Comparative Study of Pulse Width Modulated and Phase Controlled Rectifiers (original) (raw)
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IJERT-Comparative Study of Pulse Width Modulated and Phase Controlled Rectifiers
International Journal of Engineering Research and Technology (IJERT), 2016
https://www.ijert.org/comparative-study-of-pulse-width-modulated-and-phase-controlled-rectifiers https://www.ijert.org/research/comparative-study-of-pulse-width-modulated-and-phase-controlled-rectifiers-IJERTV4IS120537.pdf Fixed DC voltage is one of the very basic requirements of the electronics' circuits in modern systems. Thus, single phase diode or thyristor rectifiers are commonly used in many industrial applications where we require a high-power DC supply or an intermediate DC link of AC/AC converters. The benefits include simple structure, high safety and most importantly, low cost. However, it is reasonable to assume that a price is to be paid for these benefits. The major drawback is the power system harmonics that these bridge rectifiers introduce within a system. The economic advantage that these systems enjoy can be nullified overnight if stricter harmonic standards are implemented. With this in mind, there is an increased interest in active filters and schemes like PWM that can counter these. The less prominent (but important from the consumers' point of view) issues include low power factor, voltage distortion, heating of transformer cores etc. A single standard scheme that can work for all applications is an ideal yet impractical solution. Thus, different schemes that have been introduced need to be compared so that it is easier to choose whichever fits best with the task at hand.
DESIGN AND IMPLEMENTATION OF A PULSE WIDTH MODULATED RECTIFIER FOR INDUSTRIAL APPLICATIONS
Three phase pulse width modulated voltage source rectifiers are widely used in uninterruptible power supplyand motor drive applications due to their low input current THD, adjustable input power factor,and bi-directional power transfer characteristics.In this paper utilization of this type of rectifier at the front end unit of an industrial type uninterrupted power supply is discussed. DC bus voltage is controlled through two high gain PI controllers. Sinusoidal Pulse Width Adjustable Triangle Wave Comparison for switching (SPWM) was selected as the control method. Unity power factor has been attained at the input along with very low THD values.
MITIGATION OF HARMONICS USING THYRISTOR BASED 12 PULSE VOLTAGE SOURCE PWM RECTIFIER
IJRET, 2012
Three-phase thyristor rectifiers have been used in industries for obtaining a variable dc voltage, but they have a problem of including large lower-order harmonics in the input currents. For high-power applications, a 12-pulse configuration is useful for reducing the harmonics, but it still includes the (12m ± 1) th (m: integer) harmonics. In order to further reduce the harmonics, this paper proposes to supply a ramp wave voltage at the input of a 12-pulse phase-controlled rectifier. Theoretical investigation to reduce harmonics is presented, and a strategy to control the regulated voltage and unity power factor at input side based on 12 pulse modulation technique. This paper discuss the impact of using 3-phase and 12-pulse rectifier circuit commonly found in unity power factor at input ac mains and regulate output voltage. The 12-pulse topology is known to be more expensive, but produce the least input current harmonics. However, the latter statement is completely true under balanced line conditions. In practice, the lines are inherently unbalanced. Hence, the question of whether the 12-pulse rectifier will indeed perform better in terms of the harmonics injected to the line is still under on-going discussions. This presents the modelling and simulation of both rectifier topologies to compare their input current and regulated output voltage harmonics. The rectifiers are modelled using the MATLAB/SIMULINK simulation model and several common cases conditions will be simulated to compare their harmonic levels.
Global Journal of Research In Engineering, 2016
Harmonic distortion is a huge problem for the power systems. But harmonic distortion can be controlled using some unique methods with the utility systems. This paper discusses the impact of using 12- pulse and 24-pulse rectifier circuit. The 24-pulse topology is generally more expensive, but produces the least Input current harmonics. In this paper pulsemultiplication technique is used to mitigate the harmonic distortion from the input line current. Phase-shifting transformers are used to produce 24-pulse from 12- pulse. A comparison between 12-pulse and 24-pulse rectifier also shown in this paper. Operation of the circuits is verified through computer simulations.
Seminar-PWM Regenerative Rectifiers State of the Art
New regulations impose more stringent limits on current harmonics injected by power converters that are achieved with pulsewidth-modulated (PWM) rectifiers. In addition, several applications demand the capability of power regeneration to the power supply. This paper presents the state of the art in the field of regenerative rectifiers with reduced input harmonics and improved power factor. Regenerative rectifiers are able to deliver energy back from the dc side to the ac power supply.
Improvement of Power Quality Using PWM Rectifiers
The paper presents the modeling, simulation and analysis of an AC-DC converter based PWM rectifier. It provides a suitable control algorithm for a pulse width modulation rectifier which reduces ripple from the DC output side as well as shapes the input current properly. The basic objective of a PWM rectifier is to regulate the DC output voltage and also ensure a sinusoidal input current and unity power factor operation. This is implemented by high speed IGBT switches connected in anti parallel mode across the rectifier diodes. The output voltage is controlled by switching these IGBTS and higher order ripples at the output can be easily eliminated with the help of passive filters. Lower order harmonics are eliminated using PWM technique. The control subsystem generates gating pulse to the universal bridge by passing the output voltage through a network consisting of comparator, discrete PI controller and discrete PWM generator. The output of this generator are the gating pulses to be applied to the universal bridge.
Conventional converters have a trouble with the high amount of source current harmonics, poor power factor and more ripples. To overcome the above issues, direct parallel connection of two 2-pulse converter has been proposed. Here, Two MOSFET converter circuits are connected in anti parallel with the common DC load. These MOSFET converters are fed from PWM sources, the PWM pulses are generated from the microcontroller. Configuration consists of two MOSFET converters connected back to back. Converter one is operated during positive half cycle (0-90 deg) and the converter two is sustained during negative half cycle (90-180 deg). This strategy accomplishes and yields the desired output signals without ripples and input signal is same for converting time. This converter helps to reduce the source current harmonics and improve the performance factors compared with conventional circuits. There is no additional circuit required for all operating conditions. This converter modifies naturally to guarantee that base consonant execution over the wide voltage range.
IJERT-Application Of PWM Rectifiertechnology For Harmonic Reduction In Smart Grid
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/application-of-pwm-rectifiertechnology-for-harmonic-reduction-in-smart-grid https://www.ijert.org/research/application-of-pwm-rectifiertechnology-for-harmonic-reduction-in-smart-grid-IJERTV1IS7215.pdf The present focus of every power system is theadoption of renewable energy.But this generated output from renewable energy is difficult to control and may cause frequency and local voltage fluctuations which calls for grid modernization.Smart grid is a systemthat reduces effect of mass adoption of renewable energy. This calls for methods to improve quality of power being transmitted and hence a major concern of harmonic reduction comes to play. The three phase thyristerized rectifiers are used for AC to DC conversion which results in harmonics being produced. This study shows the variation of power factor and output voltage with respect to firing angle for three phase thyristerized rectifier. Calculations are made to predict that the level of disturbance in power factor is considerable and must be mitigated. So are the harmonics produced which needs to be controlled. It's hence a proposed theory that PWM rectifier technology is one way of reducing harmonics in smart grid system.
Power Quality Enhancement and Harmonics Reduction in Non Linear Loads using Vienna Rectifier
This project is designed to improve power quality and to reduce current type harmonics distortion and power factor correction in domestic non linear loads with the help of Vienna rectifier (three phase three level three switch pulse width modulation rectifier). Harmonics distortion in electric distribution system is increasingly growing due to the widespread use of non linear loads. Most modern power supplies are non linear load which contains electronic devices that do not conduct current over the full cycle of the applied voltage and so introduce harmonics in to the power network. Hence improve the power quality and gives unity power factor from supply side. The paper compiles and discusses the harmonics reduction method, power factor correction and power quality improvement technique. The simulation and experimental results demonstrate that the proposed system reduce current type harmonics distortion and power quality improvement in efficient way. 1. INTRODUCTION AC-DC converters find application in everyday-life as a front-end to DC-DC and DC-AC converters. In low power with low cost applications, the AC to DC conversion is very often merely a diode bridge rectifier with capacitor voltage filter. However, bridge rectification inherently draws non-sinusoidal current from the mains, which make it inadequate for high power applications due to the strict regulations on conducted EM (electromagnetic) energy, as well as the high current stress on components. For high power applications, the sinusoidal current must be actively shaped by using either a boost type front-end converter or by complex EM filtering at the input. Research and development of the latter has ceased mainly due to the cost and size associated with EM filters. For medium power converters, a single-phase input is adequate and the front-end is usually a single-switch non-isolated boost topology that boosts the unregulated mains input to a voltage higher than the rectified line voltage. The switch is controlled in such a manner that the current drawn from the mains source is in phase with the mains voltage (effectively sinusoidal). The zero phase angle, between the mains voltage and the current, translates into a high power factor which, in turn, ensures that the source is not loaded reactively. For higher power outputs it is advantageous to use a three-phase input to lower the component stresses and to reduce component size (e.g. the filter capacitor). The three phase active rectifier is based on the concept of the single-phase active rectifier and draws sinusoidal current from all three phases. Controlled rectifiers are classified as being either isolated or non-isolated. For three-phase rectifiers, the non-isolated topologies are derived from the isolated topologies with the magnetic coupling (and thus isolation) achieved by