Multipulse AC-DC Converters Research Articles

Investigating the input power quality of multi-pulse AC-DC power converter fed induction motor drives

Optimization of supply current total harmonic distortion (THD) of multi-pulse AC-DC power converter fed induction motor drive (IMD) is always a challenging issue. Higher amount of supply current THD degrades the input power quality of IMD. The supply current THD should be controlled in such a way so that it adheres the power quality standard of IEEE-519. With the increase of the pulse number of multi-pulse AC-DC converter, supply current THD increases. In this work, an investigation has been carried out on 6-pulse, 12-pulse, 18-pulse, and 24-pulse AC-DC power converters based IMD. A thorough analysis of input current profile, THD, dynamic responses including stator current, speed, torque profile of the induction motor are highlighted in this work with the various load perturbation conditions. This work will provide a message to the industrial community about the proper selection of AC-DC power converter for IMD application considering power quality and circuit configuration issues. All the investigating works are conducted in MATLAB/Simulink platform.

Systematic Implementation of Multi-Phase Power Supply (Three to Six) Conversion System

Multiphase (more than three) power system has gained popularity due to their inherent advantages when compared to three-phase counterpart. Multiphase power supply is extensively used in AC/DC multi-pulse converters, especially supply with multiple of three-phases. AC/DC converter with multi-pulse input is a popular solution to reduce the ripple in the DC output. Single-phase and three-phase transformers and phase transformation from single to multiphase are employed in variable speed drives application to feed the multi-cell H-Bridge converters and multi-pulse AC-DC converters. Six-phase system is extensively discussed in the literature for numerous applications ranging from variable speed drives to multiphase wind energy generation system. This paper shows the systematic phase transformation technique from three-phase to six-phase (both symmetrical and asymmetrical) for both understanding and teaching purposes. Such an approach could help students understand a promising advanced concept in their undergraduate courses. When phase difference between the two consecutive phases of six phases has a phase difference of 60°, it is called a symmetrical six-phase system; while an asymmetrical or quasi, six-phase has two set of three-phase with a phase shift of 30° between the two sets. Simulation and experimental results are also presented.

Multi‐pulse AC–DC converter fed SVM controlled NPC inverter based VCIMD

A multi-pulse AC-DC converter fed space vector modulation (SVM) controlled neutral point clamped (NPC) inverter based vector control induction motor drive (VCIMD) is proposed here for medium power rating applications. To improve the power quality at supply side, a 12-pulse AC-DC converter is used and to meet the IEEE-519 standard, a high-pass filter is also used along with it. A three-level NPC inverter is utilised on the motor side to enhance the required performances of an induction motor drive (IMD). A modified SVM strategy is proposed to balance the capacitor voltages of the NPC inverter and to switch this inverter at very low switching frequency. The neutral point voltage balancing is achieved by the time adjustment between positive and negative small vectors. The model of proposed IMD is developed using the Simulink/MATLAB platform, and simulated response is validated with test results on a developed prototype in the laboratory to demonstrate its usefulness for medium power applications.

Harmonic reduction using a novel multipulse AC-DC converter

PurposeFor direct torque controlled induction motor drives, an effective solution to eliminate harmonics is the use of multipulse alternating current (AC)-direct current (DC) converters. Many researchers have used different configurations based on 24- and 30-pulse rectifications for improved power quality. However, the total harmonic distortion (THD) of AC mains current with these topology is more than 4 per cent when operating at a light load. For mitigating the THD problems observed in the input currents, Abdollahi propose 40-, 72- and 88-pulse AC-DC converters, while the power quality enhancement was the main concern. It is known that by increasing the number of pulses further results in reduction in current harmonics, but this is accompanied by an increase in cost and complexity. In this context, the purpose of this paper is to design a new delta/hexagon transformer based 36-pulse AC-DC converter for harmonic reduction without increasing the cost and complexity.Design/methodology/approachThe proposed converter consists of two paralleled 18-pulse AC-DC converters involving a nine-phase shifted uncontrolled diode bridges with an interphase transformer circuit.FindingsIn this paper, the proposed scheme is simulated by matrix laboratory (MATLAB)/SIMULINK considering different loading scenarios. The simulation results show that the proposed scheme improves the power quality indices and satisfies the The Institute of Electrical and Electronics Engineers (IEEE)-519 requirements at the point of common coupling. Also, a laboratory prototype is implemented using the proposed design, and the experimental results confirm the simulation results under different loading conditions.Originality/valueThe proposed solution is a tradeoff among the pulse number, the transformer platform, the complexity of the scheme and the cost. The proposed scheme has an optimized configuration in this regard.

Comparison of power quality indices and apparent power (kVA) ratings in different autotransformer-based 30-pulse AC–DC converters

Three-phase multipulse AC–DC converters (MPC) are developed for improving power quality to reduce harmonics in ac mains and ripples in dc output. This study, based on technical and economic factors, compares different autotransformer-based 30-pulse AC–DC converters. In thispaper, the comparison of two topologies of autotransformer-based 30-pulse AC–DC converter has been presented. In topology A, three-phase AC voltages are given to the autotransformer, which produces five sets of three-phase voltage and, in topology B, three-phase AC voltages are given to the autotransformer, which produces three sets of five-phase voltages of same magnitude and distributed in time through phase shifts of 12◦ . Topology A included polygon, hexagon, star, fork, and T-connected autotransformer-based 30-pulse AC–DC converters, and topology B Included polygon, and T-connected autotransformer-based 30-pulse AC–DC converters. These converters have been implemented and simulation using Matlab/Simulink software for similar ratings under different load conditions has been performed. A set of power-quality indices on input ac mains and on a dc bus for a DTCIMD fed from different 30-pulse AC–DC converters is given to compare their performance. Economic comparison of 30 pulse AC–DC converters is based on the apparent power (kVA) ratings of the different autotransformer for 30 pulse AC–DC converters.

Power quality improvement by using multi-pulse AC-DC converters for DC drives: Modeling, simulation and its digital implementation

The paper presents the modeling, simulation and digital implementation of power quality improvement of DC drives by using multi pulse AC–DC converter. As it is a well-known fact that power quality determines the fitness of electrical power to consumer devices, hence an effort has been made to improve power quality in this work. Simulation and digital implementation with the help of MATLAB/Simulink has been done and results obtained are discussed in detail to verify the theoretical results. The multipulse converter was connected with DC drives and was run at no load condition to find out the transient and steady state performances. FFT analysis has been performed and Total Harmonic Distortion (THD) results obtained at different pulses are shown here.

Power quality improvements employing multipulse full-wave AC-DC converters

In this paper, a set of full-wave AC-DC converters are investigated for power quality improvement in AC mains and DC output. A detailed classification of these full-wave AC-DC converter configurations is made in different transformer connections and several new configurations of isolated and non-isolated full-wave AC-DC converters are developed to meet specific application requirements. The isolated full-wave converters are well-known for low-voltage high-current applications; however, non-isolated full-wave AC-DC converters are not known, mainly due to the popularity of bridge-based configurations and therefore investigated in this paper. These full-wave converters in six-pulse, 12-pulse, 18-pulse and 24-pulse are designed, modelled and simulated to compare their performance in terms of power quality parameters. The validation of design of these converters is carried out through test results on developed prototypes.

Harmonics Mitigation in LCI-Fed Synchronous Motor Drives

A load-commutated inverter (LCI) fed synchronous motor (SM) is operated as an adjustable speed drive (ASD) in high-power applications. These drives are known as commutatorless motor (CLM) drives and posses many promising features like high efficiency, economic operation, and flexibility of control in high-power ratings. The CLM drives are used in compressors, blowers, fans, pumps, and mill drives for a range of industries as mining, water treatment plants, chemical, paper, textile, cement, rolling mills, and petrochemical plants. However, the power quality (PQ) problems at ac mains have been the concerns in these drives as the LCI has front-end thyristor converter injecting harmonics in the supply. This paper investigates various topologies for the mitigation of PQ problems in LCI-fed SM drives using multipulse ac-dc converters. A set of hybrid topologies is proposed, which use a combination of a passive filter with a multipulse converter to feed CLM. A basis for selection of a suitable ac-dc converter is presented for PQ improvement at the input mains of the LCI-fed SM drives.

Power quality improvement in load commutated inverter-fed synchronous motor drives

The load commutated inverter (LCI)-fed synchronous motor (SM) drive, also known as commutatorless motor (CLM) drive, is popular in high power applications. Most promising features of these drives include high efficiency, economic operation, flexibility of operation and variable speed in high power range, which led to their applications in blowers, fans, pumps, mill drives for a range of industries as mining, water treatment plants, chemical, paper, textile, cement, rolling mills and petrochemical plants. However, the power quality (PQ) concerns have resulted in a set-back for such applications of these drives. This study investigates various topologies for the mitigation of PQ problems in LCI-fed SM drives using multi-pulse AC-DC converters. A set of hybrid topologies is proposed to feed CLM, which use a multi-winding transformer and diode rectifiers with a chopper cascaded named as -rectifier-chopper-. These topologies improve PQ at AC mains, that is, reduce total harmonic distortion in the input current and correct the power factor. It also presents a basis for selection of a suitable AC-DC converter for PQ improvement at the input AC mains of the LCI-fed SM drives.

Power quality improvement in vector controlled induction motor drive employing multipulse AC-DC converters

In this paper, the power quality performance is investigated from hardware implementation of vector controlled induction motor drive (VCIMD) having multipulse AC-DC converter at front-end. The power quality issues are analysed for 12-pulse, 24-pulse and 40-pulse non-isolated, uncontrolled multipulse AC-DC converters. The vector control of a voltage source inverter (VSI) fed induction motor drive is modelled in MATLAB environment using Simulink and Power System Blockset toolboxes. The results obtained from the simulations are presented along with the hardware test results. It is observed that the AC mains current THD having value less than 3% in VCIMD is possible employing multipulse AC-DC converters.

Power quality improvement in vector controlled induction motor drive employing multipulse AC-DC converters

In this paper, the power quality performance is investigated from hardware implementation of vector controlled induction motor drive (VCIMD) having multipulse AC-DC converter at front-end. The power quality issues are analysed for 12-pulse, 24-pulse and 40-pulse non-isolated, uncontrolled multipulse AC-DC converters. The vector control of a voltage source inverter (VSI) fed induction motor drive is modelled in MATLAB environment using Simulink and Power System Blockset toolboxes. The results obtained from the simulations are presented along with the hardware test results. It is observed that the AC mains current THD having value less than 3% in VCIMD is possible employing multipulse AC-DC converters.

A 24-pulse AC-DC converter employing a pulse doubling technique for vector-controlled induction motor drives

This paper deals with various multipulse AC-DC converters for improving the power quality in vector-controlled induction motor drives (VCIMDs) at the point of common coupling. These multipulse AC-DC converters are realized using a reduced rating autotransformer. Moreover, DC ripple reinjection is used to double the rectification pulses resulting in an effective harmonic mitigation. The proposed AC-DC converter is able to eliminate up to 21st harmonics in the supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC-DC converter. A set of power quality indices on input AC mains and on the DC bus for a VCIMD fed from different AC-DC converters is also given to compare their performance.

Multipulse AC–DC Converters for Improving Power Quality: A Review

Three-phase multipulse AC-DC converters (MPC) are developed for improving power quality to reduce harmonics in AC mains and ripples in DC output. This paper deals with the multipulse AC-DC converter configurations, state of art, their performance, power quality aspects, components selection considerations, latest trends, future developments, and potential applications. It is targeted to provide broad perspective on multipulse converter technology to the researchers, engineers, and designers dealing with them. A classified list of more than 250 research publications on the subject is also given for quick reference.

24-Pulse AC-DC Converter for Power Quality Improvement in Vector Controlled Induction Motor Drives

This article deals with autotransformer based multipulse AC-DC converters feeding vector controlled induction motor drives (VCIMDs) for improving power quality at the point of common coupling (PCC). The proposed 24-pulse AC-DC converter is realized on the principle of DC ripple re-injection technique for pulse multiplication and harmonic mitigation. The design of the autotransformer is given for the proposed AC-DC converter for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC-DC converter. The test results, along with simulated results, on a developed laboratory prototype are presented to validate the design and model of the proposed 24-pulse AC-DC converter.