A Unified Analysis of the Fault Tolerance Capability in Six-Phase Induction Motor Drives
TL;DR: In this article, the authors provide a full picture of the postfault derating in generic six-phase machines and a specific analysis of the fault-tolerant capability of the three mainstream sixphase induction machines (asymmetrical, symmetrical, and dual three phase).
Abstract: The fault tolerance of electric drives is highly appreciated at industry for security and economic reasons, and the inherent redundancy of six-phase machines provides the desired fault-tolerant capability with no extra hardware. For this reason some recent research efforts have been focused on the fault-tolerant design, modeling, and control of six-phase machines. Nevertheless, a unified and conclusive analysis of the postfault capability of six-phase machine is still missing. This paper provides a full picture of the postfault derating in generic six-phase machines and a specific analysis of the fault-tolerant capability of the three mainstream six-phase induction machines (asymmetrical, symmetrical, and dual three phase). Experimental results confirm the theoretical post fault current limits and allow concluding, which is the best six-phase machine for each fault scenario and neutral arrangement.
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28 Nov 2019
TL;DR: Different topologies used in dual three-phase drives and the modulation techniques used to operate them are presented as well as the status of using MPDs in traction applications industrially and the upcoming trends toward promoting this technology more are presented.
Abstract: This article attempts to cover the most recent advancements in multiphase drives (MPDs), which are candidates for replacing three-phase drives in electric vehicle (EV) applications. Multiphase machines have distinctive features that arouse many research directions. This article reviews the recent advancements in several aspects such as topology, control, and performance to evaluate the possibility of exploiting them more in EV applications in future. The six-phase drives are extensively covered here because of their inherent structure as a dual three-phase system, which eases the production process. This article presents different topologies used in dual three-phase drives and the modulation techniques used to operate them as well as the status of using MPDs in traction applications industrially and the upcoming trends toward promoting this technology more.
149 citations
Cites background or methods from "A Unified Analysis of the Fault Tol..."
...The single-neutral point connection proves worthy in the fault-tolerant operation, whereas the two isolated neutral point connection has better dc-link utilization and simpler current controllers, because no zero-sequence currents can physically flow in this type of connection [15]....
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...A unified analysis using the same strategies, but with more than single-phase winding loss, is discussed in [15]....
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...(a) Asymmetrical and (b) symmetrical six-phase machines [15]....
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TL;DR: In this paper, fault diagnosis and fault-tolerant control strategies have been studied comprehensively for dual three-phase permanent-magnet synchronous motor (PMSM) drives to improve the reliability.
Abstract: In this paper, fault diagnosis and fault-tolerant control strategies have been studied comprehensively for dual three-phase permanent-magnet synchronous motor (PMSM) drives to improve the reliability. Based on direct torque control (DTC) with space vector modulation, a series of diagnostic and tolerant control methods have been proposed for five types of faults, namely, speed-sensor fault, dc-link voltage-sensor fault, current-sensor fault, open-phase fault, and open-switch fault. First, diagnosis and tolerant schemes are proposed for speed-sensor fault by estimating the rotor angle speed with the rotating speed of stator flux. Second, diagnosis and tolerant schemes are proposed for dc-link voltage-sensor fault by combining the current model based stator flux observer with the voltage model based stator flux observer. Third, a three-step method is designed to diagnose three types of faults related to current signals, namely, current-sensor fault, open-phase fault, and open-switch fault simultaneously. A vector space decomposition based current estimation method is proposed to achieve fault-tolerant control for the current-sensor fault, and the voltage compensation based fault-tolerant control is presented for both open-phase and open-switch faults. The experiments have been taken on a laboratory prototype to verify the effectiveness of the proposed fault diagnosis and fault-tolerant schemes.
144 citations
Cites background or methods from "A Unified Analysis of the Fault Tol..."
...achieved by using auxiliary circuit or keeping operation with remaining phases [23]–[25]....
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...In [25], the fault-tolerant phase currents of six-phase induction motor under open-phase fault are reconstructed with the cost functions of minimum loss and maximum torque, respectively....
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TL;DR: In this paper, the authors proposed new fault indices that detect and locate the open-phase faults without additional hardware, which proves to be simple and independent of the operating point, control technique, and drive parameters.
Abstract: Fault tolerance is much appreciated at industry in applications with high-reliability requirements. Due to their inherent fault-tolerant capability against open-phase faults (OPFs), drives with multiple three-phase windings are ideal candidates in such applications and for this reason many efforts have been devoted to the development of different fault-tolerant control strategies. Fault detection is, however, a previous and mandatory stage in the creation of fault-tolerant drives, and the study of specific OPF detection methods for six-phase drives is still scarce. Taking advantage of the secondary currents (so called x - y currents) that are unique in multiphase machines, this study proposes new fault indices that detect and locate the OPFs without additional hardware. The method proves to be simple and independent of the operating point, control technique, and drive parameters. Comparative experimental results confirm the capability of the proposed method to achieve fast detection times with good robustness.
100 citations
Cites methods from "A Unified Analysis of the Fault Tol..."
...The VSDFD method detects the fault in approximately 10 ms and then the x-y reference currents are properly modified according to the maximum torque mode [42], as it is shown in the Fig....
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TL;DR: Although experimental results show that MPC misbehaves after the fault occurrence, the fast detection provided by the VSD approach allows a satisfactory transition to postfault mode of operation.
Abstract: Achieving a self-reconfigurable fault-tolerant control in multiphase machines requires a fast fault detection and localization. Most fault detection techniques inherit the three-phase approach by defining fault indices in a per-phase basis. A recent approach suggests an alternative fault detection mechanism based on vector space decomposition (VSD) variables, but the study is limited to open-phase faults (OPFs) for a six-phase drive that is regulated under field-oriented control. It is known, however, that 1) the open-switch faults (OSFs) in the converter are more likely than the OPF in the machine and 2) the drive performance in the event of an open-circuit fault is more critical when model predictive control (MPC) is used. This work extends the study of the VSD fault detection method to multiphase machines with different number of phases (five), control strategy (MPC), and type of faults (OPF and OSF). Although experimental results show that MPC misbehaves after the fault occurrence, the fast detection provided by the VSD approach allows a satisfactory transition to postfault mode of operation.
96 citations
Cites methods from "A Unified Analysis of the Fault Tol..."
...The application of the VSDFD method together with any of the faulttolerant control strategies suggested in [16], [17], and [36]–[44] provides an electric drive with self-healing properties....
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TL;DR: The performances of available fault-tolerant three-phase induction motor drives have been reinvestigated, taking into account the impact of not just currents, but also voltage limits for both the inverter and machine.
Abstract: With the increasing demand for electric vehicles, reliability in motor drives is an issue of growing importance. Over the years, various fault-tolerant three-phase motor drive topologies have been introduced and their performances have been investigated. Evaluation of the postfault power of a fault-tolerant drive should take into account both the postfault torque and speed, which depend on both the postfault current and voltage limits. Nevertheless, the postfault motor voltage limits are usually omitted from discussion. Furthermore, current limit in induction motor drive is not as direct as that in permanent magnet motor drive, due to the presence of the flux current. In this paper, the performances of available fault-tolerant three-phase induction motor drives have been reinvestigated, taking into account the impact of not just currents, but also voltage limits for both the inverter and machine. By deriving the postfault machine voltage equations, the effects of machine parameters and operating point on the voltage limit and hence the speed limit are explained. Depending on the topology, the motor may be able to run above the rated speed to gain extra power. The analysis is verified through experiment results on a 1 kW induction machine for four different fault-tolerant drive topologies.
73 citations
References
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TL;DR: A detailed overview of the state-of-the-art in multiphase variable-speed motor drives can be found in this article, where the authors provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as the approaches to the design of fault tolerant strategies for post-fault drive operation.
Abstract: The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operation.
1,445 citations
TL;DR: The analysis suggests that the dual (or triple) three-phase PMAC motor drive may be a favored choice for general aerospace applications, striking a balance between necessary redundancy and undue complexity, while maintaining a balanced operation following a failure.
Abstract: This paper presents an overview of motor drive technologies used for safety-critical aerospace applications, with a particular focus placed on the choice of candidate machines and their drive topologies. Aircraft applications demand high reliability, high availability, and high power density while aiming to reduce weight, complexity, fuel consumption, operational costs, and environmental impact. New electric driven systems can meet these requirements and also provide significant technical and economic improvements over conventional mechanical, hydraulic, or pneumatic systems. Fault-tolerant motor drives can be achieved by partitioning and redundancy through the use of multichannel three-phase systems or multiple single-phase modules. Analytical methods are adopted to compare caged induction, reluctance, and PM motor technologies and their relative merits. The analysis suggests that the dual (or triple) three-phase PMAC motor drive may be a favored choice for general aerospace applications, striking a balance between necessary redundancy and undue complexity, while maintaining a balanced operation following a failure. The modular single-phase approach offers a good compromise between size and complexity but suffers from high total harmonic distortion of the supply and high torque ripple when faulted. For each specific aircraft application, a parametrical optimization of the suitable motor configuration is needed through a coupled electromagnetic and thermal analysis, and should be verified by finite-element analysis.
779 citations
"A Unified Analysis of the Fault Tol..." refers background in this paper
...Good examples can be found in multiMW wind turbines [11]–[12], high-speed elevators [13], and aircraft systems [14], equipped with multiple three-phase backto-back modules that feed a 3k-phase machine....
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...Even though the analysis of the fault tolerance in five-phase drives has drawn attention within the scientific community [8]–[10], the development of multiphase demonstrators and industrial products has been mainly restricted to machines with multiple sets of three-phase windings [11]–[14]....
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TL;DR: The main objective of the two-part survey named ‘Recent Advances in the Design, Modeling, and Control of Multiphase Machines’ is to present relevant contributions to encourage and guide new advances and developments in the field.
Abstract: The main objective of this two-part state-of-the-art paper called “Recent Advances in the Design, Modeling, and Control of Multiphase Machines” is to present latest contributions in the multiphase machines' field. The first part of this paper focuses on the recent progress in the design, modeling, and control, whereas the drive is in healthy operation. This second part presents relevant contributions in two not analyzed fields. The first is in relation with the use of the additional degrees of freedom of multiphase machines and the exploitation of their fault-tolerant capabilities without adding extra hardware. The second one analyzes multiphase generation, particularly in grid-connected wind energy conversion systems and stand-alone applications. Recent progresses are shown and open challenges and future research directions are discussed.
607 citations
TL;DR: The recent progress in two specific areas associated with multiphase systems are surveyed, namely power electronic supply control and innovative ways of using the additional degrees of freedom inMultiphase machines for various nontraditional purposes.
Abstract: Multiphase variable-speed drives and generation systems (systems with more than three phases) have become one of the mainstream research areas during the last decade. The main driving forces are the specific applications, predominantly related to the green agenda, such as electric and hybrid electric vehicles (EVs), locomotive traction, ship propulsion, “more-electric” aircraft, remote offshore wind farms for electric energy generation, and general high-power industrial applications. As a result, produced body of significant work is substantial, making it impossible to review all the major developments in a single paper. This paper therefore surveys the recent progress in two specific areas associated with multiphase systems, namely power electronic supply control and innovative ways of using the additional degrees of freedom in multiphase machines for various nontraditional purposes.
508 citations
Additional excerpts
...sign, modulation, and control issues [3]–[5]....
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