Open-switch Fault Research Articles

Diagnosis and Tolerant Control Methods for an Open-Switch Fault in a Vienna Rectifier

In this article, fault diagnosis and tolerant control methods are proposed for an open-switch fault in a Vienna rectifier. The proposed diagnosis method uses only the input currents to detect an open-switch fault without any additional hardware. In the proposed tolerant control, the offset voltage is used to restore the input currents when an open-switch fault occurs in a Vienna rectifier. In addition, the proposed tolerant control considers the balance of the neutral-point voltage. This method can improve the total harmonic distortion (THD) of the current and mitigate the dc-link voltage ripple. The effectiveness of the proposed open-switch fault diagnosis and tolerant control method is verified by simulated and experimental results.

An improved incipient whale optimization algorithm based robust fault detection and diagnosis for sensorless brushless DC motor drive under external disturbances

In general, unexpected failures in sensorless brushless DC (BLDC) motors can result in production downtime, costly repairs, and safety concerns. BLDC motors are commonly used in home appliances, the medical sector, aerospace, small-scale, and large-scale industries under uncertain operating conditions. Therefore, the fault detection and diagnosis (FDD) of BLDC motor drives can play a very important role in increasing their performance, reliability, robustness control, and operational safety under uncertain operating conditions in critical real-time applications. To satisfy these issues of hall effect sensor, misplacement of a hall-effect sensor, inverter IGBT open-switch fault diagnosis, failure of hall effect sensor, lack of robustness speed control of BLDC motor, which has received substantial interest in academic and industry sectors to establish the proposed work optimization techniques approach FDD strategy for speed control of sensorless BLDC motor under uncertain operating conditions. The proposed optimization techniques such as Bat Algorithm (BA), Grey Wolf Optimization (GWO), and Whale Optimization Algorithm (WOA) approach FDD strategies for BLDC motor drives. These FDD strategies simulated by the above optimization techniques on a sensorless BLDC motor with numerical Matlab/Simulink 2020a simulation results are verified. From the simulation results, out of three optimization techniques, the WOA-based FDD strategies are very effective for both bearing and stator winding faults detection and diagnosis in sensorless BLDC motor drives.

Operational strategy of nine‐phase induction machine under the open‐switch fault condition

Multiphase induction machines are getting more attention in industry and academia because of their advantages and need for electric vehicles as well as ship propulsion. In this case, more number of power electronics devices are required due to higher number of phases. Moreover, in comparison with electromechanical systems, the probability of failure in power electronic inverter switches will be high. A fault in a semiconductor switch, without any proper alleviating methods, may result in the failure of the entire drive. To improve the reliability of induction motor drives (IMD), there is a necessity to enhance the postfault operation of the inverters. In this article, the proposed nine-phase IMD incorporates simple mathematical equations and less circuit reconfigurations to work under conditions of open-switch fault in either a single switch or the inverter's entire leg. This enables the drive to achieve balanced steady-state operation with minimal deration in output power/torque under the fault conditions. In addition, alternative operational technique, which modulates the healthy phases of fault phase group with 50% duty ratio and minimal circuit reconfiguration, is discussed in this article. Moreover, all possible fault conditions and associated reconfiguration details of the drive are described in detail. To validate the proposed concepts, finite element method analysis is performed using ANSYS Maxwell, and experimentation is performed in the laboratory for both normal and fault conditions on nine-phase IMD.

Open switch fault diagnosis of cascade H-bridge multi-level inverter in distributed power generators by machine learning algorithms

In recent years, multi-level inverters have had remarkable applications in renewable energy sources, high voltage, and other high-power applications. The multi-level inverter has advantages like minimum harmonic distortion and can operate on several voltage levels. A multi-level inverter is being utilized for multipurpose applications such as transportation, communication, industrial manufacturing, aerospace active power filter, Static Var Compensator, and machine drive. Power electronics equipment reliability is very important, and to ensure a multi-level inverter system’s stable operation; it is important to detect and locate faults as quickly as possible. It is difficult to diagnose a fault in a multi-level inverter using a mathematical model because it consists of many switching devices, in this context and to improve fault diagnosis accuracy and efficiency of a cascaded multi-level inverter (CHMLI), a fault diagnosis strategy based on the probability principal component analysis (PPCA) might be utilized. Different machine learning algorithms are used to classify and diagnose the faults under different conditions in a cascaded H-bridge multi-level inverter (CHMLI). This paper presents the comparison of two different machine learning algorithms, such as support vector machine (SVM) and k-Nearest neighbors algorithm (k-NN), based on probabilistic principal component analysis (PPCA) for the effective open switch fault diagnosis in CHMLI employed in distributed generator units. PPCA is a useful technique used for optimizing and data processing without changing the input data’s original properties and characteristics. Using the phase shift pulse width modulation technique, the output voltage signals under different switching fault conditions if the CHMLI are taken as fault features. Both algorithms are used to identify and locate the fault under different modes in CHMLI of distributed generator units. The proposed fault diagnosis methods are compared using simulations and experimental results employing a field-programmable gate array (FPGA) controller. The developed system’s simulation and experimental results perform satisfactorily to detect the fault type, fault location, and reconfiguration. The fault diagnosis time using PPCA-SVM as a fault diagnosis tool for the simulation and experimental case is 0.065 ms and 2.12 ms, respectively. On the other hand, 347 ms and 415 ms fault diagnosis time for simulation and experimental case, respectively, are recorded for the PPCA-kNN based fault diagnosis technique. Therefore, the SVM-based fault diagnosis method is much more efficient and accurate than the k-NN based fault diagnosis method. Moreover, the proposed SVM-based fault diagnosis guaranteed high reliability for CHMLI.

Diagnosis and Fault-Tolerant Control of Six-Phase Wind Turbine under Multiple Open-Switch Faults

A new open-switch fault diagnosis method is proposed in this paper for the six-phase AC-DC converter based on the difference between the phase current and the corresponding reference using an adaptive threshold. The single and multiple open-switch faults are detected without any additional equipment and complicated calculations since the proposed fault detection method is integrated with the hysteresis controller. The proposed fault-tolerant technique reduces the value of overcurrent and total harmonic distortion on the side phases of the faulty one, by changing the switching signal of one switch in its opposite phase in some regions. This technique is performed without adding any legs, switches, or triode for alternating currents to the circuit. Finally, the proposed fault-tolerant technique is evaluated by MATLAB simulation and the results show its effectiveness.

Applicability Analysis of Indices-Based Fault Detection Technique of Six-Phase Induction Motor

The multiphase induction motor is considered to be the promising alternative to the conventional three-phase induction motor, especially in safety-critical applications because of its inherent fault-tolerant feature. Therefore, the attention of many researchers has been paid to develop different techniques for detecting various fault types of multiphase induction motors, to securely switch the control mode of the multiphase drive system to its post-fault operation mode. Therefore, several fault detection methods have been researched and adapted; one of these methods is the indices-based fault detection technique. This technique was firstly introduced to detect open-phase fault of multiphase induction motors. The main advantage of this technique is that its mathematical formulation is straightforward and can easily be understood and implemented. In this paper, the study of the indices-based fault detection technique has been extended to test its applicability in detecting some other stator and rotor fault types of multiphase induction motors, namely, open-phase, open-switch, bad connection and broken rotor bar faults. Experimental and simulation validations of this technique are also introduced using a 1 kW prototype symmetrical six-phase induction motor.

Adaptive Fast Fault Location for Open-Switch Faults of Voltage Source Inverter

In this paper, the issue of open-switch faults of voltage source inverter (VSI) is studied, an adaptive fast voltage-based real-time open-switch fault location method is proposed. Firstly, for each switching period, the voltage deviation is calculated by the expected voltage and estimated actual voltage, they are obtained via the mixed logical dynamic model (MLDM) and measured currents, respectively. Then, the voltage deviation of each phase is employed as a fault variable. By this way, avoiding the use of additional hardware, and embedding easily in system. Furthermore, considering the impact of sampling error, parameter error, dead time, delay time, and transition time, the adaptive threshold is designed. Finally, simulations and experiments are executed to verify the effectiveness of the proposed method.

Detection and isolation of current-sensor and open-switch faults in electric traction drives

In this work, a strategy for detection and isolation of current-sensors and open-switch faults in electric traction drives is proposed. An induction motor drive with only two current sensors is considered for the design of the proposed strategy. The current estimations from a simple open-loop observer are used to perform the fault detection and isolation. In addition, the same observer estimates the rotor flux angle required in a vector control strategy. Simulation results analyze the sensitivity to parametric and operating point variations. Moreover, the performance of the proposed approach is validated in the event of different types of faults, considering the dynamic behavior of an electric vehicle. Performed tests include gain and disconnection sensor faults and open-switch faults in the inverter.

Open-Switch Fault-Tolerant Operation of T-Type Active Neutral-Point-Clamped Converter Using Level-Shifted PWM

The T-type active neutral-point-clamped (T-ANPC) converter is an emerging hybrid multilevel topology, which owns superior characteristics such as low conduction losses, flexible in control. Reliability improvement is essential for the T-ANPC due to the large number of power switches. For this motivation, this brief develops a carrier-based fault-tolerant control strategy for the T-ANPC converter in the case of typical open-switch faults. A modified level-shifted pulse width modulation (LS-PWM) is employed to control the converter to obtain the desired outputs under single/multiple open-switch fault modes. The fault-tolerant operations with full and reduced power ratings are realized by rearranging the carriers and modulation signals of the LS-PWM. Finally, the feasibility and effectiveness of the proposed control strategy for the T-ANPC is evaluated experimentally.

ANN에 기반한 3상 PWM 컨버터의 다중 스위치 개방고장 진단 방법

For single and double open-switch faults in three-phase PWM (Pulse Width Modulation) converters, there are 21 types of fault modes depending on faulty switches, causing secondary faults in peripherals. In this paper, for diagnosing those fault modes, two-step technique based on ANNs using dc and THDs (Total Harmonics Distortions) of phase currents is proposed. Those dc and THDs are obtained through an ADALINE (Adaptive Linear Neuron) in real-time. In the first step, the ANN categorizes fault modes into six sectors in the three-phase plane. In the second step, the ANN localizes fault modes in each sector. Especially, the fault modes of both switches in the same legs are localized by comparing the number of the sampled zero current of the fault currents. The proposed method allows a real-time diagnosis with a simple and an high accuracy for the multiple open-switch faults and operates online. Simulations and experiments for a 3.7kW three-phase PWM converter confirmed the validity of the proposed diagnostic method.

Fault-Tolerant Control of Dual Three-Phase PMSM Drives With Minimized Copper Loss

In this article, a minimum-copper-loss fault-tolerant control scheme is proposed for open-phase fault and open-switch fault of dual three-phase permanent magnet synchronous motor (DT-PMSM) drives. Both the winding configurations of isolated neutral points and connected neutral points are studied in this article. In conventional minimum-copper-loss fault-tolerant control schemes, the constraints of sinusoidal phase currents result in insufficient copper-loss reduction. Different from them, the current references with the theoretically lowest copper losses are first derived and applied for different fault cases of DT-PMSM drives without using any unnecessary constraints in the proposed fault-tolerant control scheme. Thus, all phase currents in the proposed minimum-copper-loss fault-tolerant control scheme are optimized to be nonsinusoidal waveforms. Besides, the copper losses are further reduced by fully utilizing the remaining healthy switch in the faulty inverter leg for the open-switch fault of DT-PMSM drives with the proposed scheme. It has been theoretically and experimentally proved that the proposed fault-tolerant control scheme can reduce copper losses than all existing fault-tolerant schemes for both open-phase fault and open-switch fault in typical two-level voltage-source-inverter-fed DT-PMSM drives.

Open‐switch fault diagnosis in three‐level rectifiers based on selective calculation method for instant voltage deviation

This paper presents an open-switch fault detection, and identification method for a neutral-point clamped rectifier system. A new calculation method for phase-to-phase pole voltage deviations is proposed for reducing calculation errors. In this way, the more accurate diagnosis can be achieved. Both single-switch faults, and multiple-switch faults can be identified effectively by using fewer diagnostic variables, which makes the diagnostic method simpler, and more reliable. And all the variables can be simply calculated by signals which are available to the control system of the rectifier, avoiding the use of additional hardware. Moreover, different voltage thresholds are designed for different faulty feature sections to further reduce the diagnostic time. Additionally, a diagnostic result checking method is proposed to avoid the misdiagnosis when considering the effect of outer-switch faults. Finally, experiments are carried out, and the results show the robustness, and effectiveness of the proposed method.

Open-switch fault detection and isolation of DC-AC static inverter feeding induction machine

In the aim to ensure system reliability and monitoring of latent faults that decrease the installation's life and damage them in the short-term, this paper presents an online open-circuit switch fault diagnosis of a DC-AC inverter. The fault detection and isolation (FDI) employed method is articulated on two techniques based practically on stator currents analysis. For the first technique, the developed decision algorithm is based on d-q Park's vector components. In the second technique, fault diagnostic is achieved using normalised quantities of residues from the currents phases in ABC frame. When the open circuit switch fault occurs, the residual current vector between the stator currents with and without fault is calculated. After that, this vector will be evaluated by a decision algorithm. The drive chain modelling (power inverter-machine) and the monitoring algorithms are developed and established under the MATLAB/Simulink environment, where the results are presented and analysed. The feasibility and the effectiveness of the proposed techniques have been validated by simulation under different operating conditions.

Open-switch fault detection and isolation of DC-AC static inverter feeding induction machine

In the aim to ensure system reliability and monitoring of latent faults that decrease the installation's life and damage them in the short-term, this paper presents an online open-circuit switch fault diagnosis of a DC-AC inverter. The fault detection and isolation (FDI) employed method is articulated on two techniques based practically on stator currents analysis. For the first technique, the developed decision algorithm is based on d-q Park's vector components. In the second technique, fault diagnostic is achieved using normalised quantities of residues from the currents phases in ABC frame. When the open circuit switch fault occurs, the residual current vector between the stator currents with and without fault is calculated. After that, this vector will be evaluated by a decision algorithm. The drive chain modelling (power inverter-machine) and the monitoring algorithms are developed and established under the MATLAB/Simulink environment, where the results are presented and analysed. The feasibility and the effectiveness of the proposed techniques have been validated by simulation under different operating conditions.

Open-switch fault detection scheme in wind energy conversion system based on rotor currents analysis

To deal with the performance and service continuity of doubly fed induction generator (DFIG) based wind energy conversion systems (WECSs) during open-switch Insulated Gate Bipolar Transistor (IGBT) fault, a fault-tolerant Voltage Source Inverter (VSI) is proposed. The fault-tolerant VSI is designed with redundancy leg to replace the faulty leg after open-switch fault occurrence. In this investigation, we propose a new topology of DC-Bus tied DFIG based on uncontrolled rectifier in stator side. A Field Oriented Control (FOC) scheme is used in this paper to control the DFIGURE The open-switch IGBT fault is studied and a fault detection scheme based on rotor currents analysing within healthy and faulty conditions is proposed. Case study results show that the proposed fault-tolerant VSI can ensure the service continuity of DFIG-DC system. Experimental results are presented in this paper to validate the proposed fault detection scheme.

Time-Domain Characterization and Detection of Open Circuit Faults for H-Bridge Power Cell

This article presents the time-domain characterization of semiconductor open-circuit switch faults (OCSFs), such as an open switch with a healthy diode and switch–diode pair open for the H-bridge power cell. The inverter fault signatures under diagonally opposite open switch fault conditions with a healthy diode are approximately similar; therefore, this article presents a detection algorithm with a unique identification of each faulty switch within the H-bridge power cell. The proposed algorithm is also designed to detect and identify multiple OCSFs. The nonideal characteristics of semiconductor switches are considered for the identification of switch faults. The well-known unipolar sinusoidal pulsewidth modulation technique is used for the switching of semiconductor devices for the single power cell. The mathematical expressions have also been derived to find out the effect of the switch fault using a double Fourier integral solution and the switching states. The analytical expressions have been developed for the switched output voltage waveforms under ideal switching conditions. The behavior of the switch faults has been analyzed using inverter output voltage, load current, and total harmonic distortion of the pulsewidth-modulated inverter output voltage.

Open-switch fault detection scheme in wind energy conversion system based on rotor currents analysis

Open-switch fault detection scheme in wind energy conversion system based on rotor currents analysis

An Active FTC Strategy Using Generalized Proportional Integral Observers Applied to Five-Phase PMSG based Tidal Current Energy Conversion Systems

In recent years, multi-phase permanent magnet synchronous generators (PMSGs) have become attractive in the field of tidal current energy conversion systems (TCECS) due to their high-power density, reliability, and availability. However, external disturbances and malfunctions in power conversion chains will bring challenges to achieving stable and continuous tidal current energy harnessing. Using generalized proportional integral observers, an active fault-tolerant control (AFTC) strategy is therefore proposed for a five-phase PMSG based TCECS that is subjected to an open switch fault (OSF) in the generator side converter. This proposed AFTC strategy is applied into q-axis current control loops, which contain fault detection and compensation. The fault compensator will be smoothly activated using a sigmoid function once the OSF is detected. Finally, a small-scale power experimental platform emulating the TCECS is established in order to verify the feasibility and efficiency of the proposed FTC strategy. Experiment results show that this AFTC strategy can detect faults rapidly and effectively attenuate torque ripples in the post-fault operation mode.

ANN design of multiple open‐switch fault diagnosis for three‐phase PWM converters

In this paper, Artificial Neural Networks (ANNs) for diagnosing multiple open-switch faults in three-phase PWM (Pulse Width Modulation) converters are designed. For single and double open-switch faults in the converters, there are 21 types of fault modes, causing distorted phase currents. Since these abnormal currents can induce secondary faults in peripherals, the open-fault diagnosis is essentially required. In this paper, a two-step technique based on ANNs is utilized for the diagnosis of the multiple open-switch fault. First, dc and harmonic components of the currents are extracted by using an ADALINE (Adaptive Linear Neuron). In the first step, the ANN categorizes fault modes into six sectors by using dc components in the three-phase plane. In the second step, the ANN localizes fault modes by using dc components and the ratio of d–q axes currents THDs (Total Harmonics Distortions) in each sector. Especially, both switches open-faults in the same legs are localised by counting the sampled zero current of the fault currents. The proposed two-step technique allows a simple design of the ANNs for the diagnosis, and a short execution time about 22 s. Simulations and experiments for a 3.7 kW three-phase PWM converter confirmed the validity of the proposed diagnostic method.

Fault tolerant methods to reconfigure Multilevel level inverter for single and multiple open circuit switch faults

Device ratings limitations of two-level inverters restricted their applications and increased the demand for Multilevel inverters (MLI) for various high-power medium-voltage applications. However, it is not just the low device ratings that have enhanced the impact of MLI, but there are other key factors such as less good harmonic profile (filter size) and fault tolerance. Fault tolerance of MLI sustaining the various internal and external faults contributes to inverter reliability and plays a vital role to enhancing practical feasibility. However, achieving fault tolerant operation of MLI by control its switching operation rather than involving any external/auxiliary hardware is the most economical solution. Thus, considering the most popular modular redundant classical MLI i.e., Cascaded H-Bridge, this paper presents the simplest fault tolerant strategies practically used to reconfigure CHB from open circuit (oc) switch fault(s). The fault tolerant operation (FTO) is demonstrated considering three-phase eleven-level CHB in MATLAB/Simulink environment.