A controller for output voltage and power regulation is important for the wireless charging system. For the controller design, it is crucial to establish the accurate system model with considering the time delay, as high time delay exists due to wireless communication, data sampling, and processor calculations for a practical wireless power transfer system. Presently, the common modeling methods, such as the coupled-mode method are based on circuit theories and the component parameters. However, the exact parameters are hard to get due to the diversity of the equipment and application scenarios. Especially, the circuit theories modeling cannot deal with the time delay from hardware limitation and wireless communication. Alternatively, a data-driven modeling method based on the simplified refined instrumental variable method is proposed in this article to get the control-oriented model with time delay. Moreover, based on the estimated model, a controller based on the internal model control is designed to regulate the output voltage. It is shown that the models obtained based on different sampling times are able to accurately describe the system dynamics and the controllers designed based on them are able to achieve the desired control performance.

This paper develops a method of input design for the identification of wireless power transfer (WPT) systems based on receding horizon D-optimization. The dynamic behavior of the system is characterized by a discrete-time, Single-Input, Single-Output (SISO) model, and the associated model parameters are estimated by a recursive least-squares method. To improve the quality of the parameter estimates, the excitation signal of the system is designed based on receding horizon D-optimization. To improve the convergence and efficiency of the input design process, the Sequential Quadratic Programming (SQP) method is employed to solve the receding horizon D-optimization. Numerical and experimental results are presented to demonstrate the effectiveness of the proposed method.

In the field of control-oriented modeling of wireless power transfer (WPT) system, it is urgent to establish a simple model to reflect the nonlinear characteristics introduced by phase-shift control methods, which is significant to the design of controllers. Due to the nonlinear nature introduced by phase-shift control, controllers designed based on specific steady-state small-signal models struggle to maintain closed-loop dynamic performance. In this article, the nonlinearities of the WPT system are implicitly considered by using the Hammerstein model-based identification (HMI) method, so the accuracy of the identified model is guaranteed even if the working point changes, which is unique advantage compared with other methods. In particular, an uncertainty model is precisely established via a frequency-domain analysis approach to introduce the nonlinear characteristics and the statistical properties of identification into the H $\infty$ control problem, which maintains the robustness of closed-loop WPT system. Finally, an experiment is given to verify the effectiveness of HMI method and proposed H $\infty$ robust controller.

A high-power inductive power transfer system with overlapped transmitters driven by a multi-inverter topology is proposed in this article. Each inverter drives an independent primary coil to transfer energy to the common secondary coil. A phase-shifted control strategy at inverter-level is proposed to regulate the output of the system. A dynamic model based on virtual resonant loop is proposed to describe the system with the phase-shift angle and the output voltage as the input and output variables, respectively. With the introduction of virtual resonant loop, n practical resonant loops at the primary side can be expressed by two equations, which greatly reduce the scale and order of the model. A PI controller is developed to evaluate the system regulating performance. A laboratory prototype driven by three inverters connected in parallel was built to verify the theoretical analysis. Experiments have shown that the setting times were within 13 ms under load resistance and reference disturbances, which verified the validity of the model and the controller.

Spatial acoustic radiation characteristics analysis is the precondition of reducing the noise influence of outdoor power transformer while multi-physical field coupling method can be applied to quantify and reveal these acoustic characteristics of a running power transformer. In this study, based on the theoretical analysis about noise generation and dissemination process, an acoustic radiation model about oil-immersed power transformer was established and verified with field test data in time and frequency domain. Then, far-field analysis and directivity analysis were accomplished to characterize acoustic field of power transformer under multiple operating conditions. Finally, the acoustic radiation influence on potential surrounding buildings were analyzed and discussed. The visual results and conclusion provide acoustic guide for the optimal planning and design about both power substation and ambient buildings.

Wireless power transfer system (WPT) is an interesting alternative for charging electric vehicles and has a broad prospect in public transport applications. In order to obtain optimal power transfer, the existing WPT systems often require perfect alignment between the primary and secondary coils, which can hardly be met in real applications. To relieve this problem and achieve the goal of free positioning, a one-to-multiple WPT topology being able to improve the misalignment tolerance at secondary side is proposed in this letter. Based on circuit analysis and Matlab simulation, a mixed mode is proposed to obtain a steady power transfer with horizontal misalignment. To verify the proposed topology, a one-to-two WPT system with a three winding transformer is developed in this letter, showing that proposed topology with the mixed mode can significantly increase the positioning adaptability.