Investigation of magnetic resonance coupling circuit topologies for wireless power transmission

© 2019 Wiley Periodicals, Inc. Magnetic resonance coupling circuits have four general topologies; however, there is a lack of comprehensive theoretical analysis with experimental verification for each of these topologies regarding their attractiveness for wireless power transfer (WPT). This article provides this for each of the four topologies to fully understand their differences and allow the selection of the most appropriate type based on system requirements. In addition, a problem associated with the resonance coupling method is the phenomenon of frequency splitting, which can lead to a high-power transfer efficiency but low-load power at the resonant frequency. Reasons for frequency splitting and methods of circumventing the problem will be illustrated in this article. Of the four topologies, the series-parallel (SP) (input-output) circuit configuration is the most efficient for the realization of a WPT system with a large load impedance, in terms of achieving both a high power transfer efficiency and high-load power

A Design Method to Minimize Detuning for Double Sided LCC Compensated IPT System Improving Efficiency Versus Air Gap Variation

Inductive power transfer (IPT) technology has garnered considerable attention due to its widespread range of applications. The variation in the air gap can result in variations in the loosely coupled transformer (LCT) parameters, including self-inductance and mutual inductance, due to positional deviations with the ferrite cores on both sides. These variable LCT parameters can damage the resonant tank, ultimately resulting in reduced efficiency. To address this problem, a double-sided LCC-compensated IPT system with a compact decoupled coil is proposed in this paper to improve the system's efficiency with respect to the air gap variation. The key idea is to neutralize the variation in LCT parameters through the use of the self-inductance variation of the decoupled coil so that the detuning degree of the system can be suppressed. Subsequently, the analysis and parametric design process of the system are elaborated. Finally, a 1 kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the efficiency of the system proposed in this work varies from 92.63% to 74.81%, as the air gap increases from 30mm to 90mm, wherein the primary and secondary self-inductance and mutual inductance increased by 19.3% and 135.3%, respectively. Compared with the traditional method, the maximum efficiency improvement is up to 8.16%

Multiphase wireless dynamic charging systems for electric vehicles

PhD ThesisElectric vehicles (EVs) have been intensively developed as an attempt to reduce carbon-dioxide emissions caused by fossil-fuel vehicles. EVs require expensive batteries and power electronics for charging and discharging the battery. Unfortunately, battery technology, such as lithium-ion batteries requires substantial improvements to effectively compete with fossil-fuel cars in price. Also, batteries are usually heavy, take up large space and still have range limitation. Wireless Dynamic Charging (WDC), while the vehicles are in motion, is seen as an alternative to overcome the drawbacks associated with batteries. Due to the continues charging when driving, batteries can become smaller as most of the traction energy comes from the grid directly. WDC is fundamentally developed based on inductive power transfer (IPT) technology, where a time-varying magnetic field is generated by transmitter coils, which are installed underneath the road surface, to wirelessly power receiver coils, that charge the EV’s battery continuously. Presently, there are several technical challenges associated with WDC, which hinders commercialization. The output power fluctuation along the driving direction is one of the most serious problems. These fluctuations cause reduction in constant energy transfer thus requiring larger batteries. Also, batteries lifetime is significantly reduced as a result of increasing internal heating. Several studies attempted to realise constant output power for WDC. However, proposed methods so far, have disadvantages such as high cost, complexity or unable to sustain constant output power throughout the charging process. The work in this thesis proposes a multiphase WDC system to simultaneously achieve constant and high output power for EV applications. The proposed WDC system utilizes multiple primary windings that guarantee a homogeneous mutual magnetic flux for the receiver along the driving direction. This results in a constant induced voltage across the receiver and hence constant output power to charge the EV battery. High output power capability is attained by using multiple transmitter windings arranged in a novel winding method. The effectiveness of the proposed system is analytically described, simulated and demonstrated experimentally using a 3-kW laboratory prototype with the three-phase transmitter. The proposed system requires only simple control, eliminates communications between the primary and secondary sides and delivers 125% higher power transfer capability compared to conventional single-phase WDC systems