Fault-tolerant Operation Research Articles

A Multi-Phase Brushless Direct Current Motor Design and Its Implementation in Medium-Altitude Long-Endurance Unmanned Aerial Vehicles

Nowadays, electric propulsion system implementation in vehicles is popular, and many studies and prototypes have been accomplished in this field. Aircraft are important members of the vehicle family, and Unmanned Aerial Vehicles (UAVs) are part of this family as well. Some UAVs still have conventional propulsion systems, which are less efficient and are harmful to the environment. In addition, conventional systems are vulnerable to faults in their propulsion system components. To overcome these problems, we designed a multi-phase Brushless Direct Current (BLDC) motor, to achieve fault-tolerant operation. Our designed BLDC motor was implemented in a UAV model that was created on MATLAB Simulink, based on a currently used UAV. Our design and performance analysis are shown for the BLDC motor, both standalone and as implemented in the created UAV model. The electric propulsion system performance is shown, according to the determined flight profile. We observed that the designed electric machine is capable of producing the required torque to create thrust for lifting the UAV. There are some advantages and disadvantages to using the designed electric machine in this class of UAV. This is shown in the related sections.

Fault–Tolerant Operation of Switched Reluctance Motor Using Cascaded Current and PWM Control With Effect of Commutation Angle Variation

Fault–Tolerant Operation of Switched Reluctance Motor Using Cascaded Current and PWM Control With Effect of Commutation Angle Variation

General Fault-Tolerant Operation of Electric-Drive-Reconstructed Onboard Charger Incorporating Asymmetrical Six-Phase Drive for EVs

In this paper, the fault-tolerant operation of an electric-drive-reconstructed onboard charger (EDROC) designed on the basis of an asymmetrical six-phase permanent magnet synchronous machine (ASPMSM) drive is studied and discussed for cases where an open-phase fault (OPF) occurs in any phase. The fault-tolerant operation is realized by rearranging the stator currents, aiming to eliminate the rotating field caused by the OPFs and to ensure the balance of grid currents. Each faulty case is discussed, and the rearranging scheme of stator currents is deduced. Meanwhile, a controller shared for both healthy and faulty cases is designed. Finally, some experiments are conducted to verify the theoretical analyses.

Comparative analysis of submodules and design of seventeen-level modular multilevel converter using a five-level submodule block

Abstract Multilevel inverters and various modulation techniques have been proven to be the best solutions to overcome all the limitations of conventional two- or three-level voltage source inverters. In recent years, among all topologies, modular multilevel converter (MMC) has advantages like low total harmonic distortion (THD), reduced filter requirement, fault-tolerant operation, scalability, modularity, transformerless operation, etc. The main application of MMC is found in high-voltage DC transmission (HVDC). This study describes and analyses the performance of two distinct MMC submodule (SM) topologies: the Half Bridge submodule (HBSM) and the Full Bridge submodule (FBSM). Switching pattern is simpler in HBSM topology but it has the disadvantage that it does not have DC fault current blocking capability. Whereas FBSM not only inherently can block the DC fault current but also has advantages like reduced volume of MMC and better performance. Further, having the capability to produce three voltage levels, it can be operated in boost mode. Also, by using a proper switching pattern, MMC can be designed to generate a various number of output levels by using the same five-level submodule block. Out of which 17 level MMC gives the best output. The MATLAB-Simulink model is used to simulate the circuit, and the findings are confirmed for a 17-level output voltage.

Active fault‐tolerant control of multi‐unmanned aerial vehicle system with time‐varying topology

AbstractThis paper studies an active fault‐tolerant control problem for multi‐UAV (unmanned aerial vehicle) system with time‐varying topology subject to actuator failures. A polytopic model is used to construct the time‐varying topological structure. Based on the quantitative estimation method of actuator faults' upper limit, an adaptive fault‐tolerant tracking control strategy is established by an active adjusting control parameters to compensate for unknown actuator faults, so as to obtain consensus tracking under time‐varying topology. Furthermore, the comparison simulations with the traditional control algorithm are given to demonstrate the effectiveness of the obtained results. The tracking control strategy in this paper has better fault tolerance performance with short tracking time and superior robustness.

Fault-Tolerant Performance Analysis of a Modified Neutral-Point-Clamped Asymmetric Half-Bridge Converter for an In-Wheel Switched Reluctance Motor

Reliability is an essential factor for the operation of the Switched Reluctance Motor (SRM) drive. Electric vehicles operate in harsh environments, which may degrade the operation of power converters. These failure modes include transistor open- and short-circuits, freewheeling diode open- and short-circuits, and DC-link capacitor failures. This work presents a performance analysis of an in-wheel SRM for an electric vehicle under short-circuit (SC) and open-circuit (OC) faults of a modified Neutral-Point-Clamped Asymmetric Half-Bridge (NPC-AHB) Converter. The SRM is modeled as an in-wheel electric vehicle. A separate vehicle model attached to the motor is also developed for validation and performance of the NPC-AHB under different faulty scenarios. The performance of the modified NPC-AHB is also compared with that of a conventional AHB under faulty conditions for an in-wheel 8/6 SRM. The performance indicators such as torque, speed, current, and flux are presented from MATLAB/Simulink 2023b numerical simulations.

Online DMD-based Kalman filter for current sensor fault-tolerant control of MMC-HVDC transmission systems

With the growing application of modular multilevel converter based high-voltage direct current transmission (MMC-HVDC), the sensor fault-tolerant capability in modular multilevel converters has become critical. This paper aims to boost the sensor fault-tolerant performance of the MMC-HVDC systems using advanced data-driven techniques. A novel online dynamic mode decomposition based Kalman filter (ODMDKF) is designed for fault detection and control reconfiguration. Besides, a modified dual-check fault detection module based on local outlier factor algorithm is proposed to reduce false alarm rate. Simulation studies are conducted on a modified IEEE 9-bus system with MMC-HVDC transmission lines. The results indicate that the proposed sensor fault-tolerant control method can ensure the continuous operation of the MMC-HVDC systems under the condition of three types of current sensor faults and its fault-tolerant capability is better than that of extended Kalman filter-based fault-tolerant control method.

Unified Fault-Tolerant Control and Adaptive Velocity Planning for 4WID-4WIS Vehicles under Multi-Fault Scenarios

Four-wheel independent drive and four-wheel independent steering (4WID-4WIS) vehicles provide increased redundancy in fault-tolerant control (FTC) schemes, enhancing heterogeneous fault-tolerant capabilities. This paper addresses the challenge of maintaining vehicle safety and maneuverability in the presence of actuator faults in autonomous vehicles, focusing on 4WID-4WIS systems. A novel unified hierarchical active FTC strategy is proposed to handle various actuator failures. The strategy includes an upper-layer motion controller that determines resultant force requirements based on trajectory tracking errors and a middle-layer allocation system that redistributes tire forces to fault-free actuators using fault information. This study, for the first time, considers multi-fault scenarios involving longitudinal and lateral coupling, calculating FTC boundaries for each fault type. Additionally, a fault tolerance index is introduced for 256 fault scenarios, using singular value decomposition to linearly represent the vehicle attainable force domain. Based on this, an adaptive velocity planning strategy is developed to balance safety and maneuverability under fault conditions. Matlab 2021a/Simulink and Carsim 2019 co-simulation results validate the proposed strategies, demonstrating significant improvements in fault-tolerant performance, particularly in complex and emergency scenarios.

Design and Analysis of a Highly Reliable Permanent Magnet Synchronous Machine for Flywheel Energy Storage

This article aims to propose a highly reliable permanent magnet synchronous machine (PMSM) for flywheel energy-storage systems. Flywheel energy-storage systems are large-capacity energy storage technologies suitable for the short-term storage of electrical energy. PMSMs have been used in the flywheel energy-storage systems due to their advantages. One of the key requirements for PMSMs in flywheel energy-storage systems is high reliability. A double redundant winding structure is adopted to ensure fault-tolerant operation of the PMSM. The stator is designed with auxiliary teeth to reduce the short-circuit current. Moreover, the number of slots and poles is determined to ensure the winding factor, heat dissipation, and reduce losses. Moreover, the dual three-phase stator winding structure and auxiliary teeth are adopted on the PMSM to improve reliability. Afterward, the electromagnetic performance is analyzed, and the mechanical stress is investigated to ensure mechanical strength. Finally, a prototype is built and tested to verify the theoretical analysis and performance of the PMSM.

High fault-tolerant performance of the divide-and-swap cube network

Two crucial metrics used to evaluate the fault tolerance of interconnection networks are connectivity and diagnosability. By improving the connectivity and diagnosability of the interconnection network, its fault tolerance can be enhanced. In this paper, we focus on determining the g-extra connectivity (0≤g≤10) of the divide-and-swap cube DSCn, as well as its diagnosability based on the pessimistic diagnosis strategy and g-extra precise diagnosis strategy, under the PMC and MM* models. The research analysis suggests that compared with some other connectivity and diagnosability of DSCn, such as classical connectivity, structure connectivity, super connectivity, and classical diagnosability, the extra connectivity/diagnosability and pessimistic diagnosability of DSCn enable it to have a higher fault tolerance. Moreover, we propose two O(Nlog2⁡N) effective diagnosis algorithms of DSCn: the g-extra diagnosis algorithm (EX-DiagnosisDSCn) and the pessimistic diagnosis algorithm (PE-DiagnosisDSCn), where the EX-DiagnosisDSCn algorithm can accurately diagnose the state of all processors in DSCn.

Fault-Tolerant Operation of Six-Phase Permanent Magnet Motor Drive With Open-Circuit Failures

Fault-Tolerant Operation of Six-Phase Permanent Magnet Motor Drive With Open-Circuit Failures

Fault-Tolerant Operation of Bosonic Qubits with Discrete-Variable Ancillae

Fault-tolerant quantum computation with bosonic qubits often necessitates the use of noisy discrete-variable ancillae. In this work, we establish a comprehensive and practical fault-tolerance framework for such a hybrid system and synthesize it with fault-tolerant protocols by combining bosonic quantum error correction (QEC) and advanced quantum control techniques. We introduce essential building blocks of error-corrected gadgets by leveraging ancilla-assisted bosonic operations using a generalized variant of path-independent quantum control. Using these building blocks, we construct a universal set of error-corrected gadgets that tolerate a single-photon loss and an arbitrary ancilla fault for four-legged cat qubits. Notably, our construction requires only dispersive coupling between bosonic modes and ancillae, as well as beam-splitter coupling between bosonic modes, both of which have been experimentally demonstrated with strong strengths and high accuracy. Moreover, each error-corrected bosonic qubit is comprised of only a single bosonic mode and a three-level ancilla, featuring the hardware efficiency of bosonic QEC in the full fault-tolerant setting. We numerically demonstrate the feasibility of our schemes using current experimental parameters in the circuit-QED platform. Finally, we present a hardware-efficient architecture for fault-tolerant quantum computing by concatenating the four-legged cat qubits with an outer qubit code utilizing only beam-splitter couplings. Our estimates suggest that the overall noise threshold can be reached using existing hardware. These developed fault-tolerant schemes extend beyond their applicability to four-legged cat qubits and can be adapted for other rotation-symmetrical codes, offering a promising avenue toward scalable and robust quantum computation with bosonic qubits. Published by the American Physical Society 2024

Neural adaptive performance guaranteed formation control for USVs with event-triggered quantized inputs

ABSTRACT This study presents an adaptive fault-tolerant performance guaranteed formation control strategy with event-triggered quantised inputs (EDQI) for unmanned surface vessels (USVs) in the presence of model uncertainties and actuator faults. Firstly, a prescribed performance formation guidance control law is proposed to allow formation tracking errors to evolve within the performance envelope and convergence to prescribed steady regions at an appointed time. Then, minimal-parameter-learning-based neural networks (MLP-NN) are used to tackle model uncertainties. To reduce the frequency of actuator updates and the communication burden on the channel, a dynamic memory event-triggered quantised input strategy is investigated. In addition, adaptive estimators and auxiliary design signals are built to compensate for the effects caused by input quantisation and actuator faults. It is proved that all closed-loop signals are bounded and formation errors can converge to the prescribed region at an appointed time. Finally, the effectiveness of the proposed controllers is verified by numerical simulations.

Fault-tolerant one-bit addition with the smallest interesting color code.

Fault-tolerant operations based on stabilizer codes are the state of the art in suppressing error rates in quantum computations. Most such codes do not permit a straightforward implementation of non-Clifford logical operations, which are necessary to define a universal gate set. As a result, implementations of these operations must use either error-correcting codes with more complicated error correction procedures or gate teleportation and magic states, which are prepared at the logical level, increasing overhead to a degree that precludes near-term implementation. Here, we implement a small quantum algorithm, one-qubit addition, fault-tolerantly on a trapped-ion quantum computer, using the [Formula: see text] color code. By removing unnecessary error correction circuits and using low-overhead techniques for fault-tolerant preparation and measurement, we reduce the number of error-prone two-qubit gates and measurements to 36. We observe arithmetic errors with a rate of ∼1.1 × 10-3 for the fault-tolerant circuit and ∼9.5 × 10-3 for the unencoded circuit.

Two-Input Single-Output Boost Converter with Fault Tolerant Operation

The need for multi-input DC-DC converters is highly demanded in the context of the integration of different energy sources. When integrating several energy sources, such as batteries, solar PV arrays, fuel cells, etc., multi-input DC-DC converters preferred over multiple single-input DC-DC converters. The vast majority of MISO converters in use today only have one mode of operation, which is conventional operation using all sources. Very few MISO topologies have been presented with fault-tolerant capability. In this work, a non-isolated two-input single-output (MISO) boost converter is investigated for low-voltage DC (LVDC) applications with fault tolerant capability. The presented converter works in three modes, such as DC sources of equal values, DC sources of unequal values, and one of the DC sources that is faulty or out of order. The converter is simulated in a MATLAB/Simulink environment and experimentally validated using a scaled prototype. The outcomes demonstrate that the converter can integrate systems with two DC energy sources, accommodates DC sources of equal values, DC sources of unequal values, and works even when one of the DC sources is faulty or out of order. This work points out that the presented MISO converter would be an apt solution for integrating varying input voltage sources with fault-tolerant capability.

Design and analysis of a fault tolerance nano-scale code converter based on quantum-dots

Quantum-dot cellular automata (QCA), a nano-scale computer framework, is developing as a potential alternative to current transistor-based technologies. However, it is susceptible to a variety of fabrication-related errors and process variances because it is a novel technology. As a result, QCA-based circuits pose reliability-related problems since they are prone to faults. To address the dependability challenges, it is becoming increasingly necessary to create fault-tolerance QCA-based circuits. On the other hand, the applications of code converters in digital systems are essential for rapid signal processing. Using fault-tolerance XOR and multiplexer, this research suggests a nano-based binary-to-gray and gray-to-binary code converter circuit in a single layer to increase efficiency and reduce complexity. The fault-tolerance performance of the suggested circuits against cell omission, misalignment, displacement, and extra cell deposition faults has significantly improved. Concerning the generalized design metrics of QCA circuits, the fault-tolerance designs have been contrasted with the existing structures. The proposed fault-tolerance circuits' energy dissipation findings have been calculated using the precise QCADesigner-E power estimator tool. Using the QCADesigner-E program, the proposed circuits' functionality has been confirmed. The results implied the high efficiency and applicability of the proposed designs.

Fault Tolerance Analysis and Optimization of Centralized Control Platform Based on Artificial Intelligence and Optimization Algorithm

To enhance the reliability and self-healing of the system, the research on fault tolerance of the reconfigurable modular centralized control center is its development trend. Most of the previous research has focused on hardware redundancy. Improving fault tolerance performance is an essential topic in the research of centralized control platforms. Firstly, the problem of centralized fault tolerance in the working configuration of a reconfigurable manipulator is studied. The effect of each hinge on fault tolerance in the existing configuration is studied with the criterion of manoeuvrability and tolerable space. The fault module was first modelled to represent the system architecture information. A modular motion rule based on autonomous recombination technology is proposed. A self-organizing deformation algorithm with fault tolerance is studied. The fault tolerance of the motion pairs is compensated by adding a small number of motion pairs to ensure the configuration characteristics. With the addition of a failure compensation device, the joint’s range of motion was reduced, and the fault tolerance rate was enhanced. After the failure of the robot arm, the fault tolerant control method can still ensure that the robot arm can perform work in its tolerable working space. The test results show that the fault tolerance analysis method is practical and feasible. It lays a theoretical foundation for the application in aerospace, industry and other fields.

Analysis of the influence of winding phase shift on the comprehensive performance of multi-mode operation characteristics of dual-winding permanent magnet synchronous motor

Abstract The objective of this study is to investigate the electromagnetic properties of dual-winding permanent magnet synchronous motors with various winding phase shift angles, both under normal and fault-tolerant operating conditions. Initially, an analysis of the phase shift angle for the dual-winding motor windings is conducted, followed by the design of three distinct configurations with different phase shift angles for a 12-slot 10-pole motor. Subsequently, in the second section, a finite element model is developed to represent both healthy and faulty states of the 12-slot 10-pole dual-winding permanent magnet synchronous motor with varying phase shift angles. The third part of the study involves comparing and analysing the electromagnetic characteristics of the motor under different winding phase shift angles in healthy conditions. The fourth section delves into the comparison and analysis of the electromagnetic properties of motor faults across different winding phase shift angles. Finally, conclusions are drawn based on the analysis and summary of the electromagnetic characteristics of motor faults and health conditions across various winding phase shift angles.

A new configuration for enhanced integration of a battery–ultracapacitor system

The principal shortcoming of the batteries in electric vehicles is their limited specific power. The potential solution is having a hybrid energy storage system (HESS) that integrates the ultracapacitor (high specific energy) with the battery (high specific energy), thus ensuring high specific energy and power. Classically, a bidirectional DC–DC converter integrates the two sources, but the converter introduces a delay during the charging–discharging transition of the ultracapacitor. This work proposes a novel converter topology that interfaces the two sources, eliminating an existing transition delay, providing a fault-tolerant operation in case of a switch failure, and efficiently charging the ultracapacitor. Additionally, an algorithm is presented that facilitates energy sharing between the battery and the ultracapacitor, preventing overloading of the battery and ensuring that the ultracapacitor contributes to the peak load demand. The proposed configuration and energy management algorithm are validated experimentally using a 24V laboratory prototype.

Event‐triggered obstacle avoidance control for autonomous surface vehicles with actuator faults

AbstractThe article addresses the event‐triggered obstacle avoidance control problem for autonomous surface vehicles subject to actuator faults. In order to tackle the challenges presented by unknown actuator faults, internal model uncertainties, and external disturbances, we propose a fault‐tolerant control scheme that relies on an extended state observer to estimate the unknown parameters. In addition, considering the occurrence of actuator faults, a novel event‐triggered mechanism is developed to reduce wear of actuator and ensures the performance of system. On this basis, we employ backstepping technique and an improved artificial potential function methods to develop an event‐triggered obstacle avoidance control scheme with the capability of fault tolerance. This proposed control strategy ensures the uniform ultimate boundedness of tracking errors. In contrast to existing results, the presented control strategy simultaneously holds the performance of obstacle avoidance and fault tolerance and reduce the update frequency of actuators. The effectiveness of the provided control scheme has been confirmed through simulation.