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SUMMARY This paper proposes a highly efficient drive method for an open-winding induction machine with a single constant voltage source and a single capacitor. By focusing on the phase voltage of the open-winding machine, which is determined by the phase difference and the dc voltage of each power converter, it is possible to control the peak value of the phase voltage by controlling the voltage of the capacitor. Thus, a reduction in the iron loss due to harmonic voltage in the open-winding machine is expected. In the proposed method, the voltage of the capacitor is controlled by the difference between the two reference voltages of the power converter, which depends on the machine power factor and the phase difference of the power converter connected to both ends of the winding. Based on experimental results, the converter loss and the machine loss can be reduced by controlling the voltage of the capacitor in accordance with the machine speed using the proposed method.

SUMMARY The effect of the arc voltage on various factors of design and control was investigated for high currents in order to develop design guidelines for circuit breakers. In this study, the dependence on such factors, namely, the current, arc length, electrode surface area, and internal pressure of the arc voltage, was evaluated quantitatively. As a result of the evaluations, it was estimated that the arc voltage near the electrode surface rises linearly with the arc current and the power −0.8 of the surface area, and that the voltage in the arc column rises as the 0.3 power of the pressure increase. We confirmed the validity of the estimated voltage characteristics by comparison with the generated voltage in an actual arc-extinction chamber. The characteristics of the estimated voltage can provide effective guidelines for the design of arc extinguishing chambers. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 34–42, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22487

This research work proposes to detect arc conditions of electric arc furnaces (EAFs) based upon digital signal processing of the line to ground three-phase voltage measurements at the secondary side of the furnace transformer. It uses the voltage difference between a virtual-neutral point of the symmetrical power source and the furnace shell ground voltage. For harmonic analysis this voltage is processed using Fourier transform. The obtained information is found to be useful to detect arc operational conditions like arc stability, arc balance, and arc slag coverage. With the here in proposed arc indicators, the power control of the EAF can be performed using the concept of a dynamic power profile to set the operational transformer tap and current set points of the EAF control systems.

We propose a novel method to drive ultra-large size and high resolution LCD TV with a single-bank data driver scheme without severe image degradation. We could achieve a maximum luminance and uniformity to be 98cd/m2 and 86%, respectively when gray 128 is displayed. This confirms excellent performance because the conventional dual-bank driver scheme achieves the counterparts to be 90cd/m2 and 93%.

The internal voltage gradient and behavior of column on long-gap DC free arcs were analyzed quantitatively. In the analysis, an image processing technique developed by us was applied to the images shot from two orthogonal views by two high-speed video cameras to estimate the three-dimensional arc column paths. Objective free arcs were ignited between the rod electrodes with the current in the range of 100 to 2000A and the gap in the range of 1.6 to 3.2 m. In addition, some of the objective free arcs were placed in the external magnetic field brought about by a large coil. As a result, macroscopic changes with time in terms of the arc voltage gradient along the column path, the ratio of the arc column length to the gap length, and the distance from the center axis between the electrodes to the farthest point were derived. All average characteristics were shown as the experimental equations. In addition, the effect of the external magnetic field on the macroscopic velocity of the expansion was studied. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(3): 8–16, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10198

A test set-up is presented which is able to measure the arc voltage of vacuum interrupters after breakdown with currents in the lower kHz-range. Arc voltage measurements from this set-up are presented. The obtained dynamic voltage/current characteristics are discussed and compared to the known voltage current characteristic of a power frequency arc in vacuum. A simple vacuum arc model is presented describing the voltage current characteristic. The model is applied to assess the energy dissipation in the arc.

This paper considers breaking of the dc circuit by electrical contact and describes a method for measuring the voltage and current waveforms of the breaking arc and surge, as well as a method for deriving the arc equivalent circuit in the latter period of the breaking arc. The small inductance of the whole simulating circuit as well as the equivalent capacitance of the electrical contacts are determined so that the observed voltage waveform induced in the text circuit during the surge (i.e., the induced voltage waveform after chopping) and the voltage value in the resistor calculated in the simulating circuit agree. Next, the equivalent arc resistance, coherence, and the phase angle are calculated from the voltage and current waveforms of the breaking arc, which contain the high-frequency components. Using the equivalent capacitance, equivalent arc resistance and phase angle, the arc equivalent circuit is estimated that can simulate the measured arc voltage and current waveforms. It is seen as a result that the arc equivalent circuit in the latter discharge period of the breaking arc can be represented as a series-parallel circuit where resistor ra1 is connected to the parallel circuit (ra2/Ca) of resistor ra2 and the equivalent capacitance Ca. When, for example, the Ag electrical contact on a relay breaks the circuit of dc 36-V and a noninductive resistor 3 ω, the arc equivalent circuit in the 105 ∼ 106 band in the latter period of the breaking arc is constructed by ra1 = 65 ω, ra2 = −68 ω, and Ca = 200 pF.

As a method of compensating for the voltage drop on the dc side of ferroresonant dc stabilized power supplies, a magnetic-only controlled power supply was developed. When a dc magnetic field is applied in the direction of diameter of a saturable ring core, using the saturation flux density, that is, resonant voltage change, by dc load current feedback to an electromagnet positioned in the diametric direction, the resonant voltage is altered and output voltage stabilization is achieved. By increasing the operation frequency of the power supply, miniaturization is achieved and simultaneously, as a feedback control method, is expressed in a block diagram. An investigation was made on the power supply design method and the response to various disturbances. As a result, design criteria were established to make the steady-state output voltage error zero. The transient response simulation was verified to explain well the experimental result.

Scope of Deliverables: This section covers early applications of electricity to pasteurize fluids. The use of arc discharge for liquid foods is unsuitable largely because electrolysis and the formation of highly reactive chemicals occur during the discharge. More recent designs show some promise for this technology, although this should be confirmed by independent researchers.

The PMOLED (Passive Matrix Organic Light Emitting Diode) panel size is limited due to the various reasons; increase of power consumption, degradation of display quality and so on. Suppressing the increment of pre-charge power consumption according to the increment of panel size is one of the main power issues. The PMOLED driver IC with proposed alternative pre-charge algorithm for saving pre-charge power is presented in this paper. This driver IC is applied to the QCIF+(220RGB×176) panel. The pre-charge power consumption of driver IC with proposed alternative pre-charge method can be reduced by 50∼70% of the normal method without displays quality degradation.

We have developed an integrated poly-Si TFT current data driver with a data-line pre-charge function for active-matrix organic light-emitting diode (AMOLED) displays. The current data driver is capable of outputting highly accurate (±0.8%) current determined by 6-bit digital input data. A novel current-programming approach employing a data-line pre-charge function helps achieve accurate current programming at low brightness. A 1.9-in. 120 x 136-pixel AMOLED display using these circuits was demonstrated.