ENHANCED THREE PHASE AC/DC/AC CONVERTER TO MINIMIZING THE TOTAL CURRENT HARMONICS (original) (raw)
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Reduction of total harmonic distortion of three-phase inverter using alternate switching strategy
International Journal of Power Electronics and Drive Systems (IJPEDS), 2021
Alternating current (AC) electrical drives mainly require smaller current (or torque) ripples and lower total harmonic distortion (THD) of voltage for excellent drive performances. Normally, in practice, to achieve these requirements, the inverter needs to be operated at high switching frequency. By operating at high switching frequency, the size of filter can be reduced. However, the inverter which oftenly employs insulated gate bipolar transistor (IGBT) for high power applications cannot be operated at high switching frequency. This is because, the IGBT switching frequency cannot be operated above 50 kHz due to its thermal restrictions. This paper proposes an alternate switching strategy to enable the use of IGBT for operating the inverter at high switching frequency to improve THD performances. In this strategy, each IGBT in a group of switches in the modified inverter circuit will operate the switching frequency at one-fourth of the inverter switching frequency. The alternate switching is implemented using simple analog and digital integrated circuits.
Analysis & Comparison of Harmonics Reduction Topologies for Three Phase Bridge Inverter
— This paper describes analysis and comparison of three different topologies for reduction of harmonic contents in three phase bridge inverter with 180 degree mode of conduction. IEEE standard 519-1992 is a useful document for understanding harmonics and applying harmonic limits in power systems. Three different topologies are basic inverter operation with no harmonics reduction, second is passive filter by using combination of inductor-capacitor elements (LC circuit) and third is pulse width modulation technique. Here in this paper sinusoidal pulse width modulation technique is explained. Three circuits are simulated in MATLAB simulink for harmonics analysis in fast Fourier transform (FFT). Out of Three topologies sinusoidal pulse width is best method for reduction of harmonics. Level of harmonics is analysed using Total harmonic Distortion (THD).In addition to this work Active Filter circuit can also be used to minimize the THD level by implementing series active filter for current waveform and shunt active filter for voltage waveform for three phase circuit.
Electric Power Systems Research, 2009
This paper presents a new approach to eliminate harmonics and to improve power factor of a three phase front-end uncontrolled rectifier. A high-power-factor is achieved by injecting high-frequency triangular current from the output of three-phase inverter. The high frequency (HF) current modulates the rectifier input voltage resulting in conduction of diodes into each switching cycle. The resulting ac input line current is continuous and sinusoidal in shape with significant reduction in current harmonics. All the switches are operated at zero-voltage switching (ZVS). The diodes of the rectifier are also operated with soft switching at turn-on as well as at turn-off. Varying switching frequency with fixed duty ratio regulates the output voltage. The proposed ac-to-dc converter also maintains high-power-factor even for unbalanced input supply voltages. The analysis of the converter is carried out on a single-phase basis, using different operating modes in one switching cycle of injected current. Theoretical results based on analysis are verified initially through digital simulation, and confirmed by using an experimental prototype of 2.5 kW.
This is a well-known fact that during a transformerrectifier combination undesirable harmonic line currents may be generated. The rectification of alternating current power to direct current power itself may produce undesirable current harmonics. The non-linear loads cause the severe current harmonics that can not be tolerated. These harmonic currents can cause either a shutdown of the device or the unacceptable powering of the devices. The non-isolated multi-pulse converters and the Multi-pulse converters in general can be applied to achieve the clean power which is of major priority in higher power rating applications. Generally, by increasing the number of pulses in a multi-pulse converter THD (total harmonic distortion) can be reduced up to the allowable limits. Thepresentwork istoanalyses the differentmulti-pulse AC toDC (18-pulse, 24-pulse, 36-pulse, and 48-pules) converters insolvingthe harmonic problem in athree-phase converter system. The effect of increasing the number of pulses on the performance of ac-dc converters is analyzed. THD is the major factor considered for the performance comparison of various converters.
Evaluation of various converters for decreased total harmonic distortion and progressed Power Factor
2018
energy electronics is a enormous region in electrical engineering for research which incorporates different switching gadgets to manipulate and switching of electrical machines and drives for his or her output, velocity and torques and so forth. it has many programs in our ordinary life together with motor drives, and energy resources for pc. the ‘modern’ drawn by means of those devices is distorted so there is a need to use electricity element correction converter. on this paper a comparative evaluation of different topologies of ac–dc converter is completed for total harmonic distortion and enriched energy factor. the model is simulated in matlab and their outcomes are proven. Keywords—THD; PFC; PFC Boost Converter; PFC Double Boost Converter.
Digital implementation of harmonics reduction of three-phase boost rectifier
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The line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components to the control signal of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this paper a digital implementation of injecting six harmonic to the control signal of three-phase boost rectifier is shown. The digital implementation is carried out by using FPGA. In this study a sin-wave and a triangle-wave with six times the fundamental frequency and variable amplitude are digitally generated in the FPGA. Each signal is added to the dc control signal component of boost converter to be compared with digitally generated saw-tooth. The simulation and experimental results show that the THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the control signal of the boost converter and the angle of input three-phase voltage.
A Novel Harmonic Reduction Technique for Controlled Converter by Third Harmonic Current Injection
Three-phase controlled converter has many applications in interfacing renewable energy sources and adjustable speed drives as a rectifier or inverter. The utility line currents of this converter have high harmonic distortion more than the harmonic standards. This research introduces a new technique of circulating third harmonic currents from dc link to the line currents to reduce its harmonic contents. The new proposed system uses single-phase controlled converter to control the angle of injection current for each firing angle of the three-phase converter. A detailed analysis is introduced to achieve a relation between the firing angles of three and single-phase controlled converters. Also a detailed design for other injection path components is introduced. A simulation and experimental work is introduced to prove the mathematical derivations. Analysis, simulation and experimental results prove the superiority of the proposed technique. Index Terms-Three-phase controlled converter, harmonic distortion, third harmonic injection, power quality. Nomenclature If Third harmonic injection current. v", ia The voltage and current of phase o. a The firing angle of three-phase converter. {Jon The angle of Von,3 referred to Va in 180 Hz domain. qJ The angle between Von,3 , and If in 180 Hz domain. qJopt The angle between Von,3 , and If for minimum THD in line currents in 180 Hz domain. (/) The angle between V a and If in 180 Hz domain. (/) opt The angle between V a, and If for minimum THD in line currents in 180 Hz domain. Vm The peak value of phase voltage, w The angular velocity of the fundamental frequency. VLL The rms value of line to line supply voltage Vdn,3k The rms value of (3k) harmonic of the voltage between points d and n. V f n,3k The rms value of (3k) harmonic of the voltage between points/and n. Von,3k The rms value of (3k) harmonic of the voltage between points a and n.
Investigation of Total Harmonic Distortion of a Three-Phase Cúk Rectifier
Rectification is a very common term in power electronics sector, where an AC signal is converted into a DC signal. But this process comes up with few problems, such as, distortion of input current. With high amplitude, the total harmonic distortion (THD) increases. To solve these problems, passive filtering is used to decrease harmonic distortion and to improve the nature of input current. But filtering brings lower output voltage. To solve this problem, output filtering is used with the DC-DC regulator. In this paper, the input side current of a three phase Cúk rectifier is improved with respect to output voltage level, efficiency and optimum total harmonic distortion using passive filters and PWM technique. Simulation results are presented to show the effectiveness of the design.
Harmonics reduction of three-phase boost rectifier by modulating duty ratio
Electric Power Systems Research, 2007
Line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components from the DC bus back to the duty ratio of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this study a sine wave and a triangle wave with six times the fundamental frequency is presented. The analysis has been carried out to reduce THD of the utility line current of three-phase boost rectifier. The THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the duty ratio of the boost converter. A complete mathematical and simulation analysis of the injection technique has been carried out. The mathematical analysis and simulation results of 6 kW prototype system show the superiority of the proposed injection technique.
Analysis of Different Converters for Reduced Total Harmonic Distortion and Improved Power Factor
— Power electronics is a vast area in electrical engineering for research which includes different switching devices to control and switching of electrical machines and drives for their output, speed and torques etc. It has many applications in our everyday life such as motor drives, and power supplies for computer. The 'current' drawn by these devices is distorted so there is a necessity to use power factor correction converter. In this paper a comparative evaluation of different topologies of AC–DC converter is completed for Total Harmonic Distortion and enriched power factor. The model is simulated in MATLAB and their results are shown.