Showing papers by "Srdjan Lukic published in 2014"

Reflexive Field Containment in Dynamic Inductive Power Transfer Systems

Abstract: We present a new topology appropriate for “dynamic” wireless charging. Possible applications include charging of electric vehicles or robots moving in a large, predesignated area. We propose a system with a transmitter made from multiple coils commensurable with the moving receiver(s), and powered by a single inverter. The proposed system uses the reactance reflected by the receiver to automatically increase the field strength in coupled portions of the transmitter-receiver system, thus allowing efficient power transfer and adherence to electromagnetic field emission standards without complex shielding circuits, switches, electronics, and communication. The power transfer is at its peak when the transmitting and receiving coils approach their maximum coupling (as defined by the geometrical constraints of the system), resulting in improved system-level efficiency. The presented analysis is supported with simulations and experiments.

Multifrequency Inductive Power Transfer

Abstract: This paper presents a generalized analysis of an inductive power transfer system where multiple frequencies are used to transfer power through the magnetic link. Specifically, we consider a system that amplifies both the fundamental and the third harmonic generated by a full-bridge inverter in order to transfer power to a receiver at both frequencies. The system is analyzed in a generalized manner, by looking at the transconductance function at the transmitter and the receiver for each of the harmonics. Using this approach, the emitted field strength, inverter losses, combined transmitter and receiver coil conduction losses, and VA ratings are compared to a reference single-frequency system. The analysis shows that the dual-frequency system can outperform the single-frequency equivalent for all metrics considered; however, in practice, a tradeoff between the performance criteria is necessary, since the optimal operation points for each criterion cannot be attained with a single design.

Closed-Form Expressions for Minimizing Total Harmonic Distortion in Three-Phase Multilevel Converters

Abstract: The total harmonic distortion (THD) of a waveform is a standard way to quantify its deviation from a sinusoid. In three-phase systems, we are interested in minimizing 3THD: the component of THD produced by odd nontriplen harmonics. However, its definition involves an infinite sum, making it difficult to evaluate and analyze. This paper solves the problem of finding equivalent closed-form expressions for the 3THD of a staircase waveform. In particular, two expressions are rigorously derived, which reveal 3THD to be a piecewise differentiable function. One expression is shorter but describes the pieces implicitly. The other is longer but describes the pieces explicitly. We minimize 3THD using the closed-form expression and provide a comparison with previous techniques. Finally, we provide experimental results that show close agreement with the theoretical results.

Optimization of foil conductor layout in inductive power transfer system resonators

Abstract: Proper use of winding area and conductor layout in resonating coils of Inductive Power Transfer (IPT) systems is of great importance to achieve high efficient systems. In this paper a simple adaptable analytical method is investigated that can be implemented on variety of coil layout optimization problems to increase the resonator performance and the system efficiency. The method is frequency independent and overcomes the difficulties associated with the prediction of high frequency field distributions in IPT systems. In this study the procedure is applied to optimize a one-turn circular foil resonator operating at 13.56 MHz, with the Finite Element (FE) results showing of up to 30% increase in resonator quality factor and 1.73% increase in link efficiency of the IPT system.

Modular design of cascaded H-bridge for community energy storage systems by using secondary traction batteries

Abstract: This paper proposed a Community Energy Storage System (CES) by using reclaimed tractions batteries. The cascaded H-Bridge topology is selected for this application after reviewing all possible solutions. Control strategies to have independent control of each H-Bridge are reviewed and existing control strategies are all centralized control. To have modular design and independent control of each module, a new control strategy is proposed for cascaded H-Bridge converter. With this control strategy, each H-Bridge module will have its own controller and there is no connection between the controllers. All the control strategies are implemented in the local controllers and no central controller is needed. A small scale CES system is built to verify the proposed control strategy with great success.

Systems and methods for wireless power transfer

Abstract: Disclosed herein is a power transfer system. The power transfer system includes a receiver configured to wirelessly receive power for powering an electronic device, a power source, and at least one transmitter operably coupled to the power source for wirelessly transferring power generated by the power source. Wherein when the at least one transmitter is operably coupled to the receiver, the power source and the at least one transmitter operate together in a first mode such that the power source generates power at a first level and the at least one transmitter transfers the generated power to the receiver. Wherein when the at least one transmitter is not operably coupled to the receiver, the power source and the at least one transmitter operate together in a second mode such that the power source generates power at a second level lower than the first level or equal to zero and the transmitter does not wirelessly transfer power.