Research

12 pages, 3199 KiB

Open AccessArticle

Assessment of a Universal Reconfiguration-less Control Approach in Open-Phase Fault Operation for Multiphase Drives

by Federico Barrero, Mario Bermudez, Mario J. Duran, Pedro Salas and Ignacio Gonzalez-Prieto

Energies 2019, 12(24), 4698; https://doi.org/10.3390/en12244698 - 10 Dec 2019

Cited by 14 | Viewed by 2178

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Different nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control [...] Read more.

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Different nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control (MPC), have been used in recent times to govern these complex systems, including mandatory control reconfiguration to guarantee the fault tolerance characteristic. A new reconfiguration-less approach based on virtual voltage vectors (VVs) was recently proposed for MPC, providing a natural healthy and faulty closed-loop regulation of a particular asymmetrical six-phase drive. This work validates the interest in the reconfiguration-less approach for direct controllers and multiphase drives. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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19 pages, 6857 KiB

Open AccessArticle

Prediction of PWM-Induced Current Ripple in Subdivided Stator Windings Using Admittance Analysis

by Antoine Cizeron, Javier Ojeda, Eric Labouré and Olivier Béthoux

Energies 2019, 12(23), 4418; https://doi.org/10.3390/en12234418 - 21 Nov 2019

Cited by 2 | Viewed by 2197

Abstract

Subdividing stator winding is a way to lower the DC link voltage value in electric drives and reduce the stress on motor insulation. Coupled windings sharing the same stator teeth are modelled in order to evaluate the link between voltages disparities and current [...] Read more.

Subdividing stator winding is a way to lower the DC link voltage value in electric drives and reduce the stress on motor insulation. Coupled windings sharing the same stator teeth are modelled in order to evaluate the link between voltages disparities and current ripple. This paper provides an assessment of current ripple rise in the subdivided windings compared to ordinary topologies through the use of a basic inductive model. A method for PWM-Induced current ripple and high-frequency loss estimation based on admittance measurements is developed and experimentally validated. The use of this subdivided structure does not induce more than a 10% rise of the PWM-induced current ripple compared to a standard winding structure. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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16 pages, 8013 KiB

Open AccessArticle

Efficient Model Predictive Control with Natural Fault-Tolerance in Asymmetrical Six-Phase Induction Machines

by Angel Gonzalez-Prieto, Ignacio Gonzalez-Prieto, Mario J. Duran and Federico Barrero

Energies 2019, 12(20), 3989; https://doi.org/10.3390/en12203989 - 20 Oct 2019

Cited by 10 | Viewed by 2072

Abstract

Multiphase machines allow enhancing the performance of wind energy conversion systems from the point of view of reliability and efficiency. The enhanced robustness has been traditionally achieved with a mandatory post-fault control reconfiguration. Nevertheless, when the regulation of x-y currents in multiphase drives [...] Read more.

Multiphase machines allow enhancing the performance of wind energy conversion systems from the point of view of reliability and efficiency. The enhanced robustness has been traditionally achieved with a mandatory post-fault control reconfiguration. Nevertheless, when the regulation of x-y currents in multiphase drives is done in open-loop mode, the reconfiguration can be avoided. As a consequence, the reliability of the system increases because fault detection errors or delays have no impact on the post-fault performance. This capability has been recently defined as natural fault tolerance. From the point of view of the efficiency, multiphase machines present a better power density than three-phase machines and lower per-phase currents for the same voltage rating. Moreover, the implementation of control strategies based on a variable flux level can further reduce the system losses. Targeting higher reliability and efficiency for multiphase wind energy conversion systems, this work proposes the implementation of an efficient model predictive control using virtual voltage vectors for six-phase induction machines. The use of virtual voltage vectors allows regulation of the x-y currents in open-loop mode and achieving the desired natural fault tolerance. Then, a higher efficiency can be achieved with a simple and universal cost function, which is valid both in pre- and post-fault situations. Experimental results confirm the viability and goodness of the proposal. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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Graphical abstract

9 pages, 557 KiB

Open AccessArticle

Min-Max Predictive Control of a Five-Phase Induction Machine

by Daniel R. Ramirez, Cristina Martin, Agnieszka Kowal G. and Manuel R. Arahal

Energies 2019, 12(19), 3713; https://doi.org/10.3390/en12193713 - 28 Sep 2019

Viewed by 1846

Abstract

In this paper, a fuzzy-logic based operator is used instead of a traditional cost function for the predictive stator current control of a five-phase induction machine (IM). The min-max operator is explored for the first time as an alternative to the traditional loss [...] Read more.

In this paper, a fuzzy-logic based operator is used instead of a traditional cost function for the predictive stator current control of a five-phase induction machine (IM). The min-max operator is explored for the first time as an alternative to the traditional loss function. With this proposal, the selection of voltage vectors does not need weighting factors that are normally used within the loss function and require a cumbersome procedure to tune. In order to cope with conflicting criteria, the proposal uses a decision function that compares predicted errors in the torque producing subspace and in the x-y subspace. Simulations and experimental results are provided, showing how the proposal compares with the traditional method of fixed tuning for predictive stator current control. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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9 pages, 498 KiB

Open AccessArticle

Constraint Satisfaction in Current Control of a Five-Phase Drive with Locally Tuned Predictive Controllers

by Agnieszka Kowal G., Manuel R. Arahal, Cristina Martin and Federico Barrero

Energies 2019, 12(14), 2715; https://doi.org/10.3390/en12142715 - 16 Jul 2019

Cited by 4 | Viewed by 1713

Abstract

The problem of control of stator currents in multi-phase induction machines has recently been tackled by direct digital model predictive control. Although these predictive controllers can directly incorporate constraints, most reported applications for stator current control of drives do no use this possibility, [...] Read more.

The problem of control of stator currents in multi-phase induction machines has recently been tackled by direct digital model predictive control. Although these predictive controllers can directly incorporate constraints, most reported applications for stator current control of drives do no use this possibility, being the usual practice tuning the controller to achieve the particular compromise solution. The proposal of this paper is to change the form of the tuning problem of predictive controllers so that constraints are explicitly taken into account. This is done by considering multiple controllers that are locally optimal. To illustrate the method, a five-phase drive is considered and the problem of minimizing

x - y

losses while simultaneously maintaining the switching frequency and current tracking error below some limits is tackled. The experiments showed that the constraint feasibility problem has, in general, no solution for standard predictive control, whereas the proposed scheme provides good tracking performance without violating constraints in switching frequency and at the same time reducing parasitic currents of

x - y

subspaces. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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14 pages, 10191 KiB

Open AccessArticle

Predictive-Fixed Switching Current Control Strategy Applied to Six-Phase Induction Machine

by Osvaldo Gonzalez, Magno Ayala, Jesus Doval-Gandoy, Jorge Rodas, Raul Gregor and Marco Rivera

Energies 2019, 12(12), 2294; https://doi.org/10.3390/en12122294 - 15 Jun 2019

Cited by 29 | Viewed by 3223

Abstract

In applications such as multiphase motor drives, classical predictive control strategies are characterized by a variable switching frequency which adds high harmonic content and ripple in the stator currents. This paper proposes a model predictive current control adding a modulation stage based on [...] Read more.

In applications such as multiphase motor drives, classical predictive control strategies are characterized by a variable switching frequency which adds high harmonic content and ripple in the stator currents. This paper proposes a model predictive current control adding a modulation stage based on a switching pattern with the aim of generating a fixed switching frequency. Hence, the proposed controller takes into account the prediction of the two adjacent active vectors and null vector in the (

α

-

β

) frame defined by space vector modulation in order to reduce the (x-y) currents according to a defined cost function at each sampling period. Both simulation and experimental tests for a six-phase induction motor drive are provided and compared to the classical predictive control to validate the feasibility of the proposed control strategy. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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12 pages, 2906 KiB

Open AccessFeature PaperArticle

Model-Based Predictive Current Controllers in Multiphase Drives Dealing with Natural Reduction of Harmonic Distortion

by Cristina Martin, Federico Barrero, Manuel R. Arahal and Mario J. Duran

Energies 2019, 12(9), 1679; https://doi.org/10.3390/en12091679 - 03 May 2019

Cited by 5 | Viewed by 2380

Abstract

An important drawback in the application of model-based predictive controllers for multiphase systems is the relatively high harmonic content. Harmonics arise due to the fixed sampling-time nature and the absence of modulation methods in the control technique. Recent research works have proposed different [...] Read more.

An important drawback in the application of model-based predictive controllers for multiphase systems is the relatively high harmonic content. Harmonics arise due to the fixed sampling-time nature and the absence of modulation methods in the control technique. Recent research works have proposed different procedures to overcome this disadvantage at the expense of increasing the complexity of the controller and, in most cases, the computational requirements. There are, however, natural ways to face this harmonic generation that have been barely explored in the scientific literature. These alternatives include the use of variable sampling times or the application of the observer theory, whose utility has been stated without excessively increasing the computational cost of the controller. This paper presents the basis of both methodologies, analyzing their interest as natural alternatives to mitigate the generation of harmonic components in modern electrical drives when using predictive controllers. A five-phase induction machine is used as a case example to experimentally validate the study and draw conclusions. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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13 pages, 1460 KiB

Open AccessArticle

A Generalised Multifrequency PWM Strategy for Dual Three-Phase Voltage Source Converters

by Jose A. Riveros, Joel Prieto, Marco Rivera, Sergio Toledo and Raúl Gregor

Energies 2019, 12(7), 1398; https://doi.org/10.3390/en12071398 - 11 Apr 2019

Cited by 9 | Viewed by 3082

Abstract

Pulse width modulation (PWM) strategies for the control of asymmetrical six-phase drives have been widely studied since the beginning of this century. Nevertheless, space vector modulation (SVM) techniques with multifrequency voltage injection for the control of all the degrees of freedom of the [...] Read more.

Pulse width modulation (PWM) strategies for the control of asymmetrical six-phase drives have been widely studied since the beginning of this century. Nevertheless, space vector modulation (SVM) techniques with multifrequency voltage injection for the control of all the degrees of freedom of the multiphase model is still a subject under research. This paper deals with this topic and introduces a generalised PWM method for a two-level voltage source converters. The architecture was derived by extending a three-phase modulator proposed as an alternative to the widely studied SVM. The proposal computes the duty times straightforwardly with a fast algorithm based on an analytical solution of the voltage-time modulation law. Theoretical derivations supported by experimental results demonstrate the proper synthesis of the multifrequency target voltage in the linear modulation region as well as good frequency behaviour of the presented modulation strategy. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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15 pages, 3184 KiB

Open AccessArticle

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

by Daniel Gutierrez-Reina, Federico Barrero, Jose Riveros, Ignacio Gonzalez-Prieto, Sergio L. Toral and Mario J. Duran

Energies 2019, 12(2), 314; https://doi.org/10.3390/en12020314 - 19 Jan 2019

Cited by 7 | Viewed by 3136

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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17 pages, 6587 KiB

Open AccessArticle

Current Control of a Six-Phase Induction Machine Drive Based on Discrete-Time Sliding Mode with Time Delay Estimation

by Yassine Kali, Magno Ayala, Jorge Rodas, Maarouf Saad, Jesus Doval-Gandoy, Raul Gregor and Khalid Benjelloun

Energies 2019, 12(1), 170; https://doi.org/10.3390/en12010170 - 05 Jan 2019

Cited by 39 | Viewed by 4572

Abstract

This paper proposes a robust nonlinear current controller that deals with the problem of the stator current control of a six-phase induction motor drive. The current control is performed by using a state-space representation of the system, explicitly considering the unmeasurable states, uncertainties [...] Read more.

This paper proposes a robust nonlinear current controller that deals with the problem of the stator current control of a six-phase induction motor drive. The current control is performed by using a state-space representation of the system, explicitly considering the unmeasurable states, uncertainties and external disturbances. To estimate these latter effectively, a time delay estimation technique is used. The proposed control architecture consists of inner and outer loops. The inner current control loop is based on a robust discrete-time sliding mode controller combined with a time delay estimation method. As said before, the objective of the time delay estimation is to reconstruct the unmeasurable states and uncertainties, while the sliding mode aims is to suppress the estimation error, to ensure robustness and finite-time convergence of the stator currents to their desired references. The outer loop is based on a proportional-integral controller to control the speed. The stability of the current closed-loop system is proven by establishing sufficient conditions on the switching gains. Experimental work has been conducted to verify the performance and the effectiveness of the proposed robust control scheme for a six-phase induction motor drive. The results obtained have shown that the proposed method allows good performances in terms of current tracking, in their corresponding planes. Full article

(This article belongs to the Special Issue Control of Multiphase Machines and Drives)

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