Accurate and fast identification for mutual inductance and load charging parameters of inductive wireless power transfer (IPT) system is essential for impedance matching, and the output control of communication-free IPT system. A joint real-time identification method for mutual inductance and load charging parameters of IPT system is proposed in this paper. Only via measuring the RMS value of fundamental voltage and current on primary side, the double equivalent impedance modulus equations about mutual inductance and equivalent load resistance are established. To obtain real-time identification results of mutual inductance and equivalent load resistance from the high-order implicit function equations, an improved adaptive filtering algorithm based on Least Mean Squares (LMS) is proposed. Then, the identification values of load charging parameters are obtained according to the identified mutual inductance and equivalent load resistance. Finally, a 3.6kW platform is built to verify the validity of the proposed method. And the experiment results show that, compared with other existing achievements, the proposed method can identify U_Bat , I_Bat , R_L and M simultaneously in real-time without changing the system operation, and it has faster rate and higher accuracy of identification.

Inductive power transfer (IPT) technology is widely used because of its high convenience especially for charging of electric vehicles. It has remained a high failure rate in recent years due to the large number of semiconductor components they contain. In this article, to address the problem that rectifier with constant-current output characteristics in the IPT cannot occur to open-circuit fault, a rectifier protected method based on SS type IPT system is designed. First, the hazards and impacts on the system after a diode fault are analyzed. Then, a method for parameter design of protective devices have developed that does not affect the compensation parameter design of the original system, which maintain high efficiency operation after open-circuit fault, and a fault detection technology based on dc bias of the fault eigenvalue is proposed. This article solves the problem that the rectifier cannot be open-circuit faulted of the traditional IPT constant-current topology, which improves the reliability and safety of the system. Finally, experiments under different loads verify that the system rectifier can maintain an operating state with an efficiency of 91.78% after a diode open-circuit fault occurs, as well as the accuracy of the fault detection method.

The control strategy based on parameter identification is a preferred scheme for constant-current (CC) and constant-voltage (CV) charging control of the communication-free inductive wireless transfer system, which is studied and discussed in this article. First, a multiparameter real-time identification method is introduced in detail, which is the basis of this study. Then, two control strategies based on the aforementioned identification method are proposed. One of them is the control strategy based on the PID controller and the identification results of charging information, and its working principle is described in detail. The other is a novel control strategy based on a fast calculation of the conduction angle. The conduction angle calculation process is deduced, and the working principle for CC and CV charging control is provided in detail. Experiments are carried out on a 3.6-kW prototype, and the experimental results show that both the two proposed control strategies can realize the CC and CV charging control effectively, and their response time is shorter than that of the control strategy based on wireless communication. Moreover, the control strategy based on fast calculation of conduction angle has better control performance than the PID-based control strategy because it omits the complicated design process of the controller and saves the dynamic adjusting time that the controller needs.

H∞ control can guarantee the performance of a nominal ICPT system. However, the dynamic performance may suffer degradation when the parameter deviates from its nominal value. Thus, to enhance the overall dynamic performance of the ICPT system under parameter perturbations, an H∞ control method with a selected weighting function considering parameter perturbations is proposed in this article. First, a generalized state-space model is established to analyze the influence of parameter perturbations on the open-loop system in detail. After that, an uncertain model is established via frequency-domain analysis, generating a numerical solution of a weighting function used to describe the parameter perturbations. Then, the generalized plant with uncertainty is obtained and transferred into a standard H∞ optimal problem via small gain theory. Based on the proposed controller, the dynamic performance and robustness of the closed-loop system are analyzed and verified theoretically. Finally, simulation and experimental results further verify that the proposed H∞ control method can make the closed-loop system obtain good dynamic performance and strong robustness against parameter perturbations. The settling time is less than 6.8 ms without any overshoot when the system suffers parameter perturbations. Besides, the controller can maintain good dynamic performance in the startup and reference tracking experiments.

Nowadays, a higher capability of voltage and power is needed in scenarios such as shore-based power system and electric vehicles charging. ISOS multi-channel inductive power transfer (IPT) system, due to its flexibility and reliability, has become a promising way. To get a more generalized realization of the proposed system, the effect of cross coupling is analyzed theoretically and corresponding elimination method is proposed in this paper. Firstly, a numerical expression to describe the input impedance of each channel is figured out and the influence of cross coupling is analyzed. It shows that cross coupling causes difference in phase angles of input-impedance among different inverters, which produces a strong output inconsistency among channels, especially under large-load condition. Then, to eliminate the harmful effect of cross coupling, a parameter design principle is proposed based on the equivalent impedance compensation without any additional circuit components or control loop. Finally, a 2.81kW down-scale 3-channel prototype was built to confirm the effectiveness of the proposed principle. As the experimental results show that the phase-angle imbalance of the compensated system gets eliminated with the maximum difference being just 2.3°, which makes the channels get equivalently decoupled from each other and the system easier for implementation.

To realize high-voltage high-power wireless power transfer, an input-series output-series (ISOS) multi-channel IPT system is proposed in this paper, which is well suited for high-voltage load and can reduce the transmission loss at the input side. Meanwhile, the number of channels can be adjusted flexibly according to the voltage and power requirement. Firstly, the transmission characteristics of the proposed system is analyzed based on different compensation networks. Then, possible factors that may lead to voltage imbalance are analyzed. The numerical relationship of voltage ratio and parameter offset ratio between different channels is figured out and an improved voltage sharing principle based on fixed-ratio phase-shift control is proposed. Finally, two down-scale prototypes composed of 2 channels and 3 channels are built up to confirm the effectiveness of the proposed topology and voltage sharing method. The experimental results show that the proposed method can achieve effective voltage sharing under parameter deviation. The output power and voltage of 2-channel system can reach to 9.0474kW and 604.82V with the DC-DC efficiency being 94%. As for the 3-channel system, the outputs get increased to 13.581kW and 903.3V with the efficiency maintaining 94%, while the input and output currents remain almost unchanged compared to 2-channel system.