Recent years have seen a boom in industries of consumer electronics and electric vehicles. The rapidly growing market requires more advanced technologies to meet consumers’ demands. And the easy charging technology has become a research focus among manufacturers and research institutes.Currently, wired charging is the only charging method for most electronic products and electric vehicles. This kind of charging method requires manual operation, and tends to cause maintenance problems like abrasion, carbon deposition and electric spark, which reduces its reliability in hazardous environment. Instead, wireless charging method can avoid these problems by eliminating cable connection between power source and devices, which makes products safer, more reliable and more flexible.The most matured and widely used wireless charging technology in the market is known as Inductive Power Transfer(IPT). Based on the features and existing problems in this technology, this paper proposes various methods on operation mode, topology and control algorithm to improve the performance of IPT system.Similar to a transformer, IPT technology utilizes electromagnetic induction and coupled coils to transfer power. However, IPT system has its unique transfer characteristics. By analyzing the mathematical model of IPT system, this paper summarized the causes of different transfer characteristics. It should be noted that since the transfer characteristics of the IPT system is essentially decided by the impedence distribution within the system, when it works in overcoupled state, a contradiction occurs between power transfer capability and efficiency of the system.To deal with the contradiction, this paper proposes a switching operation mode for IPT system. The new operation mode is designed based on the transient response of energy transition among the transmitter and receiver resonators. The transfer characteristics of the new operation mode are analyzed with couple mode theory.To realize the proposed operation mode, this paper also proposes a specially designed transmitter circuit and a receiver circuit. The working princepal of the circuits are given, and the waveforms from experiments are analyzed, which validate the whole switch mode IPT system.In addition, to deal with the negative effect of increasing switching loss in high-Q and high frequency system, a pulse power injection technology based DC-AC resonant converter for wireless power transfer systems is proposed. In the proposed circuit, energy is injected into the resonant tank discretely, and wireless energy transfer is performed by free oscillation. The charging process is independent with the oscillation in resonant tanks. During operation, the switch frequency is far less than the frequency of the generated AC current, which effectively reduces the switching loss.Based on the idea of pulse power descrete energy injection IPT inverter, this paper also proposes an AC–AC energy injection resonant converter for wireless power transfer applications, which is based on a bi-directional fly-back converter to inject the energy into a resonant tank discretely. This topology eliminates the DC bus filter in IPT inverter, which reduces the cost and size of the inveter and maintains the advantages of the descrete energy injection IPT system.Finally, to effectively control the time variant, high-order, nonlinear IPT system, the Active Disturbance Rejection Controller(ADRC) is adopted to maintan a constant resonant current in transimitter coil. A simplified modeling method of IPT system is proposed according to the generalized state-space averaging method and the difination of external disturbance in ADRC. Based on the model, ADRC for IPT system is designed. Circuit simulation shows that with the feature of strong robustness, low model dependence and simple operation, ADRC performs a stable and fast control on IPT sytem, which has strong protential for engineering applications. |