• Journal of Power Electronics
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• v.19 no.1
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• pp.278-287
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• 2019

In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter is comprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source, and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presented to investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoretical analysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method is proposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-based totem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.

• International Journal of Highway Engineering
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• v.14 no.4
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• pp.125-131
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• 2012

PURPOSES : Road lighting facilities increase the visibility of road at night in order to improve traffic driver safety and comfort. Generally speaking, current pole lighting has a tendency to create problems of glare and flicker. The phenomenon of glare gives discomfort due to increase of scattered light, when high luminance is in driver's field of view. The phenomenon of flicker occurs due to the driver passing through discontinuous pockets of pole lighting areas. These phenomenon increase eye strain and decrease driver safety. METHODS : Low height line lighting that distributes light lower than driver's eye level has been developed and evaluated to reduce the problems linked to current pole lighting. A test was undertaken with 4 conditions(turn on the general pole lighting, turn off alternate pole lighting, turn on the line lighting and line lighting with 50% dimming). A driver written survey was conducted in order to gain driver feedback. RESULTS : Pupil size and brow frequency compared with degree in pole lighting are reduced. CONCLUSIONS : Low height line lighting environment makes drivers more comfortable than pole lighting environment and is positive lighting method in the energy saving and landscape aspect.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.982-983
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• 2006

This paper deals with an analysis and design of the state feedback current controller's gain in the three-phase current control systems. First, this paper derives the transfer function of the closed loop current control system and also compares the state feedback current controller with the conventional proportional integral controller. A new pole placement method by using the pole/zero cancellation method is proposed to give a simple and concrete concept with respect to the pole selection. Experimental results on the permanent magnet synchronous motor show that the proposed method is very useful to design the gain of the state feedback current controller.

• Journal of Power Electronics
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• v.9 no.6
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• pp.845-853
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• 2009

This paper presents a novel hybrid pole BLSRM (Bearingless Switched Reluctance Motor) and its radial force control scheme. The proposed hybrid pole BLSRM has separated radial force poles and rotating torque poles. According to the FEM analysis, the proposed BLSRM has an excellent linear characteristic of radial force and controllability that is independent from the torque current. The radial force can be produced by the radial force winding which is wound at the separated radial force poles. The rotating torque is produced by the excitation current of the torque windings which are wound at the torque pole. The proposed radial force control scheme is independent of the phase torque winding current. A simple PID controller and look-up table are used to maintain a constant rotor air-gap. The proposed BLSRM and its radial force control scheme are verified by FEM analysis and experimental tests.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.37-44
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• 2003

This paper proposes on-line based a deterioration diagnosis pole transformers using various sensors such as thermistor, current transformer and potential transformer. We measured load current and temperature to diagnose pole transformer using R/F( radio frequency ) wireless data communication module. We represent the graphs of their feature. The result of this paper shows that the proposed device car be used as deterioration diagnosis device of pole transformers.

• 전기의세계
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• v.24 no.1
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• pp.55-62
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• 1975

A single-phase induction motor with it's stator winding splitted into two series windings, of which the terminals of one winding is switched pulsationally by a thyristor type ON-OFF device so that the motor may operate as a pulsational shaded-pole motor, can modulate current waveforms of it's two series windings. In view of current waveform modulation method, a single-phase single-winding motor operates as a two-phase induction motor with asymmetrical axis windings where the starting torque can be obtained effectively without an auxiliary capacitor attached and it's running speed controlled by shifting phase between current waveforms differently. Equivalent circuit for analysis is modified from a double revolving field equivalent circuit of a single-phase induction motor with asymmetrical windings whose angle is 45.deg.C elet. degrees. Analysis and test results show that ON-OFF action of the pulsational shaded-pole winding has the same effect of a series capacitor, and then at heavy loads this motor operates with a small amonut of the input current than that having the fixed shaded-pole winding.

• Journal of Power Electronics
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• v.13 no.3
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• pp.447-457
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• 2013

For grid-connected LCL-filtered inverters, resonance yields instability and low bandwidth. As a result, careful designs are required. This paper presents a systematic current control structure, where pole assignment consisting of one or more feedbacks is the inner loop, and the outer loop is the direct grid current control. Several other issues are discussed, such as the inner-loop feedback choices, pole-assignment algorithms, robustness and harmonic rejection. Generally, this kind of strategy has three different types according to the inner-loop feedback choices. Among them, a novel pole-assignment algorithm has been proposed, where the inner control maintains four freely-assigned poles which are just two pairs of conjugated poles located at the fundamental and resonance frequencies separately. It has been found that with the different types, the steady-state and dynamic performances are quite different. Finally, simulations and experiments have been provided to verify the control and design of the proposed methods.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.480-484
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• 2000

The pole placement technique for control design of the current mode controlled DC-DC switchmode power converter is proposed. It is compared with conventional transfer function analysis. Using the pole placement technique control design automation algorithm, by computer-based tool is presented. Control design example with large signal simulation is shown.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.3
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• pp.331-338
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• 2014

When large penetration of the distributed generators (DGs) such as photovoltaic (PV) systems is growing up in grid system, it is important to quickly prevent islanding caused by power system fault to ensure electrical safety. We propose a novel active method for islanding prevention by harmonic injection synchronized with the exciting current harmonics of the pole transformer to avoid mutual interference between active signals. We confirm the validity of the proposed method by performing the basic tests of islanding by using a current source superimposed the harmonic active signal. Further, we carry out the simulation using PSCAD/EMTDC, and verify the fast islanding detection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.685-695
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• 1997

In this paper, a new CMOS continuous-time fully-differential current-mode integrator is proposed as a basic building block of the low-voltage high frequency current-mode active filter. The proposed integrator is composed of the CMOS complementary circuit which can extend transconductance of an integrator. Therefore, the unity gain frequency which is determined by a small-signal transconductance and a MOSFET gate capacitance can be expanded by the complementary transconductance of the proposed integrator. And also the magnitude of pole and zero are increased. The unity gain frequency of the proposed integrator is increased about two times larger than that of the conventional continuous-time fully-differential integrator with NMOS-gm. These results are verified by the small signal analysis and the SPICE simulation. As an application circuit of the proposed fully-differential current-mode integrator, the three-pole Chebyshev lowpass filter is designed using 0.8.$\mu$m CMOS processing parameters. SPICE simulation predicts a 3-dB bandwidth of 148MHz and power dissipation of 4.3mW/pole for the three-pole filter with 3-V power supply.