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AC power

About: AC power is a research topic. Over the lifetime, 80943 publications have been published within this topic receiving 880865 citations.


Papers
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Journal ArticleDOI
TL;DR: The authors demonstrated the effectiveness of the proposed control scheme by using computer simulation and experiments to eliminate the DC link voltage ripple and the DC component of the reactive power.
Abstract: Voltage unbalance in a three-phase system causes performance deterioration of PWM power converters by producing 120 Hz voltage ripples in the DC link and by increasing the reactive power. To eliminate the DC link voltage ripple and the DC component of the reactive power, both positive- and negative-sequence currents should be controlled simultaneously, according to the paper by Rioual et al (1996). The authors used two synchronous reference frames: a positive-sequence current regulated by a proportional integral (PI) controller in a positive synchronous reference frame (SRF); and a negative-sequence current regulated by a PI controller in a negative SRF. In the positive SRF, which rotates counterclockwise, the positive sequence appears as DC, while the negative sequence appears as 120 Hz. In contrast, in the negative SRF, which rotates clockwise, the negative sequence appears as DC, while the positive sequence appears as 120 Hz. By deleting 120 Hz components using a notch filter in each SRF, one can measure positive- and negative-sequence currents separately, and use them for constructing two feedback controllers. Since the negative-sequence current is also controlled in its own SRF by a DC command, this approach yields better performance without increasing the control gain. Note that, since the controller is implemented by a software routine in the digital signal professor chip, using two SRFs does not require additional hardware. The authors demonstrated the effectiveness of the proposed control scheme by using computer simulation and experiments.

930 citations

Journal ArticleDOI
TL;DR: In this paper, a dual-phase-shift (DPS) control strategy for a dual active-bridge isolated bidirectional DC-DC converter is proposed, which consists of a phase shift between the primary and secondary voltages of the isolation transformer, and a phase shifting between the gate signals of the diagonal switches of each H-bridge.
Abstract: This paper proposes a novel dual-phase-shift (DPS) control strategy for a dual-active-bridge isolated bidirectional DC-DC converter. The proposed DPS control consists of a phase shift between the primary and secondary voltages of the isolation transformer, and a phase shift between the gate signals of the diagonal switches of each H-bridge. Simulation on a 600-V/5-kW prototype shows that the DPS control has excellent dynamic and static performance compared to the traditional phase-shift control (single phase shift). In this paper, the concept of ldquoreactive powerrdquo is defined, and the corresponding equations are derived for isolated bidirectional DC-DC converters. It is shown that the reactive power in traditional phase-shift control is inherent, and is the main factor contributing to large peak current and large system loss. The DPS control can eliminate reactive power in isolated bidirectional DC-DC converters. In addition, the DPS control can decrease the peak inrush current and steady-state current, improve system efficiency, increase system power capability (by 33%), and minimize the output capacitance as compared to the traditional phase-shift control. The soft-switching range and the influence of short-time-scale factors, such as deadband and system-level safe operation area, are also discussed in detail. Under certain operation conditions, deadband compensation can be implemented easily in the DPS control without a current sensor.

912 citations

Journal ArticleDOI
TL;DR: In this article, a solution is described that makes it possible for wind turbines using doubly-fed induction generators to stay connected to the grid during grid faults by limiting the high current in the rotor in order to protect the converter and to provide a bypass for this current via a set of resistors that are connected to rotor windings.
Abstract: In this paper, a solution is described that makes it possible for wind turbines using doubly-fed induction generators to stay connected to the grid during grid faults. The key of the solution is to limit the high current in the rotor in order to protect the converter and to provide a bypass for this current via a set of resistors that are connected to the rotor windings. With these resistors, it is possible to ride through grid faults without disconnecting the turbine from the grid. Because the generator and converter stay connected, the synchronism of operation remains established during and after the fault and normal operation can be continued immediately after the fault has been cleared. An additional feature is that reactive power can be supplied to the grid during long dips in order to facilitate voltage restoration. A control strategy has been developed that takes care of the transition back to normal operation. Without special control action, large transients would occur.

879 citations

Book
01 May 1986
TL;DR: An integrated treatment of technological advances in power electronics with a focus on power semiconductor devices, ac machines, phase-controlled converters and cycloconverters, voltage-fed inverter drives, current-fed inverted drives, slip powercontrolled drives, control of induction and synchronous machines, and microcomputer control.
Abstract: An integrated treatment of technological advances in power electronics Add this article to private library Remove from private library Submit corrections to this record View record in the new ADS and ac drives is presented. The topics include: power semiconductor devices, ac machines, phase-controlled converters and cycloconverters, voltage-fed inverter drives, current-fed inverter drives, slip powercontrolled drives, control of induction and synchronous machines, and microcomputer control. Both practical and theoretical aspects of the technology are addressed, and numerical examples are given. Bibtex entry for this abstract Preferred format for this abstract

850 citations

Proceedings ArticleDOI
06 Oct 1996
TL;DR: In this paper, the authors proposed a novel power control strategy for a PWM converter with no power-source voltage sensors, which has two main features to improve a total power factor and efficiency.
Abstract: This paper proposes a novel control strategy of a pulsewidth modulation (PWM) converter with no power-source voltage sensors. The strategy has two main features to improve a total power factor and efficiency, taking harmonic components into account without detecting the voltage waveforms. One feature is a direct instantaneous power control technique for the converter, which has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter. The other feature is an estimation technique of the power-source voltages, which can be performed by calculating the active and reactive power for each switching state of the converter from the line currents. A digital-signal-processor-based experimental system was developed, and experimental tests were conducted to examine the controllability. As a result, it was confirmed that the total power factor and efficiency were more than 97% and 93% over the load power range from 200 to 1400 W, respectively. These results have proven the excellent performance of the proposed system.

847 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023894
20222,129
20212,993
20204,364
20195,192
20185,526