Chun-Taek Rim

Narrow-Width Inductive Power Transfer System for Online Electrical Vehicles

A new inductive power transfer system with a narrow rail width, a small pickup size, and a large air gap for online electric vehicles is proposed in this paper. By introducing a new core structure, the orientation of the magnetic flux alternates along with the road; hence, an inductive power transfer system with a narrow rail width of 10 cm, a large air gap of 20 cm, and a large lateral displacement about 24 cm was implemented. The resonant circuit of the inductive power transfer system, driven by a current source, was fully characterized. The experimental results showed that the maximum output power was 35 kW and that the maximum efficiency was 74% at 27 kW. The proposed system was found to be adequate for electric vehicles, allowing them to drive freely on specially implemented roads by obtaining power from the buried power supply rail.

On-Line Electric Vehicle using inductive power transfer system

In this paper, 3 generations of OLEV (On-Line Electrical Vehicle) are introduced. The 1st generation of OLEV is conventional E-type structure. The air gap of the 1st generation is 1cm and the input to output power efficiency is 80% with 3 kW output power. The ultra slim U-type mono rail structure is applied to the 2nd generation of OLEV. This structure is applied to the OLEV bus which achieves 52 kW output power with 72% efficiency at 17 cm air gap. SUV (Sports Utility Vehicle) equipped with the 3rd generation of OLEV named ultra slim W-type (dual rail structure) accomplished 15 kW/pick-up and 71% efficiency at 17 cm air gap

Phasor transformation and its application to the DC/AC analyses of frequency phase-controlled series resonant converters (SRC)

A novel modeling technique based on phasor transformation that provides a unified model of series resonant converters (SRCs) is proposed. The approach gives explicit and simple equations that provide fruitful physical insight. When the switching frequency deviates from the resonant frequency, a first-order SRC model is obtained, and in the case of resonance a second-order model is obtained. It is shown that the frequency band of the second-order model is very narrow in practice. The time constant, small-signal gains, and system order are highly dependent on the switching frequency, load resistor, and output capacitor. >

Transformers as equivalent circuits for switches: general proofs and D-Q transformation-based analyses

The equivalent circuits for the switches in DC-DC, DC-AC, AC-DC, and AC-AC converters are proved to be time-varying transformers. This result is used in the analyses of DC-DC converters, an eight-order current source rectifier-inverter, and a buck-boost inverter. The circuit D-Q transformation is proposed for the analyses of the AC converters such as inverters, rectifiers, and cycloconverters which include the time-varying transformers. Gyrators appear in the D-Q transformed inductors and capacitors of the AC converters. Few equational manipulations are required to determine the steady-state operating points and the small signal gains of the converters. The analysis result for the rectifier-inverter shows that the circuit has self-short-circuit protection capability and strong immunity in the parasitic inductor resistance. >

Dynamics Characterization of the Inductive Power Transfer System for Online Electric Vehicles by Laplace Phasor Transform

A large-signal dynamic model of the inductive power transfer system (IPTS) for the online electric vehicle (OLEV) is developed using the recently proposed Laplace phasor transform. With the help of this dynamic model, the effect of the output capacitor and load resistance variation on the transient response of the IPTS is analyzed. The maximum pickup current and output voltage for an abrupt in-rush of the OLEV are examined by both the proposed analysis and simulations, and verified by experiments with good agreement. Thus, it is found that the voltage and current ratings of the pickup remain relatively constant regardless of the load resistance.

High performance inductive power transfer system with narrow rail width for On-Line Electric Vehicles

A new inductive power transfer system (IPTS) with narrow rail width and large air-gap for electric vehicle (EV) is proposed in this paper. By a new core structure, the orientation of magnetic flux is alternating along with the road. Hence, the proposed IPTS with narrow rail width, 10 cm, and large air-gap, up to 20 cm, can be implemented for EV. The power supply inverter uses 440 V, 3phase input and supplies 20 kHz output current. To null the high voltages of power rail and pick-up and to transfer maximum power to vehicles, resonant capacitors are inserted to each side of the rail and the pick-up. The test results show that the maximum output power is 35 kW and the maximum efficiency is 74 % at 27 kW output. The proposed IPTS is found to be adequate for EV which can freely drive on the road by picking up the power from the underground power supply rail.

New Cross-Segmented Power Supply Rails for Roadway-Powered Electric Vehicles

New cross-segmented power supply rails for roadway-powered electric vehicles are proposed in this paper for reducing construction cost and EMF. The proposed rail consists of two pairs of power cables, core, bidirectional power switches, a transformer, capacitors, and harness. Each rail is connected through a switch box, which can change the current direction of a pair of power cables. Hence, adding the current of the two pairs of power cables results in the activation mode while nullifying it does the silence mode. A coupling transformer with two capacitors is introduced to compensate the variable line inductance of the rail due to the change of current direction. Therefore, multiple rails can be concurrently activated by selective turning-on and turning-off the power switches using an inverter. In addition, the EMF for the silence mode is drastically reduced if a twisted pair of power cables and copper nets is used, so that the ICNIRP guideline 6.25 μT at 20-kHz operating frequency can be met. The proposed cross-segmented power supply rail was implemented for experiments and verified for practical applications.

Characterization of novel Inductive Power Transfer Systems for On-Line Electric Vehicles

The Inductive Power Transfer System (IPTS) for On-Line Electric Vehicle (OLEV) developed at KAIST is fully characterized in this paper. The proposed IPTS includes Teslas resonant transformers and show quite different characteristics comparing with conventional transformers. A current source instead of a voltage source is used for the IPTS at the primary side, and the system is fully resonated for maximum power delivery unlike other IPTSs. The proposed IPTS inherently has novel input/output characteristics. It is quite robust to abrupt the load change raised by the vehicle inrush or power fluctuation. Furthermore the output voltage of the IPTS is nearly constant regardless of output power, and the output current may increase regardless of source current. It is shown in this paper that the IPTS is equivalently an ideal voltage source, hence the output current can be infinite theoretically. The limiting factors in practice are found to be the resonant frequency variation and the parasitic resistances. It is thoroughly verified by simulations and experiments.

A complete DC and AC analysis of three-phase controlled-current PWM rectifier using circuit D-Q transformation

A recently proposed circuit P-Q transformation is used to analyze a three-phase controlled-current PWM rectifier. The DC operating point and AC transfer functions are completely determined. Most features of the power converter are clearly interpreted. They are: (1) the output voltage can be controlled from zero to maximum; (2) the system is equivalently an ideal current source in the steady state; (3) the system can be described as linear circuits; and (4) the input power factor can be arbitrarily controlled within a certain control range. >

Low frequency electromagnetic field reduction techniques for the On-Line Electric Vehicle (OLEV)

In this paper, we introduce the On-line Electric Vehicle (OLEV) system and its non-contact power transfer mechanism and propose some techniques for the reduction of electromagnetic fields (EMFs) from the power line and the vehicle itself. By applying a metallic plate shield, horizontal/vertical shield, and connecting wire for loop cancellation, the low frequency EMFs have been significantly reduced. Simulation and measurement results for application to vehicles currently in service are also given.