12-pulse Rectifier Research Articles

A novel pulse multiplication circuit for reducing harmonic distortion of 12 pulse rectifiers in aircraft electrical power systems

AbstractTo improve the performance and reduce the total harmonic distortion (THD) of the autotransformer 12‐pulse rectifier, a novel pulse multiplication circuit (PMC) based on two tapped inter‐phase reactors (TIPRs) is proposed to improve performance and reduce the THD of the autotransformer 12‐pulse rectifier. The proposed rectifier includes a phase‐shifting autotransformer based on a polygon connection, two 6‐pulse diode bridge rectifiers (DBRs), and a PMC. The novel PMC consists of two TIPRs (TIPR1 and TIPR2), an auxiliary single‐phase diode bridge (including four diodes D1 to D4), and two auxiliary diodes D21 and D22, which are connected directly to the output terminal of the DBRs (DBR1 and DBR2). The simulation and experimental results confirm the high capability of the proposed PMC to reduce the harmonic distortion of the input current, so that by using the proposed PMC, the input current is almost sinusoidal and the THD of the input current is less than 3%. Also, the results show that the proposed 12‐pulse rectifier meets the standard requirements of aircraft electrical systems (DO‐160G) without the need for any input and output filters.

Mitigation of harmonic distortions in third rail electrical systems

<span lang="EN-US">The extensive use of power electronic converters in the third rail system increases the harmonic distortions on the rail electrical feeding systems. Electrical machines and transformers could be overheated causing premature failures of the devices. It is therefore important to address the harmonic distortions on the electrical networks during real-time operation, which includes the degraded operation, not just the normal operation. In this paper, the harmonic distortions of a third rail system are investigated using electrical transient and analysis program (ETAP) simulation software. Four operating scenarios, namely the normal operation and three degraded operations, are considered in the studies. The degraded operations occur when one of the bulk supply transformers or 33 kV feeders is out of service. The findings of the studies showed that the 11<sup>th</sup> and 13<sup>th</sup> order harmonics are the dominant harmonic orders due to the use of 12-pulse rectifiers on the third rail system. Single-tuned harmonic filters are designed and placed in the 33 kV feeders to mitigate the individual voltage harmonic distortion (IHD<sub>v</sub>) and the total voltage harmonic distortion (THD<sub>v</sub>) so that it is within the statutory of IEEE 519:2014.</span>

Investigation on utilizing pulse CP in a city gas station: A comparison with conventional CP

In this study, a pulse Cathodic Protection (CP) rectifier was designed and made. The performance of the pulse rectifier was monitored and compared with a conventional system. In this regard, different values of duty cycle (73% and 50%) and frequency (50 kHz and 60 kHz) were analyzed. Results showed that the AC voltage and current consumption dramatically dropped compared to the conventional rectifier. Also, the pulse CP protection potential was distributed more uniformly as a function of pulse parameters in the optimum combination of 50 kHz and 73% for frequency and duty cycle, respectively. This was explained by the changes in the electrochemical polarization resistance of the environment when utilizing the pulse CP.

Research on multiple transient modeling scheme for full-cycle design of the 12-pulse PSR rectifier

PurposeThis paper aims to propose a novel multiple transient modeling scheme for the 12-pulse phase-shifting reactor (PSR) rectifier to enhance the efficiency of full-cycle design evaluation.Design/methodology/approachThe detailed time-domain method is adopted to model the rectifier at the behavioral layer. The diode bridges/transformer model at the architecture layer is established by using the switch function and Park transformation. The frequency domain model at the functional layer is derived with the time-varying Fourier decomposition and frequency-shifting. At the component layer, the magneto-thermal characteristics of the rectifier are analyzed with field-circuit and magnetic-thermal coupling methods. A computer-aided design program integrating multiple modeling is also developed for industrial product design.FindingsThe function layer modeling is preferred in the initial design stage, making up for the lack of modeling accuracy at the architectural layer and the lack of modeling rapidity at the behavioral layer. The component modeling is irreplaceable for the detailed evaluation in the latter design stage. The multiple modeling scheme based on the four-layer modeling helps the designers achieve high-quality products with a short development cycle.Originality/valueThe singular transient modeling cannot cover the needs of different stages in the full-cycle design evaluation. This paper fills this gap with a novel multiple modeling scheme. Meanwhile, the proposed multiple modeling scheme and developed computer-aided design program provide a great convenience for full cycle design evaluation of the 12-pulse PSR rectifier.

Input Current Step-Tripling for 12-Pulse Rectifier Using a Passive Four-Tap Changer

To effectively suppress the input line current harmonics of a 12-pulse rectifier under slightly complex hardware, this article proposed an input line current step-tripling scheme for a 12-pulse rectifier using a novel passive four-tap changer (FTC). The proposed FTC consists of a retrofitted four-tap interphase reactor (RFT-IPR) and four auxiliary diodes. Two auxiliary diodes are connected to the inner taps of the RFT-IPR, but the other two auxiliary diodes are connected to the outer taps of the RFT-IPR. The inner and outer auxiliary diodes modulate and increase the output current states of the rectifier bridges together first; then, the FTC extends the 12-step to 36-step input line current, and the near sinusoidal input current with 3% THD is obtained. The proposed FTC not only has a very low capacity (2.6% of the output power) but also does not require any active switching device aside from four auxiliary diodes; thus, the proposed scheme is a cost-effective, reliable, and efficient solution to harmonics pollution. An experimental prototype with an output power of 2.4 kW is built, and the correctness of the theoretical analysis is verified by the experimental results.

MATLAB simulation analysis of a 12-pulse rectifier circuit based on a power electronic transformer and its non-ideal state

The power electronic transformer structure can increase the output side voltage while reducing the volume of the transformer, which has the effect of increasing power density and expanding the DC side. Based on the current research and application of the PET rectifier modules. The 12-pulse rectification is not prone to failure in simple structures, so it is usually suitable for medium and high-power occasions. This article first introduces the rectifier topology model and its ideal waveform in an ideal state. Considering the actual situation of the power grid and power electronic transformers, there are phenomena of leakage inductance and magnetic flux leakage. This paper focuses on the non-ideal state to derive the theoretical formula and waveform derivation. And the 12-pulse rectifier circuit is modelled and simulated in MATLAB/Simulink. The main consideration is the simulation model of the 12-pulse rectifier section. In this study, a three-phase AC voltage is used to go in series with a three-phase winding transformer to equivalently replace the PET.

A Simple 36-Pulse Rectifier With Passive Pulse-Tripling Circuit at the DC Side

A series-connected 36-pulse rectifier with passive pulse-tripling circuit (PPTC) on the dc side is proposed in this article. The proposed rectifier consists of a series-connected 12-pulse rectifier and a PPTC. The PPTC includes a passive current forming network, a single-phase auxiliary transformer with dual secondary windings and two auxiliary single-phase rectifiers (ASRs). One ASR in PPTC is connected in series with the load to directly modulate the output current of rectifier bridges. The other ASR in PPTC is connected in parallel with the load to modulate the output current of rectifier bridges according to the relationship between its input voltage and load voltage. Composite modulation of the two ASRs increases the pulse number of the rectifier from 12 pulses to 36 pulses. The resulting rectifier obtains an approximate sinusoidal input current with less than 5% THD. Only a few low-capacity passive components are sufficient given the absence of active components in the proposed scheme. The proposed scheme presents advantages of simple circuit structure, easy implementation, and high reliability. Detailed analysis and experimental results are provided to verify the effectiveness of the proposed scheme.

Oversmoothing Relief Graph Convolutional Network-Based Fault Diagnosis Method With Application to the Rectifier of High-Speed Trains

In the conventional graph convolutional network (GCN)-based fault diagnosis method, multilayer GCN model is often used for feature extraction. However, the application of multilayer GCN will encounter oversmoothing problem, and thus reduce the diagnostic performance. Therefore, the oversmoothing relief GCN (OsR-GCN) method is proposed. Specifically, two association graph construction methods, namely the Euclidean distance (ED)-based method and the structure analysis (SA)-based method, are first introduced. Then, the constructed graph and measurements are input to the OsR-GCN model, in which a weight coefficient is proposed to relieve the oversmoothing problem. Next, an improved particle swarm optimization algorithm is introduced to find the optimal weight coefficient. Finally, the proposed method is applied to diagnose the pulse rectifier faults in a hardware-in-the-loop simulated traction control system of high-speed trains. The achieved results show that the proposed method outperforms the existing fault diagnosis methods.

Hybrid Harmonic Suppression at DC Side for Parallel-Connected 12-Pulse Rectifier

Hybrid Harmonic Suppression at DC Side for Parallel-Connected 12-Pulse Rectifier

Harmonic Analysis of A DC Railway Traction with Uncontrolled 12 Pulse Rectifier

In the topology of the DC traction substation there is a rectifier component which generally uses a 12 pulse rectifier type and the load is in the form of a trainset with a component in the form of a converter used for variable speed drives (VSD). The operation of the rectifier and the VSD converter load causes harmonics to appear on the AC input side, so anticipation needs to be done. Therefore, it is necessary to conduct an assessment related to DC traction substations to obtain good electrical power quality. The purpose of this study was to determine the electric power quality parameters of DC railway traction using a 12 pulse rectifier and a VSD converter load. This research was conducted by simulating a DC railway traction model with a 12 pulse rectifier and knowing the comparison of the system power quality between the VSD converter load and the resistive load as the basic reference for the traction substation work system of this model. System modeling is done using PSIM software. The results of the simulation are the parameters of the stability of the voltage, current, and system harmonics.

Negative Impact Mitigation on the Power Supply System of a Fans Group with Frequency-Variable Drive

The technological installations’ characteristics are possible to improve by equipping fans with a frequency-controlled electric drive. However, it can lead to an electromagnetic compatibility problem in the electrical supply system. This problem becomes worse if a large number of fans are included in the technological installation and the electric drives are powered from a substation connected to a limited power source. As an example, in this article we investigate the power supply system of a gas cooling unit with variable-frequency electric drives for fans. The electric drives’ operating mode dependences characterizing the non-sinusoidal voltages and currents of the power source are obtained with the help of simulation modeling in the MATLAB environment with the Simulink expansion package. The typical substation circuit usage for the power supply of a group of fans with a frequency-controlled drive does not meet the requirements of IEEE Standard 519-2014. We can solve the problem of electromagnetic compatibility by changing the substation topology and organizing DC busbars and replacing frequency converters with inverters. We proposed forming DC busbars using 12-pulse rectifiers powered by transformers with two secondary windings with different connection schemes. The simulation results confirmed that the proposed substation topology provides the voltage and current harmonics level on the substation power busbars in accordance with the IEEE Standard 519-2014 requirements over the entire frequency range of the fans’ motor control.

A Parallel-Connected 24-Pulse Rectifier Using Hybrid Harmonic Reduction Method at DC Side

This letter proposes a parallel-connected 24-pulse rectifier using a hybrid harmonic reduction method at the dc side. The proposed rectifier contains an unconventional interphase reactor (UIPR) with a double-tapped primary winding and secondary winding connected pulsewidth modulation converter. The proposed method is a combination of the passive and active harmonic method. From the viewpoint of total harmonic distortion (THD) of the input line current, ripple load voltage, and kilovoltampere rating of the active auxiliary circuit, the UIPR and active injecting current are optimally designed. An experimental prototype is developed to verify the theoretical analysis. The experimental THD is about 2.87%, which shows good performance of harmonic reduction.

Harmonic generation of variable speed drive under complex-voltage unbalance conditions

Efficiency in the industrial sector is a priority when seeking to minimize production costs and reduction in losses. Harmonic generation and associated losses need to be treated carefully with broad implementation of variable speed induction motor applications. The effect of these induced losses can add up to a significant loss. This study uses statistical tools alongside synthesized models to deduce and compare outcomes from regulated and unregulated converters in which harmonics may be triggered by switching algorithm of modern switch-mode power supplies and other inductive loads attached to supply bus system. These harmonics accumulate over time due to losses propagating through connected equipment when changes occur on the bus system. In this regard, results obtained from investigating and comparing three original equipment manufacturer variable speed drives that were exposed to voltage unbalance and complex harmonic conditions are presented in this study. A conclusion accomplished from the investigation and comparison suggests that generation of 6-pulse uncontrolled rectifier losses is negligible. Experimental validation confirms that unregulated 6-pulse converter produces on average more harmonics compared to the regulated converter of standard as recommended in guideline to permissible harmonic tolerance.

An energy-based control scheme for optimal power quality management in 12-pulse rectifier integrated distribution systems

This paper proposes an energy-based control scheme for optimal power quality management in 12-pulse rectifier integrated distribution systems. In this 12-pulse rectifier integrated distribution system, instead of using a step-down transformer for voltage matching, a back-to-back converter is connected to the taps of star and delta windings on 12-pulse rectifier transformer’s secondary side via the coupling LC. Using the magnetic potential balance of harmonics and reactive components between the back-to-back converter and the load side of the 12-pulse rectifier, the power quality of distribution systems can be managed. This topology can improve the voltage and current adaptability of the converter, thereby saving the cost of voltage matching transformer and exploiting the filter converter capacity potential. To ensure global power quality performance, an energy-based control scheme is proposed to improve the power quality management performance by accelerating the energy dissipation of the system. Case studies are performed to verify the effectiveness and superiority of the proposed methodology on low dc-link voltage and power quality.

A 24-Pulse Rectifier With a Passive Auxiliary Current Injection Circuit at DC Side

In this article, a simple series-connected 24-pulse rectifier with a passive auxiliary current injection circuit (ACIC) is proposed. The proposed rectifier consists of a 12-pulse rectifier and an ACIC. The ACIC includes a circulation current forming circuit, an auxiliary single-phase transformer (AST), and an auxiliary single-phase full-bridge rectifier (ASFR). The ASFR extracts alternating square-wave current from the dc side and injects it into the outputs of three-phase rectifier bridges to increase the output state of these bridges. The operating mode of the proposed rectifier is analyzed, and the functional relationship between the input current and turns ratio of AST is established. The AST turns ratio that minimizes the input line current total harmonic distortion (THD) is derived. The voltage and current rating of AST are calculated, and the design method of capacitors C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> in ACIC is given. Under the optimal turns ratio, the ACIC extends the 12- to a 24-pulse rectifier. The resulting 24-pulse rectifier draws near-sinusoidal input currents with less than 5% THD. The AST in ACIC has a very low kilovolt-ampere rating (1.96% <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ), and the current ratings of ASFR are small. The theoretical analyzes are provided and experimentally verified using a 1.7 kW experimental prototype.

Multi-Level Transient Modeling of the Aeronautic Asymmetric 18-Pulse Phase-Shifting Auto-Transformer Rectifier in Full-Cycle Design

The higher failure rate of the rectifier unit severely affects the reliability of the more electric aircraft (MEA). In order to provide an insight into the electrical and magneto-thermal behavior in the full-cycle design evaluation, a novel multi-level modeling scheme for the aeronautic asymmetric 18-pulse dynamic phasor (DP)-type phase-shifting auto-transformer (PS-AT) rectifier is proposed in this article. The behavioral level modeling is built up to reveal the electrical characteristics since the ontology parameters are designed for the 18-pulse PS-AT, where the computation non-convergence posed by matrix singularity is alleviated by improving the condition number. Besides, the DP model crossing architecture level and functional level is proposed by transforming the nonlinear electrical variables in the time domain into the frequency domain with time-varying Fourier decomposition and frequency shift. To illustrate the comprehensive electrical and magneto-thermal characteristics of the 18-pulse PS-AT rectifier at the component level, field-circuit coupling, and magneto-thermal coupling with the finite-element method (FEM) are adopted. Furthermore, simulations of the 18-pulse PS-AT rectifier system are also carried out, to validate the simulation accuracy and computation efficiency of the proposed multi-level modeling scheme. An aided design program integrating the multi-level modeling methods is also developed to help designers achieve high-quality products with a short development cycle.

A Novel 36-pulse rectifier with low kVA rate to reduce harmonic input current distortion

A Novel 36-pulse rectifier with low kVA rate to reduce harmonic input current distortion

Suppression of Ripples of Controllable Rectifiers for Power Supply of Magnetic Systems

A number of requirements are imposed on installations associated with regulated DC sources, including low voltage and current ripple in the load, as well as a wide range of output current variation. Such installations are traditionally made on controlled rectifiers or pulse-width converters in which voltage ripples are always present. The paper considers a method for reducing the voltage ripple of powerful rectifiers for powering magnetic systems based on the insertion of a compensating voltage equal in magnitude and opposite in phase to the ripple voltage into the load circuit. The possibility of using ripple compensators connected in parallel and in series with the load, as well as methods of obtaining a compensating voltage is shown. Methods for obtaining compensating voltage are given. In order to exclude the magnetization of the ripple compensator transformer, it is proposed to use several versions of the compensating transformer and the inclusion of ripple compensators. Practical schemes of passive compensators (with a demagnetizing circuit and a bifilar winding) are analyzed. The problem of developing ripple compensators for multiphase rectifiers, as well as ways to solve it, is considered. Practical recommendations for choosing a core material and calculating a transformer are given. On the basis of the presented theoretical and practical considerations for the design of the ripple compensators, simulation models have been developed in the Simulink pack-age of the MATLAB program. A technique for studying ripple compensators using the simulation models of a symmetrical 12-pulse rectifier that has been developed is presented. The results of simulation of passive ripple compensators, performed in two versions, showed their effectiveness, while the scheme was relatively simple and economic costs were relatively low. Also, the time of setting the set current in the system in the presence of a ripple compensator increases by no more than 3 %, and the accuracy and stability of operation do not change.

Heuristic Optimization of Multipulse Rectifier for Reduced Energy Consumption

Intelligent Manufacturing 5.0 of multipulse rectifier systems requires them to be optimized for a variety of use in transportation and factories producing hearty touch technology. The research presented in this article show advances of using heuristic models to set 12-pulse and 24-pulse rectifiers to work under low- and high-voltage load. As a result of heuristic optimization electric systems increase efficiency and reduce energy consumption by efficiency benefits in adopting artificial intelligence. Applied heuristic models helped in computer simulations to optimize system settings in a short time. Results show that optimized models are more efficient and our proposed approach is reducing voltage pulsation. As a result optimized system improves electromagnetic compatibility for beneficial use in modern industry and sensible human–machine cooperation.

Input Current Step-Doubling for Autotransformer-Based 12-Pulse Rectifier Using Two Auxiliary Diodes

To significantly decrease the input line current total harmonic distortion (THD) under simple circuit configuration conditions, this article propose an input current step doubling scheme for autotransformer-based 12-pulse rectifier using two auxiliary diodes. The auxiliary diodes are installed between the two retrofitted double-tap interphase reactors, and they inject specific square wave currents to increase the output current states of the rectification bridges. This modification extends the 12-step input line current to a 24-step input line current, and the near sinusoidal input line current with THD below 5% is obtained. As the proposed scheme only requires two low current stress (3.4% <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> ) auxiliary diodes, it achieves high-cost performance, is easy to implement and has a simple circuit configuration. A 2.2 kW simulation and experimental prototype is built to verify the theoretical analysis.