Three-phase Converter Research Articles

Motor Driver-Based Topology of Integrated On-Board Charging System and Data-Driven Inductance Identification Method

This paper presents a topology of integrated on-board charging system with separated inductors on grid side. It employs the on-board three-phase electric power converter in time-division multiplexing, and separates the grid side inductors from the vehicle, reducing volume, weight and cost of the on-board charging system. To provide an accurate inductance for the control system, a data-driven inductance identification method is proposed. The inductance is first identified at the uncontrolled rectification stage, then the real-time online inductance correction is further implemented at the PWM rectification stage. In addition, the operating principle and structural characteristics of the proposed topology are discussed, and the inductance identification method is analyzed in detail. Finally, a 2 kW experimental prototype is built to validate the correctness of the theoretical analysis and effectiveness of the proposed identification method applied to the proposed topology in this paper.

Current-Sharing Worst-Case Analysis of Three-Phase CLLC Resonant Converters

Three-phase CLLC resonant converters provide higher power conversion capability compared to half-bridge and full-bridge structures. In addition to the unique features of CLLC converters for bi-directional applications, the three-phase structure provides significantly reduced output current ripple (smaller output capacitor), parallel power processing (reduced components size and current peak stress), and better thermal distribution (smaller heatsinks). However, with practical, i.e. non-zero, resonant component tolerances, these benefits are normally less, and sometimes significantly less than expected in the ideal case. In this paper, the unbalanced behavior of the converter with fifteen unknown resonant components is identified and analyzed. A new analysis methodology is proposed to investigate the worst-cases of current-sharing among above 32000 possible scenarios in three-phase CLLC resonant converters. In addition, the paper shows that phase-shifting techniques can be effective to mitigate the unbalanced behavior of the converter. The proposed analysis in this paper helps to determine the highest admissible tolerance in the components to keep the converter working within a certain range of unbalanced behavior without requiring any balancing techniques. The proposed analytical framework is verified with experimental and simulation results of a 3-kW bidirectional three-phase CLLC experimental prototype.

Open and Short Circuit Post-Fault Control Strategies for Multi-Three-Phase Interior Permanent Magnet Machines

This paper presents a post-fault current control strategy for dual three-phase Interior Permanent Magnet (IPM) synchronous machines. The current controllers are designed based on the Vector Space Decomposition (VSD) algorithm. This take into account the equivalent harmonic inductance variation, which is then used to introduce the post-fault compensation control. A double three-phase IPM machine is modelled and operated in three different operating conditions: nominal, one three-phase set in short-circuit (SC), and one three-phase set in open-circuit (OC). By keeping the current loop bandwidth constant, the proposed fault-tolerant current controllers guarantee the same dynamic performance of the remaining healthy module after the faults occurred. In OC fault, the proportional and integral (PI) controllers are re-designed while adapting the inductance variation. For the SC case, constant stability margins are provided by cascading a novel lag compensator to the nominal controller. The current dynamics responses are analysed in both healthy and faulty conditions by means of Matlab/Simulink simulations. Experimental results on a 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf {kW}$</tex-math></inline-formula> six-phase IPM machine prototype with isolated neutral points and supplied by two custom three-phase converters, are demonstrating the effectiveness of the proposed control strategies.

Reconfigurable Multi-Three-Phase Drive for Naval Rim-Driven Propulsion System

Multiphase drives are the subject of great interest for the transportation electrification. Multi-three-phase machines are used with modular three-phase converters to obtain a redundant structure and their great advantage is the fault-tolerance capability. Starting from a symmetrical multi-three-phase machine, a reconfigurable architecture drive can be obtained. The main characteristic of a reconfigurable architecture is the ability to change the winding configuration to better match the operating point, specifically the machine speed. The main advantage of this architecture is the capability of reducing the number of active converters when the machine operates at low speed, thus reducing total converter power losses. However, system complexity increases, since reconfiguration cells are needed to interconnect the winding sets. The proposed reconfigurable multi-three-phase drive architecture exhibits two main benefits at low speed operation: increased efficiency and reduced phase current ripple for a given switching frequency. The reconfigurable architecture was assessed by means of analytical as well as numerical simulations, and the benefits obtainable at low speed operation were also demonstrated experimentally on a reduced scale prototype, capable of “on the fly” reconfiguration without stopping the machine.

ARTIFICIAL INTELLIGENCE BASED ON THE OPTIMAL STRATEGY OF MULTILEVEL CONVERTER FOR BRUSHLESS DC MOTOR

This paper presents an interesting novelty in the implementation of artificial intelligence (AI) to apply multi-level converter control, the best strategy for the Brushless DC motor control (BLDC). The interesting highlight of this research is the importance of bringing artificial intelligence (AI) to develop multi-level converter mechanisms using the artificial neural network algorithm. The neural network is a branch of artificial intelligence and is used to detect the magnitude of the input voltage from batteries. The operation of this DC-DC voltage conversion mechanism detects the output voltage and current to control the operation of the multi-level conversion mechanism supplied with six switched three-phase converters (SSTPC) to the BLDC motor controller. For this BLDC motor control mechanism, the neural network algorithm detects the Hall Effect signal to generate a PWM signal to control the action of the SSTPC. Notwithstanding, the prototype mechanism of this research is divided into two parts, the first being the conversion control mechanism multi-level, which is an essential part of voltage regulation. The second is the BLDC motor torque and speed control mechanism. This torque and speed control uses the Hall Effect signal detection principle and processes it with a neural network algorithm to generate a PWM signal to control the SSTPC activity. This neural network algorithm is processed with a DSP-TMS320C2000 microcontroller. However, the results of the prototype mechanism tested; found the importance of artificial intelligence (AI) for developing multi-level conversion mechanisms using artificial neural network algorithms with comparison simulations with programs MATLAB/Simulink. Found that a multi-level conversion control mechanism can control the voltage according to the objectives. In addition, SSTPC can also control the torque and speed of BLDC Motors. Therefore, this research result is a confirmation sign as satisfactory and can be further developed.

Adaptive sliding mode predictive power control of three-phase AC/DC converters

This article presents a new adaptive sliding mode–based model predictive controller for AC/DC three-phase converters achieving better dynamic performance and stability. In the classical model predictive controller available in the literature, the model-based approach, for example, proportional–integral controller is employed for producing the active power reference for the three-phase converters. The traditional proportional–integral–based model predictive controllers consist of steady-state error and slow transient response characteristics. As a result, the DC-link voltage contains uncertainties due to variations in the load demand and output voltage. To overcome these limitations, this article suggests an adaptive sliding mode controller for generating the active power reference value from the DC-link voltage which then combines with the model predictive controller in order to minimize the cost function. The proposed controller minimizes the effects of uncertainties and variations in the output voltage by adaptively regulating the gain of sliding mode controller and modifying the control law online. The cost function is then minimized using the model predictive controller in order to control the active and reactive power flow. The stability analysis of the designed controller is performed using Lyapunov theorem. The effectiveness of the designed control scheme is proved by comparing its performance with the proportional–integral model predictive controller and fixed gain sliding mode–based model predictive controller control schemes. Simulation and experimental system results are obtained for validating the presented control approach.

Index Matrices—Based Software Implementation of Power Electronic Circuit Design

This article aims to present a comprehensive approach with corresponding software that uses index matrices. They have been developed by the authors for an automated model-based design. One of the main goals of this paper is to propose a simple model solving technique for powering electronic devices (particularly, for all subsystems: power supplies, static power converters, electric filters, electrical loads, control systems, etc.). Index matrices, which contain first-order discrete dynamical system parameters, with real numbers as elements, are constructed in order so that voltages, amperages, and discrete values can be calculated. Simulations on a three-phase converter, as well as simulations on buck and boost DC-DC converters with PI controllers, are presented. The function of the proposed software (with examples on the aforementioned devices) is considered, and diagrams of its basic programming classes are shown. The latter draws electronic schemes and their respective graphics, and provides important characteristics. Simulink is used to verify results. Advantages of the proposed approach are a higher speed of calculations (compared to Simulink, due to a lack of differential equations) and a simpler handling of various electronic components. Additionally, a computational scalability is demonstrated.

A Robust Adaptive Super-Twisting Sliding Mode Controller applied on grid-tied power converter with an LCL filter

This paper presents a new robust adaptive controller, totally developed on discrete-time. This controller is composed by two control structures: a Robust Model Reference Adaptive Controller (RMRAC) and an Adaptive Super-Twisting Sliding Mode (STSM) Controller, constituting a new control structure, nominated Robust Adaptive STSM Controller. The main advantage of this new control proposal is its high adaptability and robust performance, with fast reference tracking without chattering. The stability and robustness analysis, in discrete time, are presented, considering the overall plant, that is, in presence of matched and unmatched dynamics. To evaluate its robustness performance, the proposed controller is designed for grid-injected current control of three-phase grid-tied power converter with an LCL filter under weak grid. To validate it, the plant was partially modeled as a first order transfer function, neglecting capacitor dynamics and considering it as an additive dynamics on control design. Experimental results are presented to corroborate the controller performance and the stability analysis by means of Lyapunov Theory is provided.

Analysis and Design of Three-Phase LLC Resonant Converter with Matrix Transformers

This study presents the topology of a three-phase LLC resonant converter with matrix transformers. The three-phase LLC resonant converter has the advantages of conventional LLC resonant converters, including zero-voltage switching at the primary side, zero-current switching at the secondary side, high-frequency feasibility, and high efficiency. Moreover, it has additional advantages that differ from conventional LLC, including low output capacitor current ripple, natural current sharing in three resonant currents, and a high power level. As a result of the above mentioned characteristics, LLC topology has been used in many electric vehicle charging systems, server power systems, and other high-power applications. However, as the power level becomes higher and higher, the input voltage is usually too high to reduce conduction loss, and the output current also increases. This situation makes transformer design more difficult. The increasing current means more core and copper loss, and the heat dissipation of the transformer becomes more difficult. Matrix transformer technology can improve this problem directly and simply. By utilizing matrix transformers, which are primary series connected and secondary parallel connected, the primary voltage stress and secondary current stress of the transformers can be reduced, and the output current can be distributed. The analysis of the proposed converter in this study includes a circuit operation introduction, a time-domain analysis, calculation of the transfer ratio curve in the frequency domain, and a loss analysis. The theoretical analysis and performance of the proposed converter are verified. A three-phase LLC resonant converter with matrix transformers prototype is built with a high input voltage of 800-VDC and high output current of 200-A. The output voltage is 100-VDC. The waveform and efficiency data will be shown in the experimental results.

Fault Ride-Through Capability of MMC Based Wind Power Plant Integrated Under a DC-Link Fault

This paper presents a novel fault ride-through (FRT) capability with the use of active converters (Vienna rectifier-I and five-level three-phase modular multilevel converter (MMC)) integrated with permanent magnet synchronous generator (PMSG) supplying AC load. The DC-link fault is controlled with the use of fault blocking diode and MMC sub-module (SM) based wind power plant (WPP). A 16 kW, 60 Hz, PMSG and wind turbine (WT) integrated with the machine-side converter (MSC), and grid-side converter (GSC) are utilized as wind farm components, along with direct current (DC) transmission grid. This topology contributes to the stability and reliability of the system by ensuring continuous output power under transient fault conditions. The functional response of the system is presented using power simulator (The PowerSim, Rockville, USA) software to demonstrate the performance of the proposed controller.

An EMC performance improvement method for three-phase half-bridge converter drive power supply

Analyze the electromagnetic interference (EMI) of the primary circuit of the switch tube driving power in the three-phase half-bridge converter, and study how to improve the electromagnetic compatibility (EMC) performance. The high-frequency EMI source caused by high-speed switching in the three-phase half-bridge converter is analyzed and quantitatively calculated. The high-frequency conduction model of the three-phase half-bridge converter and the driving power supply is established. Through the establishment of a high-frequency model, it is pointed out that EMI sources cause three interference conduction paths to the driving power supply: conduction paths I and II between the primary circuit and the driving power supply, conduction paths III between the driving power supply, and use the high-frequency model to obtain three conduction paths Based on the equivalent high-frequency circuit of the channel and the corresponding transfer function, a general method for suppressing three kinds of interference and improving the EMC performance of the drive power is proposed based on the transfer function. The experimental results show that the interference between the driving power supplies is the direct interference. The interference can be significantly reduced by paralleling the capacitors in the ambitious power load.

A Multiple Open-Circuit Fault Diagnosis Method for Two-Level Three-Phase Voltage Source Converters Based on Average-Phase Voltage Model

This article presents a fault diagnosis method in the two-level three-phase voltage source converter (VSC) systems based on the average-phase voltage (APV) model without additional sensors or hardware circuits, which can diagnose and locate multiple open-circuit (OC) faults correctly and quickly. First, based on the idea of APV within one switching period and the changing rules of basic voltage vector after OC faults, the APV model consisting of grid-side APV (GAPV) model, prefault converter-side APV (CAPV) model, and postfault CAPV model is proposed. The APV model can be used to estimate the phase voltage under different OC faults. And then, the residual feature between GAPV and CAPV is analyzed under different single or multiple OC faults. With the help of the proposed APV model, both single and multiple OC faults can be diagnosed by deviation polarity, which avoids the complex deviation polarity sequences judgment. Meanwhile, the fault diagnosis method has the ability of correctness verification, which can strengthen the robustness and prevent false alarms. Finally, the effectiveness of the proposed model and method is validated with experiments; the multiple OC faults can be located within 2.5 ms.

Performance Analysis of Modular Multilevel Converter with NPC Sub-Modules in Photovoltaic Grid-Integration

In this article, a three-phase modular multilevel converter (MMC) with three-level neutral point clamped converter (NPC) sub-modules (SMs) along with the placement of transformers in place of arm inductors is proposed for PV grid integration. Compared to the traditional MMCs, the proposed configuration reduces the voltage and power rating for the switches and the requirement of a high capacitor bank. In order to analyze the performance of the proposed converter arrangement, we have implemented four pulse width modulation schemes, such as Sine PWM with phase-level shifted carrier (SPWMLSC), Sine PWM with a phase-shifted carrier (SPWMPSC), Sine with the third harmonic injected level-shifted carrier (STHILSC), and Sine with the third harmonic injected phase-shifted carrier (STHIPSC). The proposed converter was simulated in the MATLAB/Simulink platform. Under normal and faulty operation, the results were presented with their performance indices of voltage and current harmonic distortion and sub-module capacitor voltage ripples at various modulation indices.

Real-Time Simulation Modeling Method of Multiphase Converters Based on High-Order Approximation in Micro-grid

As more and more distributed energy resources accessing in a micro-grid, the electromagnetic transient simulation of the whole system becomes extremely complicated due to the increase of multiphase converters. The traditional real-time simulation models of multiphase converters are low in efficiency for their large number of electronic switches and power system nodes. To solve this problem, an efficient real-time simulation modeling method based on high-order approximation is proposed. Starting with the symmetry of structure, the twelve-phase converter and induction motor are equivalent to a three-phase converter and induction motor and thus reducing the order of the model. The switching function model of the three-phase converter is derived, and the mathematical expressions of switching functions are calculated by high-order approximation expansion of the Fourier series; then, the dc input current of the three-phase converter is formulated theoretically. Counteracting the harmonics by means of phase-shifting, the high-order approximation model of the twelve-phase converter is constructed. Finally, the real-time simulation platform and experimental platform of the twelve-phase frequency converter and induction motor are built; the simulation results verify the high efficiency and accuracy of the proposed real-time simulation model compared with traditional models of the multiphase frequency converter.

Research on diagnosis method of series arc fault of three-phase load based on SSA-ELM

Arc fault in the three-phase load circuit may cause fire, resulting in production interruption and even worse, it will cause casualties. In order to effectively detect the arc fault in the three-phase circuit, series arc fault experiments of three-phase motor load and frequency converter were carried out under different current conditions. Firstly, variational mode decomposition (VMD) was performed for each cycle of A-phase current, and then the VMD energy entropy and sample entropy were calculated. Secondly, the noise-dominated component was removed according to the permutation entropy, then the average value after first-order difference of the half-cycle reconstructed signal was obtained. An arc fault diagnosis model of extreme learning machine (ELM) optimized by sparrow search algorithm (SSA) was established. The feature vectors were divided into training group and test group to train the model and test its fault diagnosis accuracy. Compared with GA-ELM, PSO-ELM, support vector machine (SVM) and SSA-SVM, the experimental results show that the proposed method can identify the series arc fault accurately and more quickly.

A Review of Three Phase AC-DC Power Factor Correction Converters for Electric Vehicle Fast Charging

Electric vehicle charging station for fast DC charging performs AC-DC conversion at off-board. In recent years, three-phase AC-DC power factor correction (PFC) converters are dealt with fast charger. These converters are developed using unidirectional and bidirectional power flow structure. In this study, three-phase AC-DC PFC converter topologies, providing bidirectional power flow, are evaluated in terms of performance. The aim is to present the latest technology of bidirectional multilevel AC-DC PFC converters for EV fast charging. This paper provides a comprehensive and practical review for researchers interested in fast charging infrastructure for electric vehicles.

Control of a Three-Phase Power Converter Connected to Unbalanced Power Grid in a Non-Cartesian Oblique Frame

The article presents a new approach to positive and negative sequence current vector control of a grid-connected three-phase three-wire power electronic converter operating under grid voltage imbalance conditions. The concept utilizes the representation of unbalanced converter current in the new coordinates frame in which the current vector components are constant. The nonlinear trigonometric transformation of two-dimensional current vector components from the stationary frame to the new frame is found online depending on the reference current asymmetry. The presented concept of new coordinates utilization allows implementation of proportional-integral terms as current regulators without the use of resonant terms and without the use of the measured current symmetrical sequences decomposition. The article presents the theoretical approach, simulation results, as well as laboratory tests results.

Cophase Traction Power Supply System Based-MMC-Vv Wiring

A new homogeneous traction power supply scheme based on Vv wiring transformers and modular multilevel converters (MMC) is proposed, which due to address the electrical power quality problems and the negative effects of power splitting on locomotives in electrified railways. The three-phase converter in this paper adopts MMC-based active power compensator (APC), which can eliminate the bridge arm of one phase converter and the step-down isolation transformer compared with the conventional single-phase back-to-back structure converter. The compensation relationship of each port of APC is derived, and the dynamic compensation control strategy of APC is established, and the equalization control and phase shifting carrier techniques are applied to control them and achieve the compensation target. Finally, MATLAB/Simulink is employed as a platform to build a model for simulation, and the experimental results verify the feasibility of the compensation strategy.

New Powertrain Configurations Based on Six-Phase Current-Source Inverters for Heavy-Duty Electric Vehicles

In this paper, new powertrain configurations for heavy-duty electric vehicles (HDEV) are proposed based on current-source inverters (CSI) and asymmetrical six-phase motors. Voltage-source inverters (VSI) are widespread in many applications; however, VSI-based powertrains require a bulky bank of capacitors with a limited lifetime. Recently, powertrains based on the current-source inverter (CSI) are getting more attention to be a more reliable structure for EVs by replacing the dc-link capacitor with a choke inductor. To the authors&#x2019; best knowledge, a six-phase CSI-based powertrain is not fully addressed yet. Since the six-phase CSI comprises two three-phase CSIs, multiple configurations can arise based on the connection between the two CSIs. In this context, the proposed powertrain configurations are based on parallel, cascaded, and standalone six-phase CSIs. The standalone topology is based on separating the two three-phase converters by supplying each converter with a dedicated dc-dc converter. All the proposed configurations are studied from the perspective of structure, modulation, and stresses/sizing. A case study highlights the differences and compares the three structures. The comparison is backed by experimental results, and a detailed discussion is provided for concluding a suggested selection of the best-suited topology.

Direct Current Motor Position Control by a Sliding Mode Controlled Dual Three-Phase AC-DC Power Converter

Direct voltage source (DC) and a DC/DC power converter can be used to control the position, speed or torque of a DC motor. In such an operational condition, a rectifier is needed to have a DC voltage source, if a three-phase voltage source is available only. The objective of this study is to replace a rectifier and DC/DC power converter with one AC/DC power converter such that its output would be equal to the voltage needed for control of DC motor. It is assumed that the control algorithm of a DC motor is selected, which means that the desired output voltage of the AC/DC converter as a time function or function of the motor state is known. First, the sliding mode methodology is applied to control the converter's three branches to make three-phase input current track source voltages multiplied by a time-varying gain. Then the gain is selected such that the converter output voltage is equal to the desired input of the DC motor. It is shown that this condition holds if the time-varying gain satisfies the first-order differential equation, which can be implemented as part of the controller. The application of the Lyapunov theory confirmed that the position regulation process has a stable equilibrium point at the origin and the time gain variation is bounded. The power efficiency is equal to one which is a desirable setting in the proposed controller. A numerical simulation demonstrates the application of the developed control methodology for both constant and time-varying angular position reference.