristics. The mutual inductance between compensation auxiliary coil (CAC) and power transfer coil could be changed by moving the position of CAC, and the freedom of parameter design is enhanced. Mathematical model and loss model of the system are established, and power transfer characteristics of the system are analyzed. The system is considered to be used as a power source for state detection equipment of high-voltage (HV) device to achieve long-distance IPT, the effect of the coupler on the HV electric field is verified. Finally, a prototype with a length of 1.54 m was built. Based on the platform, output voltage and dc–dc power transfer efficiency curves with changed input voltage and load are obtained. The maximum efficiency of the dc–dc system can reach about 60%. [ABSTRACT FROM AUTHOR]

In this article, a 2.5m five-stage inductive power transfer (IPT) system based on domino cylindrical solenoid coupler (CSC) compensated, respectively, in layers is proposed. The system is considered to be used as 220 kV post insulators application, transferring power for sensors and measuring instruments of smart grids. The distributed series compensation method is applied to double-layer CSC. Compared with the two types of parallel schemes, this method can significantly reduce the current of the main circuit. Compared with the concentrated series compensation method, this method can effectively reduce the resistance caused by the stray capacitance. The interaction between the post insulator and the magnetic coupling structure is analyzed. The circuit model of the system with constant voltage output characteristics is analyzed. A prototype with a maximum efficiency of 66.7% is built. When the power is transferred to a larger value of 77.8W, the efficiency can still reach 62%. Comparing with previous works, the wireless distance is extended while the efficiency is improved. [ABSTRACT FROM AUTHOR]

In this article, a shielding scheme based on ferrite magnetic antennas (SS-FMA) is proposed. The scheme can effectively provide a path for the magnetic field lines of three-dimensional couplers to be concentrated and conducted. The SS-FMA is considered to be applied for long range inductive power transfer (IPT) systems of post insulators to powering smart grid sensors and improve the efficiency under the influence of metal components. The negative influence of the aluminum flanges on the magnetic field distribution is analyzed. The suppression effects of the shielding scheme on the abovementioned influence have been analyzed. Parameters of the SS-FMA are optimized. The equivalent circuit model is established, and the abovementioned process is explained from the perspective of the circuit model. A prototype of a post insulator that includes IPT system and SS-FMA has been built. When the coils of the IPT system are attached to the flanges, the efficiency can still reach 47.8% under the influence of SS-FMA, which is an increase of 13.7% compared with no shielding scheme. When the coils are slightly away from the flanges, efficiency of the system including SS-FMA can be quickly improved to 54.3%. [ABSTRACT FROM AUTHOR]