Output Current Of Converter Research Articles

The effect of Schottky barrier lowering and nonplanar emitter geometry on the performance of a thermionic energy converter

An extension of the classical model of thermionic emission was developed to include the effects of nonplanar emitter surfaces and Schottky barrier lowering (SBL) on the output of a thermionic energy converter (TEC). Nonplanar emitter geometries along with Schottky barrier lowering may be useful in increasing both the maximum output power and output current of a thermionic energy converter. The finite element method was used to calculate the enhanced normal electric field at the surface of an emitter coated with an ultra-nanocrystalline diamond (UNCD) film and patterned with field enhancing tips. The result was used to determine the local enhanced output current and power. For the geometries considered the increased surface area of the emitter plays a significant role in increasing the output power and output current. Moreover, a calculation of the single electron time of flight shows that electrons traveling through a field enhanced region of the interelectrode space might spend half as long in transit, thus helping to mitigate the negative space charge effect that degrades the performance of vacuum TECs.

Uninterruptible power supply multiloop control employing digital predictive voltage and current regulators

A digital control technique for the inverter stage of uninterruptible power supplies (UPSs) is described, which is based on voltage and current predictive regulators. Its aim is to achieve a deadbeat dynamic response for the controlled variables (output voltage and inverter current). The controller maintains the advantageous conventional multiloop structure and is capable of guaranteeing a high-quality dynamic performance. Moreover, its design is extremely simple and requires only a reasonably accurate knowledge of the output filter parameters. Finally, the only sensed variables are the output voltage and the converter output current. The validity of the proposed strategy is demonstrated by means of simulation and experimental results referring to a single-phase UPS laboratory prototype (1 kVA).

On the current balance of phase-controlled thyristor converter having interphase reactors.

A parallel connected thyristor converter with an interphase reactor has been used widely as a low voltage high current DC power supply because of high efficiency, compared with a series one. It seems to be the most suitable for superconducting magnetic energy storage systems in particular. If the parallel converter consisting of two thyristor converters is operated under different firing angles in the two due to imperfect adjustment in the control circuit or something like that, unbalance may occur in the output DC current of each converter.The purpose of this paper is to discuss the current unbalance of a parallel thyristor converter in detail. The main points are summarized as follows:(1) It is clarified theoretically that the unbalance of DC output current may occur even when the difference of firing angles is less than 1°.(2) It is verified experimentally that the proposed simple current feedback makes it possible to balance the DC output current of the parallel thyristor converter.(3) An interphase reactor without gap is able to take the place of a conventional interphase reactor with gap which is used widely. Compared with the conventional one, the volume of the interphase reactor without gap is much small.

不安定波動のある磁界中熱電子発電器の出力電流

不安定波動のある磁界中熱電子発電器の出力電流

A Self Commutated Power Converter for Stabilizing Torsional Interactions

A recently proposed method of counteracting torsional interactions referred to as transmission current feedback involves the measurement of the transmission system currents from which the subsynchronous components that produce torsional interactions are extracted. Once extracted, these are suitably amplified by a power converter and injected into the generator bus of the affected steam turbine so as to cancel the original subsynchronous components which would otherwise produce torsional interactions. In this paper, a power converter capable of supplying the required subsynchronous currents is described. An analytic model relating the converter output currents to its controlling variables is derived and a suitable control strategy is formulated. A detailed hybrid computer simulation of the converter is used to verify the accuracy of the analytic representation of the converter and the effectiveness of the control strategy.