The promising element of the infrastructure of unmanned electric vehicles is Wireless chargers. The central part of such systems is a resonant circuit that provides Wireless power transfer. The article discusses a set of criteria used for making the rational choice of the resonant circuit parameters. Such criteria include the efficiency, the current transfer coefficient, the excess voltage on the resonant circuit capacitors over the input voltage, the ratio between the transmitting circuit current and the receiving one. For the resonant circuit with fixed coils size and fixed resonant frequency, the families of curves were obtained via parametric analysis to show how these criteria change depending on the inductance and capacitance of the resonant circuit. The obtained dependencies allow choosing the rational inductances and capacitances of the resonant circuit, providing for a given size and a given value of the input voltage the highest conveyed power with the highest efficiency at the minimum voltage class of capacitors and the minimum current of semiconductor switches. The results of the parametric analysis were confirmed experimentally.

Non-radiative Wireless power transfer systems based on magnetic resonant coupling have received the attention of many researchers, due to their high efficiency over distances greater than the diameter of their coils and their mid-range of operations. In this article, the design and implementation of a 4-Wireless power transmission system consisting of a power coil (drive loop), a transmitting coil (Tx coil), a receiving coil (Rx coil) and a load coil (load loop) is presented. power is transmitted when the frequency of the E class amplifier is equal to the self-resonant frequency of the transceiver coils. The purpose of this paper is to achieve the highest efficiency without designing an additional impedance matching system. This condition is achieved by varying the coupling factor between the power coil (load) and the two resonators. The maximum efficiency is 93% at 15 cm and using this method results in efficiency improvements of 56. 3% and 35. 6% at the distances of 60 cm and 100 cm respectively, compared to the case of the coils being fixed.

Background and Objectives: Today, replacing gasoline-powered vehicles with electric vehicles (EVs) and connecting them to an electric power source have made the optimal usage of energy-saving resources. Therefore, Wireless power transfer (WPT) outstands as an alternative technology to improve the user perception about the charging process of the EVs. Superconducting coils (SCs) with high-temperature have an applied feature in decreasing losses of Wireless power transmission (WPT). The Magnetic force has effects of overall deformation modes between two current carrier superconducting coils, i. e. axial extension, torsion, and bending. Coil misalignment is a fundamental problem and its impact on Wireless power transmission efficiency is very complex. The analysis of a magnetic force which is presented in this paper are beneficially for the design and application of the WPT systems. Here, a fast analytical solution is presented to obtain the magnetic force between the transmitter and receiver helical superconducting coils in different positions. Methods: In this paper, a new method applied to solve the numerically magnetic force solutions in different superconducting coils mismatch states for WPT. Finally, for improvement of efficiency, the WPT system has been designed on the basis of mutual inductance changes which receiving helical coil was moved inside the transmitting helical coil. Hence, the magnetic force calculation of movable YBCO superconducting helical coils inside each other is presented. These models have been compared with the FEM. Results: Results show that the presented equations are reliable as well. According to the comparing the analysis and FEM data, the obtained results indicated the errors with less than 0. 0064%. Also, results show an excellent agreement with respect to the finite element method. Conclusion: In this paper, the numerical solutions of magnetic force in different superconducting coils mismatch states were solved by a new method. The magnetic force analysis basics introduced in this paper are useful to develop and apply for Wireless power transmission system. The simulation results show that only by applying some constraints, the efficiency of the transmitted Wireless power will be optimized. Then, analytical models have been presented which make it possible to calculate the axial force which was exerted between two axially Helical magnetized and two thin coils in air. Also, the analytical stiffness calculation applied between these distributions of magnetic source has been presented. These models have been compared with the FEM to show an appropriate consistency.