Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in two-wire (single phase), three-wire (three phase without neutral), and four-wire (three phase with neutral) AC power networks with nonlinear loads. This paper presents a comprehensive review of active filter (AF) configurations, control strategies, selection of components, other related economic and technical considerations, and their selection for specific applications. It is aimed at providing a broad perspective on the status of AF technology to researchers and application engineers dealing with power quality issues. A list of more than 200 research publications on the subject is also appended for a quick reference.

A review of active filters for power quality improvement

This paper comprehensively analyzes the relationship between space-vector modulation and three-phase carrier-based pulse width modulation (PWM). The relationships involved, such as the relationship between modulation signals (including zero-sequence component and fundamental components) and space vectors, the relationship between the modulation signals and the space-vector sectors, the relationship between the switching pattern of space-vector modulation and the type of carrier, and the relationship between the distribution of zero vectors and different zero-sequence signal are systematically established. All the relationships provide a bidirectional bridge for the transformation between carrier-based PWM modulators and space-vector modulation modulators. It is shown that all the drawn conclusions are independent of the load type. Furthermore, the implementations of both space-vector modulation and carrier-based PWM in a closed-loop feedback converter are discussed.

https://u.dianyuan.com/bbs/u/26/1109124433.pdf

Relationship between space-vector modulation and three-phase carrier-based PWM: a comprehensive analysis [three-phase inverters]

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.

Dual current control scheme for PWM converter under unbalanced input voltage conditions

With the rapid developments in very large-scale integration (VLSI) technology, design and computer-aided design (CAD) techniques, at both the chip and package level, the operating frequencies are fast reaching the vicinity of gigahertz and switching times are getting to the subnanosecond levels. The ever increasing quest for high-speed applications is placing higher demands on interconnect performance and highlighted the previously negligible effects of interconnects such as ringing, signal delay, distortion, reflections, and crosstalk. In this review paper various high-speed interconnect effects are briefly discussed. In addition, recent advances in transmission line macromodeling techniques are presented. Also, simulation of high-speed interconnects using model-reduction-based algorithms is discussed in detail.

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Simulation of high-speed interconnects

This paper presents first an overview of the well-known voltage and current dc-link converter topologies used to implement a three-phase PWM ac-ac converter system. Starting from the voltage source inverter and the current source rectifier, the basics of space vector modulation are summarized. Based on that, the topology of the indirect matrix converter (IMC) and its modulation are gradually developed from a voltage dc-link back-to-back converter by omitting the dc-link capacitor. In the next step, the topology of the conventional (direct) matrix converter (CMC) is introduced, and the relationship between the IMC and the CMCs is discussed in a figurative manner by investigating the switching states. Subsequently, three-phase ac-ac buck-type chopper circuits are considered as a special case of matrix converters (MCs), and a summary of extended MC topologies is provided, including three-level and hybrid MCs. Therewith, a common knowledge basis of the individual converter topologies is established.

Review of Three-Phase PWM AC–AC Converter Topologies

The authors propose an improved version of the known pulse width modulation (PWM) controller topologies that can become a practical alternative to line-commutated AC controllers. The improvements include the use of typical unilateral switches, typical gating patterns, and reliability enhancing by-pass capacitors. The authors also present the analysis and design of the proposed converter topology, with key theoretical results verified experimentally on a 10 kVA breadboard. >

A practical PWM AC controller topology

In this paper, an improved version of PWM AC line conditioners is proposed. As compared to previously reported structures, it uses fewer standard switch modules. This, in combination with less stringent gating requirements, improves the overall operating reliability of the system. In addition, it retains the same advantages of a regular force-commutated AC line conditioner, including sinusoidal input-output waveforms, fast dynamic response, and small input-output filters. The operating principle of the proposed structure is discussed, and the voltage feedback loop design is analyzed. Results from a 25 kVA experimental setup are provided for verification. >

Design and implementation of a 25-kVA three-phase PWM AC line conditioner

The analysis and design of a direct six-switch three-phase PWM rectifier, capable of correcting input unbalance, is presented. Based on the input source positive and negative sequence components, an unbalanced transfer matrix in terms of input phase voltages is derived. An online method is used to implement the transfer matrix function and generate the switch gating signals. As compared to other unbalance correction methods, the proposed approach is very simple to implement. It uses only a few discrete analog and digital components. The algorithm of the proposed approach is described in this paper, and results are verified from a 1 kVA breadboard set-up. >

A three-phase regulated PWM rectifier with on-line feedforward input unbalance correction

A pulse-width-modulation (PWM) scheme that uses the converter switching frequency to minimize unwanted load current harmonics is described. This results in the reduction of the number of switch communications per cycle. The method is suitable for high-performance variable-speed AC-motor drives that require high-output switching frequencies for near-silent operation. It is also applicable, without change, to voltage or current-source inverters and to two and four-quadrant three-phase PWM rectifiers. Key predicted results have been verified experimentally on a 5 kVA inverter breadboard. >

A refined PWM scheme for voltage and current source converters

A model reference adaptive (MRA) pulsewidth-modulated (PWM) technique for invertor switching applications is presented and analyzed. With this technique, the near optimal inverter gating signals are determined through a closed-loop process which compares a reference signal to a feedback signal derived from a built-in reference model of the load. In addition to its simplicity of implementation, the proposed PWM technique has the advantages of inherent controlled constant volts-per-Hertz (V/f) ratio operation and jitter-free operation with free-running carrier. Such features are of importance in variable-speed AC-drive applications where V/f control increases the control-circuit complexity and where carrier frequency jumps cause harmful torque/speed transients. >

D. Vincenti

Papers

A practical PWM AC controller topology

Design and implementation of a 25-kVA three-phase PWM AC line conditioner

A three-phase regulated PWM rectifier with on-line feedforward input unbalance correction

A refined PWM scheme for voltage and current source converters

A model reference adaptive PWM technique