Conventional Three-phase Machines Research Articles

Development of a smart hybrid drive system with advanced logistics for railway applications

Fuel Hydrogen cells become nowadays a major candidate to replace the diesel in powering the traction locomotives since they offer low emission of pollutant gases, high efficiency, and flexible modular structure without the need for installation of electrification infrastructure for railway networks. However, they cannot respond appropriately to the fast load transients due to their slow internal electrochemical and thermodynamic responses. Therefore, they shall be integrated with fast dynamics Li-ion battery cells to form a hybrid power source for traction systems. Accordingly, this paper presents a development of a new smart integrated power source of fuel hydrogen and Li-ion battery cells to supply dual three-phase machines for driving the trains in railway networks. The developed control management system is regulating the two power sources according to the train operational modes as well as the battery state of charge. In addition to that, dual three-phase machines offer several superiorities over the conventional three-phase machines such as lower harmonic distortion and power losses along with higher power density and fault tolerance. A designated railway line is nominated through selection criteria in this paper for the implementation of the new smart drive traction system in HIL platform using Typhoon HIL real time simulator. Moreover, an optimization analysis has been carried out to reduce the overall hydrogen consumption with the same journey time spent for a designated railway line using particle swarm optimization approach. Finally, a case study is presented to illustrate a proof of concept for designing the hydrogen refueling station for such railways which are supplied by the new integrated power source of fuel hydrogen and Li-ion battery cells. The case study investigates the site selection, operational assessment, and equipment requirements.

Stator Faults Detection in Asymmetrical Six-Phase Induction Motor Drives with Single and Dual Isolated Neutral Point, Adopting a Model Predictive Controller

Multiphase drives have been presented as potential replacements for conventional three-phase machines, primarily because of their propensity to operate faultlessly. Due to the various stator phase arrangements, standard fault detection techniques are insufficiently applicable and cannot be used to diagnose faults in the various configurations of multiphase machines in closed-loop applications. The current study proposes an effective online diagnostic technique based on the computing and tracking of a significant severity factor, which is defined as the ratio of the zero, negative, and positive voltage symmetrical components employing a short-time least-square Prony algorithm (STLSP). In this study, the asymmetrical six-phase induction motor (ASPIM) was controlled by a model predictive control (MPC) algorithm, an attractive control scheme for the regulation of multiphase electric drives, since it easily exploits their inherent advantages. This article addresses stator faults in ASPIMs. The effectiveness of the suggested strategy was confirmed experimentally for various operating conditions in both steady and transient states.

A Novel Decoupling Control Scheme for Non-Salient Multi-Three-Phase Synchronous Machines Based on Multi-Stator Model

As competitive alternatives to conventional three-phase synchronous machines, synchronous multi-three-phase machines (MTPMs) are gaining increasing interests in various fields such as electrified transportation and power generation. The modular configuration is preferred for multi-three-phase drives in specific applications regarding the availability of advanced three-phase power electronics techniques and the superior capability of fault tolerance. The multi-stator (MS) modelling would be an ideal solution for the control of such modular drives as it facilitates power sharing among winding sets in a straightforward way and enables simple post fault strategies compared with the well-known vector space decomposition (VSD) modelling approach. Nevertheless, the strong magnetic coupling existing in MS model has hindered its use due to the instability and the performance deterioration issue. To solve the problem, a new decoupling control scheme directly applied in MS frame is proposed in this paper. The proposed method can deal with non-salient multi-three-phase machines whose three-phase winding sets can be identical or different, under the assumption of the sinusoidal airgap flux. Furthermore, it is shown by analysis the proposed method is characterized by significant simplicity and flexibility compared with the existing decoupling methods. The effectiveness of the proposed method has been verified through experiments including a single-side operation, a power-sharing test, and a post fault tolerant operation on a non-salient dual three-phase permanent magnet synchronous machine with quasi sinusoidal air gap flux.

Design and Performance Analysis of Axial Flux Permanent Magnet Machines with Double-Stator Dislocation Using a Combined Wye-Delta Connection

Conventional fractional slot concentrated winding three-phase axial flux permanent magnet machines have an abundance of armature reaction magnetic field harmonics which deteriorate the torque performance of the machine. This paper presents a double-stator dislocated axial flux permanent magnet machine with combined wye-delta winding. A wye-delta (Y-△) winding connection method is designed to eliminate the 6th ripple torque generated by air gap magnetic field harmonics. Then, the accurate subdomain method is adopted to acquire the no-load and armature magnetic fields of the machine, respectively, and the magnetic field harmonics and torque performance of the designed machine are analyzed. Finally, a 6kW, 4000r/min, 18-slot/16-pole axial flux permanent magnet machine is designed. The finite element simulation results show that the proposed machine can effectively eliminate the 6th ripple torque and greatly reduce the torque ripple while the average torque is essentially identical to that of the conventional three-phase machines with wye-winding connection.

Sensorless Control for Non-Sinusoidal Five-Phase Interior PMSM Based on Sliding Mode Observer

This paper proposes a sensorless control strategy based on Sliding Mode Observer (SMO) for a Five-phase Interior Permanent Magnet Synchronous Machine (FIPMSM), with a consideration of the third harmonic component. Compared to conventional three-phase machines, the third harmonic of back electromotive force (back-EMF) contains more information. Thus, in this paper, the first and third harmonic components of the five-phase machine are considered to estimate the rotor position which is necessary for the vector control. Simulation results are shown to verify the feasibility and the robustness of the proposed sensorless control strategy.

Performance Analysis of Direct Torque Controllers in Five-Phase Electrical Drives

The industrial application of electric machines has grown in the last decades, thanks to the development of microprocessors and power converters, which have permitted their use as variable-speed drives. Although three-phase machines are the common trend, the interest of the research community has recently focused on machines with more than three phases, known as multiphase machines. The principal reason lies in the exploitation of their advantages in terms of reliability, i.e., post-fault operating capability. Additionally, multiphase machines provide a better current distribution among phases, and lower current harmonic production in the power converter, than conventional three-phase machines. However, multiphase drive applications require the development of complex controllers to regulate the torque (or speed) and flux of the machine. In this regard, direct torque controllers have appeared as a viable alternative due to their easy formulation and high flexibility to incorporate control objectives. However, these controllers face some peculiarities and limitations in their use that require attention. This work aims to tackle direct torque control as a viable alternative for the regulation of multiphase drives. Special attention will be paid to the development of the control technique and the expected benefits and limitations in the obtained results. Case examples based on symmetrical five-phase induction machines with distributed windings in the motoring mode of operation will be used to this end.

Improvement of Concentrated Winding Layouts for Six-Phase Squirrel Cage Induction Motors

The fault-tolerant capability is a prerequisite for electrical safety-critical applications. In this regard, multi-phase induction motors are well-known actuators used to provide this feature. Compared to conventional three-phase machines with distributed windings, induction machines having concentrated windings could be more fault-tolerant because of increasing the number of phases. In addition, concentrated windings have shorter end-winding and less required copper weight which makes it a lower cost solution compared to distributed windings. However, concentrated windings adversely increase the distortion of the air gap flux density which affects motor performances. In this paper, a pseudo-concentrated winding layout has been proposed for six-phase squirrel-cage induction motors to improve performances compared to conventional concentrated windings. Winding function and equivalent circuit methods are used to analytically calculate performances. Finally, time-stepping finite element method and experimental measurements have been presented to confirm obtained analytical results.

A review on developments of polyphase machines

Despite machines were acquainted more than hundred, a considerable length of time ago, the innovative research work in this zone seems to be never completion. For machine drive applications, multiphase induction motor might conceivably meet the interest for high power electric drive frameworks which would both rough & vitality productive. Polyphase drives have many advantages such as reduction in the torque pulsation and increase in its frequency, reduction in power per leg of inverter, reduced volume for same output power, lower dc link current harmonic and reduced rotor copper losses. Due to these advantages the multi-phase systems are used in electric ship propulsion, locomotive traction, electric and hybrid electric vehicles, “more-electric” aircraft, and high-power industrial applications. To look into the an assortment of issues identified with the utilization of multi-phase machine as compared to the conventional three-phase machine, the research has been in progress from last few decades. Therefore this paper reviews the advance committed to multi-phase machine drive innovative work since its origin. Apart from this, Modelling, PWM schemes and its areas of applications are also discussed.

Modulation Effects in an Inverter Fed Nine-Phase Induction Motor Drive

Using electric motors with a number of phases greater than three present some advantages over conventional three-phase machines: higher reliability, reduced power per phase, increased torque density, and reduced torque pulsations. As the number of phases increases, the complexity of the modulation also increases due to a larger number of switching vectors and harmonic planes. A nine-phase inverter implies 512 switching vectors in each one of its four harmonic planes. In this article, a modulation technique for a nine-phase inverter based on a subset of the voltage vectors that yields a reduced number of on/off transitions in a switching period is shown. The resulting harmonics and their effects in multiphase machines are analyzed. Third harmonic injection is considered from the perspective of both torque improvement and dc bus voltage utilization. Simulation, finite element, and experimental results are presented to support the authors’ conclusions.

Interest and Applicability of Meta-Heuristic Algorithms in the Electrical Parameter Identification of Multiphase Machines

Multiphase machines are complex multi-variable electro-mechanical systems that are receiving special attention from industry due to their better fault tolerance and power-per-phase splitting characteristics compared with conventional three-phase machines. Their utility and interest are restricted to the definition of high-performance controllers, which strongly depends on the knowledge of the electrical parameters used in the multiphase machine model. This work presents the proof-of-concept of a new method based on particle swarm optimization and standstill time-domain tests. This proposed method is tested to estimate the electrical parameters of a five-phase induction machine. A reduction of the estimation error higher than 2.5% is obtained compared with gradient-based approaches.

New Fault-Tolerant Control Strategy of Five-Phase Induction Motor with Four-Phase and Three-Phase Modes of Operation

The developed torque with minimum oscillations is one of the difficulties faced when designing drive systems. High ripple torque contents result in fluctuations and acoustic noise that impact the life of a drive system. A multiphase machine can offer a better alternative to a conventional three-phase machine in faulty situations by reducing the number of interruptions in industrial operation. This paper proposes a unique fault-tolerant control strategy for a five-phase induction motor. The paper considers a variable-voltage, variable-frequency control five-phase induction motor in one- and two-phase open circuit faults. The four-phase and three-phase operation modes for these faults are utilized with a modified voltage reference signal. The suggested remedial strategy is the method for compensating a faulty open phase of the machine through a modified reference signal. A modified voltage reference signal can be efficiently executed by a carrier-based pulse width modulation (PWM) system. A test bench for the execution of the fault-tolerant control strategy of the motor drive system is presented in detail along with the experimental results.

Stability and performance of current harmonic controllers for multiphase PMSMs

Multiphase electric machines can provide significant benefits over conventional three-phase machines. A drawback to multiphase machines is that they are known to have problems with stator current harmonics. The harmonics can be eliminated by various current harmonic control methods. However, there appears to be no clear agreement on the most suitable method for multiphase machines. This paper aims to compare different current harmonic controllers in terms of stability and performance under model uncertainty. A detailed theoretical analysis of the harmonic controllers is given by taking a modern multi-input multi-output approach based on a structured singular value analysis. Further, the performance of the harmonic controllers is studied with experimental results from a dual three-phase permanent magnet synchronous machine. The analysis and results of this paper show how to design robust high-performance current harmonic controllers for multiphase machines.

Wide Air-gap Control for Multi-module Permanent Magnet Linear Synchronous Motors without Magnetic Levitation Windings

This paper proposes a wide air-gap control method for the multi-module permanent magnet linear synchronous motor (MM-PMLSM) based on independent vector control. In particular, the MM-PMLSM consists of symmetrical multi-module and multi-phase structures, which are basically three-phase configurations without a neutral point, unlike conventional three-phase machines. In addition, there are no additional magnetic levitation windings to control the normal force of the air-gap between each stator and mover. Hence, in this paper, a dq-axis current control applying a d-q transformation and an independent vector control are proposed for the air-gap control between the two symmetric stators and mover of the MM-PMLSM. The characteristics and control performance of the MM-PMLSM are analyzed under the concept of vector control. As a result, the proposed method is easily implemented without additional windings to control the air-gap and the mover position. The effectiveness of the proposed independent vector control algorithm is verified through experimental results.

Online Adaptation of Rotor Resistance based on Sliding Mode Observer with Backstepping Control of A Five-Phase Induction Motor Drives

Multiphase electric drives have been developed due to numerous advantages offered by those machines when it compared with the conventional three-phase machines. Multiphase motor drives are considered for applications, where the reduction of power per phase for both motor and inverter and high reliability are required. High performance control techniques are developed for multi-phase drives. The performances of the high performance controller and flux observers may be degraded during the operation. Since the parameters of Induction Motor (IM) varies continuously due to temperature variation and heating. Thus it is significantly important that the value of rotor resistance is continuously observed online and adapted by the control algorithm in order to avoid detuning effects. The efficiency and performance of an induction motor drive system can be improved by online observation of the critical parameters, such as the rotor resistance and stator resistance. Among the parameters of IM, rotor resistance is a decisive one for flux estimation, and also the stator resistance becomes critical in the low-speed operation condition. This paper presents a new online estimation method for the rotor resistance of the IM for sliding mode observer. This method generally based on theories of variable structure and is useful in order to adjust online unknown parameters (load torque and rotor resistance). The presented non-linear compensator afford a voltage inputs on the articulation of stator current and rotor speed measurements, and engender an estimates for the unknown parameters simultaneously, the non-measurable state variables (rotor flux and derivatives of the stator current and voltage) that converge to the corresponding true values. Under the persistent excitation condition, the proposed method estimates the actual value of rotor resistance, which guarantees the exact estimation of the rotor flux. Non-linear Backstepping control and adaptive sliding mode observer of a five-phase induction motor drive is presented. The accuracy and validity of the method is verified by MATLAB simulation model.

Inverse-Based Current Harmonic Controller for Multiphase PMSMs

Multiphase electric machines can provide significant advantages over conventional three-phase machines. Unfortunately, multiphase machines also have a notable disadvantage that even a small voltage excitation of certain frequency components can cause large stator current harmonics. This paper presents an inverse-based current harmonic controller to eliminate the current harmonics. A detailed theoretical analysis of the proposed harmonic controller is given including a comprehensive set of analytical design principles. The robustness of the method is studied with a multi-input multi-output approach based on a structured singular value and H∞ norm analyses. In addition to the theoretical work, the performance of the harmonic controller is investigated with experimental results from a dual three-phase permanent magnet synchronous machine (PMSM). The analysis and results of this paper show that the inverse-based current harmonic controller provides a robust and high-performance method to eliminate the current harmonics in multiphase PMSMs.

Fractional Slot Concentrated Windings: A New Method to Manage the Mutual Inductance between Phases in Three-Phase Electrical Machines and Multi-Star Electrical Machines

Mutual inductance is a phenomenon caused by the circulation of the magnetic flux in the core of an electrical machine. It is the result of the effect of the current flowing in one phase on the other phases. In conventional three-phase machines, such an effect has no influence on the electrical behaviour of the device. Although these machines are powered by power inverters, no problem should occur. The result is not the same for multi-star machines. If these machines are using a conventional winding structure, namely distributed windings, and are powered by voltage source converters, current ripples appear in the power supply lines. These current ripples are related to magnetic couplings between the stars. Designers should check these current ripples in order to stay within the limits imposed by the specifications. These electric current disturbances also provide torque ripples. With concentrated windings, a new degree of freedom appears; the configuration—number of slots/number of poles—can have a positive impact. The circulation of the magnetic flux is the initial phenomenon that produces the mutual inductance. The main goal of this discussion is to describe a design method that is able to produce not only a machine with low mutual inductance between phases, but also a multi-star machine where the stars and the phases are magnetically decoupled or less coupled. This discussion only takes into account the machines that use permanent magnets mounted on the rotor surface. This article is part of a study aimed at designing a high efficiency generator using fractional-slot concentrated-windings (FSCW).

IJIREEICE - Electrical, Electronics, Instrumentation and Control

In this paper a fuzzy logic scheme is applied for direct torque fuzzy control (DTFC) of five phase induction machine (FPIM). The proposed DTFC based on fuzzy logic technique switching table is described and compared with conventional direct torque control (DTC). The proposed fuzzy control strategy is simulated using Matlab/Simulink software. The simulation results show that DTFC method reduces torque ripple and stator flux variation and improves dynamic response. High Phase Order (HPO) multiphase motor a type of AC motor that has been developed in the last decade and due to its advantage over the three phase motor, many scientists and researchers focus on it. Each electrical motor that have over three phase stator winding can be in HPO class. Researcher demonstrated that HPO drive motor many advantage over conventional three phase motor drives. Multiphase Motor drives are mostly proposed for high power application such as traction and hybrid vehicles aircraft and etc. The advantage of multiphase machines, with respect to conventional three-phase machines are reduced torque pulsations, reduced dc-link harmonics, higher torque density, greater fault tolerant, improvement of the drive noise characteristic, reduction in the required rating per inverter leg and achieving a high power motor

Decoupled Vector Control Scheme for Dual Three-Phase Permanent Magnet Synchronous Machines

Dual three-phase electric machines have many advantages compared with conventional three-phase machines. However, the properties of such machines present challenges for current control that make it difficult to produce sufficient performance for the electric drive. This paper introduces an improved vector control scheme for dual three-phase permanent magnet synchronous machines. The study includes detailed solutions for key parts of the control such as reference frame transformations, decoupling of the current control loops, and modulation. The performance of the suggested control scheme is evaluated using finite-element analyses and experimental results. The results show that the scheme can produce desired dynamics for the current control and guarantees balanced current sharing between the winding sets. In addition, the proposed solution is capable of reducing current harmonics produced by the internal structure of the machine. This problem is, however, only partly solved since complete elimination of harmonic components is not achieved. Nevertheless, the suggested control scheme overcomes many of the disadvantages found with other control solutions. Improved control performance allows the full benefits of dual three-phase drives to be utilized even in demanding applications.

Automatic speed control of an asymmetrical six-phase induction motor using emotional controller (BELBIC)

An induction motor IM with two sets of three-phase windings in stator is called a six-phase IM SPIM. SPIM has lower torque pulsation compared to a three-phase IM and using SPIM, the power rating of inverter legs can be reduced. This paper offers a high performance intelligent controller for speed automatic control of a SPIM. A brain emotional learning based intelligent controller BELBIC is proposed as the speed controller. This emotional controller has simple structure with high auto learning feature and it is independent of parameters variations. A direct vector control in rotor flux frame based on space vector pulse width modulation SVPWM is used to decouple flux and torque control of the SPIM like a conventional three-phase machine. In this work, the d-axis current and speed reference signals are accurately tracked. An overview of the BELBIC is provided. A comparison with the conventional PI controller and Sliding Mode Control SLMC points out the superiority of the proposed BELBIC in speed response and torque ripple. Experimental results indicate that the BELBIC achieves a good speed regulation with a less control effort and torque ripple.

Direct Torque Control for Double Star Induction Motor

This paper describes a direct torque control (DTC) of dual star induction motor (DSIM). This machine possesses several advantages over conventional three-phase machine and is also known as the six-phase induction machine. The research has been underway for the last two decades to investigate the various issues related to the use of six-phase machine as a potential alternative to the conventional three-phase machine. Though six-phase machines have existed for some time, in the literature very few papers discuss DTC for six-phase motors. Therefore, in this work an investigation is reserved to the application of this type of control to the DSIM. The DTC uses the instantaneous values of voltage vector where each reference voltage vector is computed with a simple DTC algorithm. Finally, simulations results obtained from MatLab/Simulink are presented followed by a discussion.