Open-phase Fault Research Articles

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.

A Novel Diagnosis Algorithm of Open Phase Fault in Grid-Connected Transformer for Energy Storage System

A Novel Diagnosis Algorithm of Open Phase Fault in Grid-Connected Transformer for Energy Storage System

Postfault Strategy of Universal Control for Dual Three-Phase PMSM Under Single Open-Phase Fault Considering Current Amplitude

Postfault Strategy of Universal Control for Dual Three-Phase PMSM Under Single Open-Phase Fault Considering Current Amplitude

Post-fault control for three-phase IM drives based on different transformations

ABSTRACT Field-Oriented Control (FOC) strategy is famous for its high accuracy. Nevertheless, the Conventional FOC (CFOC) technique application under the fault is limited. In this research, a novel post-fault control strategy based on the FOC method is developed for wye-connected three-phase Induction Motor (IM) drives under the Open-Phase Fault (OPF). The control system based on the dq model of the faulted wye-connected three-phase IM, where the FOC structure remains unchanged under the OPF, is used in the suggested post-fault control scheme. The proposed control method is derived based on the Conventional Current Transformation (CCT) and an Asymmetrical Voltage Transformation (AVT). The introduced post-fault control strategy in this research does not have difficult implementation and heavy calculation burden. The feasibility of the proposed post-fault control technique has been verified by experimentation. The experimental results are obtained with a three-phase IM with wye connection using a DSP/TMS320F28335 controller showing obviously the effectiveness of the proposed method compared to the conventional controllers during different situations.

A rotor open-phase imbalance protection for variable speed pumped storage unit based on rotation transformation fault component ratio

Doubly-fed variable speed pumped storage unit (VSPSU) adopts slip ring injection AC excitation mode, and its rotor side structure is complex and prone to open-phase faults. It is very important to configure specific open-phase imbalance protection to ensure its safe operation. Traditional doubly-fed motors only stay in the state monitoring stage for rotor electrical imbalance, which cannot meet the requirements of large-capacity VSPSU for fast, real-time, and high-reliability protection. Therefore, this paper proposes a VSPSU rotor open-phase imbalance protection method based on the rotation transformation fault component ratio (FCR). The fundamental frequency component and fault characteristic component of the stator current space vector are extracted by rotation transformation and FCR is calculated, and then different protection action modes are divided according to the amplitude of FCR. To realize the engineering application, a microcomputer protection algorithm suitable for the proposed protection method is further proposed, and then a complete microcomputer protection scheme is formed. Simulation and experiment results show that the proposed protection scheme has high sensitivity and fast action speed. At the same time, the proposed algorithm can be directly embedded in the existing microcomputer protection device to meet the needs of engineering applications.

Sensorless fuzzy-sliding mode control of five phases permanent magnet synchronous motor using MRAS: in three different operating modes

This paper presents a comprehensive study on sensorless control techniques for five-phase permanent magnet synchronous motors (5P-PMSMs). To optimize the speed control performance of (5P-PMSM), which has more advantages than its counterpart three-phase PMSM system, we utilized a combination of fuzzy logic and sliding mode control techniques to optimize the proposed sliding mode control. Additionally, the Model Reference Adaptive System (MRAS) is employed to estimate the speed and rotor position of the 5P-PMSM to enhance the robustness and adaptability of the control system. The modelling of the machine, detailed with a robust nonlinear strategy based on the sliding control, is introduced to track the system until the desired sliding surface is achieved first. To guarantee that the tracking errors converge, the sliding mode control has a chatter due to the discontinuous term. To mitigate the drawback, the proposed control is designed by combining SMC with fuzzy logic, enhancing the performance in a steady state. Examining the control performance of the integrated control fuzzy-SMC with MRAS in different operating modes, including three tests in reversal speed operation, open phase fault mode, and the low-speed operating mode under load torque. The main aim is to assess and analyze the robustness and performance of the proposed control strategy. The stability of the overall control system is examined using the Lyapunov theorem and Popov’s theory analysis of MRAS observer stability. The simulation results of the suggested control displayed by MATLAB-Simulink illustrate the effectiveness and adaptability of the sensorless control scheme across different operating conditions, offering promising prospects for practical implementation in industrial applications.

Online Fault Detection of Open-Circuit Faults in a DTP-PMSM Using Double DQ Current Prediction

This research proposes a strategy to diagnose open-phase faults (OPF) and open-switching faults (OSF) in dual three-phase permanent magnet synchronous motor (DTP-PMSM) inverters. The method is based on the dual d–q predictive current model and involves establishing a mathematical model and utilizing the finite control set model predictive current extraction technique to predict the motor current. It then analyzes the characteristics of the switching-tube current under both normal and fault conditions. Finally, a fault predictive current model is introduced and the residual is calculated based on the predicted fault current value and the actual measured current value to diagnose the inverter fault. The proposed method effectively overcomes misjudgment issues encountered in traditional open-circuit fault diagnosis of inverters. It enhances the system’s response speed during dynamic processes and strengthens the robustness of diagnosis algorithm parameters. The experimental results demonstrate that the proposed method can rapidly, effectively, and accurately diagnose open-circuit faults presented in this paper fastest within one-fifth of a current cycle. It achieves a diagnostic accuracy rate of 97% in the dual three-phase permanent magnet synchronous motor drive system.

Open-Circuit Fault Diagnosis of Three-Phase Permanent Magnet Machine Utilizing Normalized Flux-Producing Current

In this paper, an open-circuit fault diagnostic method is proposed for three-phase permanent magnet machines. By individually applying inverse coordination transformation to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis currents, per-phase current can be decomposed into flux- and torque-producing currents. Their post-fault behaviors are found to be highly related with the fault types and locations. Hence, the normalized flux-producing current can be used as a single fault index to detect and identify both open-switch and open-phase faults. Since the established fault index is close to zero, the proposed fault diagnostic method is naturally robust to load/speed variations. In addition, a low decision threshold can be set to reduce fault diagnostic time. The robustness and effectiveness of the proposed method are verified by the experiments on one prototype.

Analysis of a nuclear power plant’s responses to the open-phase fault of preferred power supply

This paper explores the phenomenon of open-phase fault of nuclear power plants for preferred power supply, focusing on three distinct scenarios, normal operation, start, and overhaul. For each scenario, the paper discusses the responses of existing relay protection devices, which are crucial for detecting and mitigating open-phase faults. These responses vary depending on the impedance at the fault location and the load rate of the plant. This paper highlights that open-phase faults can lead to three-phase imbalances in the power system, but their impact on voltage levels is not always straightforward due to the transformer and motor compensation effects. Additionally, the paper identifies blind zones in open-phase fault detection, where existing relays may fail to respond effectively, leading the plant to enter a station blackout state. In conclusion, the research underscores the importance of open-phase fault detection and protection in nuclear power plants. It reveals potential vulnerabilities in existing relay configurations and emphasizes the need for enhanced monitoring and safety measures to prevent extended plant operation under open-phase fault conditions.

A Square-Wave Voltage Injection Sensorless Control for Dual Three-Phase IPMs Robust to Open-Circuit Faults

Conventional sensorless control methods fail to estimate the accurate rotor position in case of open circuit faults (OCFs) in dual three-phase interior permanent-magnet machine (DT-IPM) drives, resulting in poor stability of the system. OCFs regularly contain open-phase faults (OPFs) and open-switch faults (OSFs). However, the current under OSFs can be considered as a combination of a one-half period of health status with a normal current and the other half period of OPF with zero current. Consequently, OSF is regarded as a generalized OPF. Based on the general solution to OCFs, a novel high-frequency (HF) square-wave voltage injection (HFSVI) sensorless control method is proposed for DT-IPMs at low speed to improve the fault-tolerance ability, which is robust to both OPFs and OSFs. With the help of vector space decomposition, the HFSVI is implemented in the decoupling space, where the effects of OCFs, e.g., varying amplitude and extra negative-sequence component of responded HF currents, can be compensated by HF currents in both αβ- and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xy</i> -subspaces in the rotor position estimation module. Compared with the non-compensation method, the proposed one is robust to parameter mismatches and only increases the computation burden slightly. Finally, experiments on a prototyped DT-IPM verify the proposed method.

Open-Phase Fault and Current Sensor Fault Diagnosis Based on Spatial Distributions of Phase Currents for Dual Three-Phase PMSM Drives

Open-Phase Fault and Current Sensor Fault Diagnosis Based on Spatial Distributions of Phase Currents for Dual Three-Phase PMSM Drives

Optimization of a 12-Slot/10-Pole, Asymmetrical, Six-Phase IPM Considering Healthy and Open-Phase Fault Post Operation in EV Applications

Optimization of a 12-Slot/10-Pole, Asymmetrical, Six-Phase IPM Considering Healthy and Open-Phase Fault Post Operation in EV Applications

Back Propagation Neural Network-Based Fault Diagnosis and Fault Tolerant Control of Distributed Drive Electric Vehicles Based on Sliding Mode Control-Based Direct Yaw Moment Control

Distributed-drive vehicles utilize independent drive motors on the four-wheel hubs. The working conditions of the wheel-hub motors are so harsh that the motors are prone to failing under different driving conditions. This study addresses the impact of drive motor faults on vehicle performance, particularly on slippery roads where sudden faults can lead to accidents. A fault-tolerant control system integrating motor fault diagnosis and a direct yaw moment control (DYC) based fault-tolerant controller are proposed to ensure the stability of the vehicle during various motor faults. Due to the difficulty of identifying the parameters of the popular permanent magnet synchronous wheel hub motors (PMSMs), the system employs a model-free backpropagation neural network (BPNN)-based fault detector. Turn-to-turn short circuits, open-phase faults, and diamagnetic faults are considered in this research. The fault detector is trained offline and utilizes rotor speed and phase currents for online fault detection. The system assigns the torque outputs from both healthy and faulted motors based on fault categories using sliding mode control (SMC)-based DYC. Simulations with four-wheel electric vehicle models demonstrate the accuracy of the fault detector and the effectiveness of the fault-tolerant controller. The proposed system is prospective and has potential for the development of distributed electric vehicles.

Dual-Vector-Based Predictive Torque Control for Fault-Tolerant Inverter-Fed Induction Motor Drives With Adaptive Switching Instant

Four-switch three-phase inverter (FSTPI) is widely applied as a fault-tolerant topology of six-switch three-phase inverter (SSTPI) with an open-phase fault or as a cost-effective topology due to the reduced semiconductor power switches. However, conventional single-vector-based predictive torque control (SV-PTC) for FSTPI-fed induction motor (IM) presents poor steady-state performance and requires high sampling frequency. To address these issues, a dual-vector-based PTC (DV-PTC) for FSTPI-fed IM with adaptive switching instant is proposed in this article. Therein, two optimal voltage vectors are determined in each sampling period, and a simplification strategy for selecting the optimal voltage vectors is established. A switching instant adaptation scheme is developed to improve the steady-state performance of machine control. An optimized overmodulation strategy is proposed to improve the transient-state performance of machine control and reduce the computational burden in digital implementation. Extensive experimental studies validate the effectiveness and superiority of the proposed DV-PTC scheme.

A High-Frequency Signal Injection-Based Sensorless Control Method Robust to Single and Double Open-Phase Faults for a Dual Three-Phase Motor

A High-Frequency Signal Injection-Based Sensorless Control Method Robust to Single and Double Open-Phase Faults for a Dual Three-Phase Motor

A novel multi-resolution network for the open-circuit faults diagnosis of automatic ramming drive system

The open-circuit fault is one of the most common faults of the automatic ramming drive system (ARDS), and it can be categorized into the open-phase faults of Permanent Magnet Synchronous Motor (PMSM) and the open-circuit faults of Voltage Source Inverter (VSI). The stator current serves as a common indicator for detecting open-circuit faults. Due to the identical changes of the stator current between the open-phase faults in the PMSM and failures of double switches within the same leg of the VSI, this paper utilizes the zero-sequence voltage component as an additional diagnostic criterion to differentiate them. Considering the variable conditions and substantial noise of the ARDS, a novel Multi-resolution Network (MrNet) is proposed, which can extract multi-resolution perceptual information and enhance robustness to the noise. Meanwhile, a feature weighted layer is introduced to allocate higher weights to characteristics situated near the feature frequency. Both simulation and experiment results validate that the proposed fault diagnosis method can diagnose 25 types of open-circuit faults and achieve more than 98.28% diagnostic accuracy. In addition, the experiment results also demonstrate that MrNet has the capability of diagnosing the fault types accurately under the interference of noise signals (Laplace noise and Gaussian noise).

Disturbance-Free Operation of Dual Three-Phase PM Machine Under Open-Phase Fault Considering Harmonic Current Injection

Disturbance-Free Operation of Dual Three-Phase PM Machine Under Open-Phase Fault Considering Harmonic Current Injection

A Fault-Tolerant Control Method for a PMSM Servo Drive System with a Four-Leg Inverter

In this paper, a fault tolerant control method is proposed for a permeant magnet synchronous motor (PMSM) servo drive system with four leg inverters to cope with the open phase fault. As one of common faults in the motor drive system, the open phase fault will degrade the control performance and efficiency. Even serious damage is caused in some extreme cases. Hence, it is meaningful to realize the fault tolerance of the drive system with open phase fault. The proposed method includes three parts: a torque-producing current calculator, phase voltage determination and voltage distributor. The torque-producing current calculator is designed by taking the third harmonic flux into consideration to calculate the torque-producing current. In the phase voltage determination, it is proved that the third harmonic flux has no influence on the line voltage equation. For healthy operation and fault operation, the voltage requirements in remaining healthy phases are determined based on the line voltages. Finally, two voltage distributors are designed to distributor the phase voltages into remaining inverter leg. The main difference of two voltage distributors is the polarity of two remaining voltage. Compared to the conventional method, the proposed method can reduce the torque ripple under a postfault condition. In addition, the controller structure will not be changed under a pre-fault and postfault condition. The proposed method has been validated by simulated results and experimental results.

Enhanced Fault Tolerance of Dual Three-Phase Permanent Magnet Motor With Three-Redundancy Control

This article proposes a novel three-redundancy control for the dual three-phase permanent magnet (DTP-PM) motor to enhance the open-phase fault tolerance. Three redundancies can be operated individually or synergistically. Hence, the faulty redundancy can be disconnected from the system to address the open-phase fault. The fault tolerance can be significantly enhanced. Primarily, the structure of the DTP-PM motor is analyzed. Six phases of the DTP-PM motor are separated into three sets of orthogonal phases and considered three two-phase motors. Therefore, three redundancies can be established. Since orthogonal phases provide a balanced structure, the magnetomotive force of each redundancy can be well controlled. Then, a DTP-PM motor control system with three redundancies is established, and a potential topology for the proposed strategy is also illustrated. Furthermore, the basic voltage vectors for each redundancy are investigated. The reference voltage vectors can be modulated expediently. Finally, some simulations and experiments are carried out, validating the feasibility and effectiveness of the proposed strategy.

General Online Current-Harmonic Generation for Increased Torque Capability With Minimum Stator Copper Loss in Fault-Tolerant Multiphase Induction Motor Drives

This paper proposes a current-reference generation method including current harmonic injection (CHI) for enhancing the torque capability of multiphase induction machines (IMs) with negligible space-harmonic effects, which is useful, e.g., during transient overload in electric vehicles. The admissible torque is increased because the harmonics reduce the phase-current peaks, so that the instantaneous peak-current constraint of the drive, usually associated with the converter ratings, is respected. The harmonics are injected in the so-called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x-y</i> subspaces of the IM, which do not produce torque, so that no torque ripple is introduced. The optimum harmonics are found online for each load, making it possible to minimize the stator copper loss (SCL) per torque in the entire torque range, ensuring full-range minimum loss (FRML). The method is suitable for healthy operation or open-phase faults, and for multiphase machines of any phase number and with either symmetrical or asymmetrical windings. Compared with FRML methods without CHI, higher torque is achieved. Although some techniques were available for increasing the torque capability by CHI, FRML was not attained, laborious offline optimization was needed, or they were only suitable for specific drives or for healthy conditions, unlike the proposal. Experimental results with a symmetrical six-phase IM are provided.