Current Source Load Research Articles

Analysis and Control of a Single-Phase-Inverter–Zigzag-Transformer Hybrid Neutral-Current Suppressor in Three-Phase Four-Wire Systems

This paper presents analysis and control of a hybrid filter that can suppress neutral harmonic currents in three-phase four-wire systems not only with harmonic voltage-source loads but also with harmonic current-source loads. The filter voltampere rating is significantly reduced compared to the conventional neutral-current-suppressing methods. The rectifier part of the neutral harmonic suppressor has been removed by controlling the dc capacitor voltage. The experimental results on a 50-kVA prototype validate the proposed control approach.

A Fully Differential VCO Cell with Active Inductors for Gbps Serial Links

This paper investigates the distinct characteristics of cross-coupled fully differential ring VCO delay cells with resistor, current-source, and active inductor loads. In addition, it proposes a ne...

400‐kV‐network harmonic impedance evaluation from harmonic distortion measurements at the RFX site

AbstractThe lack of knowledge of the harmonic frequency behaviour of the extra‐high‐voltage (EHV) transmission network prevents the possibility to choose, at the design stage, an appropriate system for harmonic mitigation for current harmonic source loads directly fed by the transmission network, as well as arc furnaces and facilities for thermonuclear fusion researches. The paper describes the methodology employed to determine the harmonic network impedance from current and voltage measurement seen at the Camin‐Padova node of the Italian transmission network, in which are injected the current harmonics produced by the reversed field pinch experiment (RFX) fusion facility; in particular, a simple method for precise measurement of voltage harmonics is presented in detail.

Compensation Characteristics of Shunt Active and Series Active Power Filters.

Active power filters have been used in practice to suppress the harmonic interference in power systems. To compensate for harmonic currents of loads active power filters are usually connected to power systems in parallel with the loads. These filters which are called shunt active filters here are very effective to loads that can be considered as current sources, such a thyristor rectifiers with large DC reactances. Many papers have covered the shunt active filters applied to these currentsource loads. No paper, however, has discussed characteristics of the shunt active filters when they are applied to voltage-source loads.On the other hand, since more and more diode rectifiers with capacitive DC filters are used recently, harmonics generated by which become an issue.The diode rectifier with capacitive DC filters behaves like a voltage source rather than a current source. When a shunt active filter is applied to such a diode rectifier, the current injected from the shunt active filter may flow into the diode rectifier. As a result, harmonics of the source current cannot be reduced effectively, and harmonic current flowing into the diode rectifier increases largely.This paper reveals the above-mentioned problem of shunt active filters analytically and experimentally. Then a series active filter is proposed to suppress harmonic current of the diode rectifiers. The features, operating conditions, and considerations of shunt active filters and series active filters are described analytically and demonstrated experimentally. Taking a diode rectifier with capacitive DC filter as a typical voltage-source load, compensation characteristics of shunt active filters and series active filters are discussed by experiment and simulation. The validity of the series active filters is illustrated experimentally.

Self-electro-optic device based on a superlattice asymmetric Fabry–Perot modulator with an on/off ratio ≳100:1

A self-electro-optic effect device based on a Fabry–Perot reflection modulator has been demonstrated for the first time. This modulator is a normally-off high-contrast asymmetric Fabry–Perot modulator using Wannier–Stark localization in a superlattice. Optical bistability has been achieved with a record-high on/off ratio of 130:1 at the operating wavelength of 7620 Å. The modulator with an appropriate reverse-bias voltage supply was connected in series to a silicon photodiode which when illuminated with an appropriate light source acted as a current source load for the modulator.