This paper studies the model for the three-phase contactless power transfer system. A phase winding in the three-phase contactless power transformer has the magnetic couplings with all of the other phase windings. Moreover, the magnetic couplings depend on the displacement of the secondary armature with respect to the primary armature. The equivalent model of the three-phase system with the complicated mutual inductances due to such magnetic couplings is presented. The model is transformed into the single-phase model that is similar to the model for the conventional system. The simplified model allows the easy consideration of the operation of the three-phase system. By using the model, the resonant capacitances for the three-phase system are available. The model is confirmed to successfully simulate the performance of the actual system. In addition, the experimental and theoretical results confirm that the three-phase system has the stable performance of the power transfer independently of the displacement of the secondary.
"Three-phase resonant inverters are widely used in industrial applications. Such applications include high power DC-DC converters, contact-less power transfer systems and multi-phase induction heating systems             . "
[Show abstract][Hide abstract] ABSTRACT: This paper presents a new tuning loop for three-phase current source parallel resonant inverters. The switching frequency is tuned by using a phase-locked loop (PLL) circuit based on a new Phase Detector (PD). In practice, the resonant capacitors and inductors have tolerances that cause different resonant frequency for each phase. This paper shows that a conventional PD causes higher voltage stress over switches and DC-link inductor. In the proposed tuning loop, the PLL tracks the average value of the resonant frequencies that reduces the voltage stress. In addition, there is no feedback from the load currents to detect the phase error, which is another advantage of the new method. A laboratory prototype of a three-phase current source parallel resonant half-bridge inverter was built to verify the advantages of the proposed tuning system with operating frequency of 22 kHz.
[Show abstract][Hide abstract] ABSTRACT: This paper reports the characteristics of planar contactless power transfer systems, which are classified into the following types: single-phase primary and single-phase secondary system (SS system), three-phase primary and single-phase secondary system (TS system), and three-phase primary and three-phase secondary system (TT system). The SS system is used in conventional contactless power transfer. On the other hand, in the last few years, the TS system has been studied more. As a novel system, the TT system is here proposed. The characteristics of all three systems are measured by using a common experimental prototype made of printed circuit board. The comparison confirms that the TT system has higher efficiency and can output uniform power independent of the secondary position, as compared to the other systems.
IEEE Transactions on Power Electronics 06/2012; 27(6):2980-2993. DOI:10.1109/TPEL.2011.2178434 · 6.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Most problems related to contactless energy transfer are usually dealt within the framework of transformer theory, employing equivalent electric circuits as a tool for their analysis. Here, however, a physics approach based on the Maxwell equations is followed. Electric and magnetic fields are utilized to evaluate the Poynting vector, which defines the direction and power density carried by the electromagnetic field. The concepts of magnetic voltage and magnetic flux are utilized to define the instantaneous power guided within the magnetic transmitter. Contactless energy transfer requires two separate parts, a transmitter and a receiver circuit. In this paper, we pay attention to the electromagnetic field guided and emitted by the transmitter; internal skin effect (eddy currents losses) is accounted for; electromagnetic energy leaving the transmitter is evaluated using short-dipole antenna theory. This paper does not offer a new practical application of contactless energy transfer. Its scope is rather different; its aim is to provide a fresh look on contactless energy transfer in the context of an electromagnetics framework.
IEEE Transactions on Power Electronics 10/2012; 27(10):4292-4300. DOI:10.1109/TPEL.2012.2191421 · 6.01 Impact Factor
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