The crescent interest in greener transportation systems increases the search for coherent, intelligent, efficient and more cost effective solutions. In this scenarios Light Rail Transits are becoming more and more used. In the direction or more flexible and safer system, contactless power systems are being used in LRT. This paper present an Improved core shape for the contactless transformer used in a model LRT system. The electrical and the magnetic analysis of the transformer are performed and compared to a Planar core transformer. The Improved core allows to suppress the utilization of core in the secondary reducing the weight in the train car with keeping the required transmitting power and input voltage.
This paper presents contactless power supply systems using Valtchev model in transportation systems. The major drawback of contactless systems is that the efficiency is lower than that of contact systems. The coupling coefficient of the contactless transformer is the most influent parameter on the system efficiency. Here, a new computer model for the contactless transfer system developed in the Korea Railroad Research Institute is present. Also, simulations of the old model and the new model are compared with the prototype measurement to assure the model validity.
-Contactless systems use electromagnetic fields to transport power from railway substation to the traction system. The proto type of inductive power transfer (IPS) system has been developed in order to use train power feeding. It is based on a contactless transformer with a fixed coreless primary and different secondary core like E shape and U shape. The primary coil is supply with 50 kHz current which produces a magnetic flux in the secondary core. Further this flux induces a current in the secondary coil. This paper presents results of experiment for developed inductive power transfer system experiments. The IPS has a large air gap, so it is required a high magnetization current and compensate the leakage flux of primary and secondary coil. The proto type IPS has an air gap with range 1 to 5 mm and core material is ferrite with maximum power of 5 kW. The power supply to IPS is designed by constant current control inverter with compensation capacitance. We measure inductance of IPS and coupling coefficient in order to calculate the compensation parameter according to variable air gap. The analysis of output for the proto type IPS is performed regarding different loads.
Utilization of wireless power transfer in light rail transits is seen as one solution for electrification of lines. The main advantage of this supply system is the reduction of installation; moreover, the alignment between the transmitter coil in the track and the receiver coil in the train should be perfect in order not to affect the power transfer. To reduce the effects of misalignment on the input and output electric parameters of the system, a new planar core and coil design, called hybrid intercore coil, is proposed. The proposed design uses a magnetic material layer between the windings in the inner half of the coil to create a non-uniform magnetic field distribution, which makes the system more robust against the effects of coil misalignment on the system current and voltage. Simulations with finite element method software were conducted to compare designs. The results show that the proposed design is less susceptible to the effects of misalignment and is more efficient. Prototype cores were constructed to verify the simulation results. Measurements show a smaller input overcurrent and output overvoltage when operating in resonance mode. The proposed design reduced the effects of coil misalignment on electrical parameters.
This paper proposes two different types of core shape analysis for contactless transformer, which can be used for delivering high-power to traction in new railway systems. This type of railway system without catenary can save construction cost and maintenance costs. The major problem of contactless transformer is the air gap between the primary side and secondary side, which affects the power delivery. To enhance power delivery, the proposed shapes are installed and tested for with prototype. The two results are compared by the measurement of the self-inductances, mutual inductances and the coupling coefficient, with the analysis of the assembly process.I.
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