Coil misalignment in inductively coupled power transfer (ICPT) systems will lead to fluctuation of transferred power, and even instability of the ICPT systems. To obtain robust control for ICPT system with coil misalignment, a $\mu$-controller based on structured singular value (SSV) is used to set up a closed-loop system in this paper. A generalized state-space averaging (GSSA) model is established using GSSA method first. Then a standard M-$\Delta$ configuration is obtained by a linear fractional transformation (LFT) of the nominal and uncertainty parts of the GSSA model. Finally a $\mu$-controller is designed by D-K iteration. Besides, the theoretical results are validated by computer simulations and practical experiments.

To satisfy independent and controllable power supply requirements for loads with different frequencies and power levels, a multifrequency and multiload (MFML) magnetic coupling resonant wireless power transfer (MCR-WPT) system using hybrid modulation waves sinusoidal pulsewidth modulation (HMW-SPWM) control method is proposed in this article. Based on SPWM, loading a hybrid modulation wave formed by superimposing multifrequency modulation waves to drive the inverter, so the multifrequency hybrid current on the primary side can be obtained. According to the principle of mutual inductance coupling, inductive power with different frequencies is obtained and then separated by multiresonant networks on the secondary side for loads with different frequencies. First, the structure and working principle of a MFML MCR-WPT system controlled by HMW-SPWM are introduced. Then, taking a dual-frequency and dual-load MCR-WPT system as an example, the system is mathematically modeled. Besides, parameters design criteria for reducing interfrequency interference is studied. After that, load characteristics and power factor are analyzed to select appropriate parameters. Furthermore, dynamic characteristics are analyzed. Finally, theoretical results are validated by experiments. The experimental results show that the MFML MCR-WPT system controlled by HMW-SPWM realizes independent and controllable wireless power supply for loads with different frequencies and power levels.

The relay inductively coupled power transfer (ICPT) system is a typical nonlinear and high-order system that is composed of the inverter, the resonant tanks, the relay structure, the rectifier, and the filter. Additionally, the disturbance signals (such as external disturbance) and dynamic perturbations (such as parametric uncertainties) are unavoidable in this system. Therefore, a closed-loop system with an H _∞ controller is designed under the external disturbance and parametric uncertainties in this paper. In order to achieve the robust stability and the robust performance (RSRP) of the closed-loop system with an H _∞ controller, the generalized state-space averaging method is used to establish the linear model of the relay ICPT system first, and a linear fractional transformation of the nominal model and the parametric uncertainties is discussed then. The RSRP of the designed H _∞ controller is tested by the structured singular value. The results of the practical experiment further verify the RSRP of the closed-loop system.

The frequency splitting phenomenon (FSP) is a critical issue in wireless power transfer (WPT) systems. When the FSP exists, the load power will sharply increase and can be dozens of times of the power obtained at the resonant frequency if the driving frequency varies from the resonant frequency, which seriously affects the system safety. This paper studies the impacts caused by the FSP in detail and then proposes a system control method by utilizing the advantages of the FSP to realize constant power output and zero voltage switching (ZVS) of the DC-AC inverter simultaneously. The splitting frequencies are tracked and the driving frequency is precisely adjusted together with the DC-link voltage. The specific implementation method is given in this work to minimize the impacts on the power transfer performance. An 85 kHz, 3.3 kW WPT system is built up to validate the proposed method. The experimental results show that when the FSP occurs at 150 mm coil-to-coil distance and 5 Ω load resistance, the load power can be hold at 3.3 kW with the DC-link voltage reduced from 327 V to 160 V. Meanwhile, ZVS of the inverter is realized and the inverter efficiency is improved from 95% to 97%.

Mid-range wireless power transfer (WPT) system for consumer electronics has been hamstrung by modest energy efficiencies and low misalignment tolerance. As the increase in transfer distance, the increasing leakage magnetic flux between transmitting (Tx) coil and receiving (Rx) will deteriorate the system performance. In this paper, a novel optimization-based design method of passive array coils (PACs) is presented in order to maximize the power transfer efficiency (PTE) and improve the misalignment tolerance in WPT system. A modified multiobjective genetic algorithm is implemented to optimize parameters of PACs in consideration of PTE, displacement flexibility (DF) and volume of PACs. Moreover, a parameter design scheme for compensation network, namely S-Ss-S topology for co-planar multiple coils is investigated, which can achieve zero phase angle (ZPA) in primary side and enhance power factor. Finally, the reasonable prototype of the proposed WPT system with PACs is designed, fabricated and tested. The experimental results show that the proposed structure can increase the efficiency by almost 50% over the system without PACs at 400 mm distance and deliver almost 40 W of output power. Moreover, the PTE and output power can still remain stable under large lateral misalignment with PACs.

The existing simultaneous wireless power and information transmission (SWPIT) technology used for wireless power transfer (WPT) systems is seriously plagued by the interference between the power and information transmission and the complex design of the information transmission and receiving circuits. To combat these problems, this article proposes a novel SWPIT method, which does not need additional information transmitting or receiving coils. The stroboscopic mapping model of the WPT system is established first, and the soft-switching points of the dc–ac inverter are derived and compared for better utilizing deviation frequency enlargement effect (DFEE) to transfer power and information simultaneously. Subsequently, the information detection circuit is designed based on DFEE. The impacts caused by the detection circuit on the power and information transmission are analyzed in detail. Then, the parameters of the detection circuit are optimized for minimizing the mutual interference between the power and information transmission. Finally, a 50 W experimental platform is established to verify the correctness and effectiveness of the proposed SWPIT strategy. The experimental results show that the information transmission rate can reach up to 16 kbps, the load voltage fluctuation can be controlled below 3%, and the efficiency of the whole system can be maintained at 90%.