Three-phase

About: Three-phase is a research topic. Over the lifetime, 16801 publications have been published within this topic receiving 159477 citations.

Integrated AC/DC and DC/DC converter

Abstract: In an illustrative embodiment, a power converter for starting an AC machine comprises at least one transformer for stepping-up AC source voltages, at least one rectifier for rectifying output voltages from the at least one transformer, a three phase inverter for inverting rectified voltages from the at least one rectifier for providing three phase voltages for starting the AC machine, and a DC to AC converter for converting DC source voltage to AC inverted voltages. The three phase voltages for starting the AC machine are derived from one of the AC and DC source voltages through the at least one transformer and the at least one rectifier.

Minimum inverter capacity design for LC-hybrid active power filters in three-phase four-wire distribution systems

Abstract: This study presents a minimum inverter capacity design for three-phase four-wire centre-split inductor-capacitor (LC) coupling hybrid active power filters (LC-HAPFs). Based on its equivalent circuit models in d - q -0 coordinate, the coupling part filtering characteristics of the LC-HAPF without or with neutral inductor can be more clearly illustrated and easily understood, compared with the past analysis based on the generic filter structure. According to the current quality data, the minimum dc-link voltage expressions for the LC-HAPF without and with neutral inductor are deduced and compared. Conventionally, the coupling LC is usually tuned at a higher fifth- or seventh-order harmonic frequency to reduce its cost and size compared with third-order case. When triplen harmonic currents exist significantly, the LC-HAPF with a small tuned neutral inductor can further reduce its minimum dc-link voltage requirement. Thus, the initial cost, switching loss and switching noise of the LC-HAPF can be lowered. Representative simulation and experimental results of the three-phase four-wire LC-HAPF with neutral inductor are presented to verify the filtering characteristics analysis and minimum dc-link voltage expressions, to show the effectiveness of reducing its inverter capacity, switching loss and switching noise in current quality compensation compared with the conventional LC-HAPF.

A novel, robust, harmonic injection method for single-switch, three-phase, discontinuous-conduction-mode boost rectifiers

Abstract: This paper describes a new robust low-cost harmonic-injection method for single-switch three-phase discontinuous-conduction-mode (DCM) boost rectifiers. In the proposed method, a periodic voltage is injected in the control circuit to vary the duty cycle of the rectifier switch within a line cycle so that the fifth-order harmonic of the input current is reduced to meet the IEC555-2 requirement. Since the injected voltage signal, which is proportional to the inverted AC component of the rectified three-phase line-to-line input voltages, is employed, the injected duty-cycle variations are naturally synchronized with the three-phase line-to-neutral input voltages. In addition, the injected harmonic signal naturally contains desirable higher order harmonics, such as sixth, twelfth, eighteenth, etc., which are more effective in improving total harmonic distortions (THDs) than harmonic-injection methods based on the sixth-order harmonic only.

Proposal of Three-Phase High-Frequency Transformer Isolation UPS Topologies for Distributed Generation Applications

Abstract: A family of double-conversion three-phase uninterruptible power systems with power factor correction and high-frequency transformer (HFT) isolation topologies are presented in this paper. This might be a suitable alternative compared to large conventional uninterruptible power systems (UPSs) that are based upon bulky transformers that operate at the grid frequency. This system is commonly used to supply critical loads, but nowadays, due to the increasing interest in renewable energy integration and distributed generation (DG), it can also be a suitable solution for energy storage in microgrids or renewable-power-conditioning interface applications. The three-phase HFT UPS used for further analysis is composed of single-phase chopper modules, one three-phase boost module, and one three-phase inverter. The relevant features are soft commutation of the controlled switches in the chopper stage, simple control strategy that can be implemented with well-known integrated circuits, and the use of a few batteries in series due to the same reference of the step-up stages. The principle of operation of the chosen system for experimental validation, the implemented control strategy, and the experimental results obtained for a 15-kVA prototype are presented.

Digitized Feedforward Compensation Method for High-Power-Density Three-Phase Vienna PFC Converter

Abstract: This paper presents a front-end three-phase ac/dc power factor correction rectifier, which is based on the three-level bidirectional-switch Vienna topology. On one hand, the rectifier is designed to operate in continuous-conduction mode (CCM) at full power. However, at reduced load, it operates in discontinuous-conduction mode (DCM). On the other hand, with reduced input inductance, the DCM mode occurs even when the rectifier operates at full power. In this paper, the digitized feedfoward compensation method is proposed for the rectifier to reduce the impact of the switch between DCM and CCM. The theoretical analysis of the proposed method is deduced; furthermore, the control design strategy is given. The experimental results are obtained by using a digitally controlled Vienna rectifier, which validated the proposed compensation method.