A fault-tolerant photovoltaic integrated shunt active power filter with a 27-level inverter

This paper introduces a fault-tolerant shunt active power filter (SAPF). The novility in of this work is that it poposes a solutions to increase the reliability of shunt active power filter to maintain its operation under a single-phase open-circuit fault in the SAPF. This will increase the reliability of the whole power system. The SAPF is composed of a 4-leg 27-level inverter based on asymmetric cascaded H-bridge topology. If an open-circuit fault is introduced to the operation of the SAPF, a special control technique will be implemented and the redundant leg of the SAPF will be activated. The fault-tolerant SAPF can do many tasks under healthy operating conditions and post and open circuit fault depending on the state of charge (SOC) of the batteries. It can mitigate harmonics in the power system, improve power factor in the system by injecting reactive power, and inject real power to the system. The proposed SAPF is tested and simulated in MATLAB/Simulink and the results have shown a significant improvement in total harmonics distortion (THD) of the source current from 13.9% to 3.9% under the normal operating condition and from 42% to 8.4% post and open circuit fault

Matrix converter open circuit fault diagnosis with asymmetric one zero SVM

An open-circuit fault detection and diagnosis strategy for a direct matrix converter is proposed in this paper. The current recirculating path during an open circuit condition is considered in detail with the aim of contributing more expert knowledge to the fault detection system for matrix converter. Simulation results are presented demonstrate the open circuit fault behavior of matrix converter. This expert knowledge is extremely important for the fault detection system to avoid false diagnosis. This work leads to the presentation of a reliable and fast fault detector for the Matrix Converter

Remedial brushless AC operation of fault-tolerant doubly salient permanent-magnet motor drives

The doubly salient permanent-magnet (DSPM) machine is a new class of stator-PM brushless machines, which inherently offers the fault-tolerant feature. In this paper, a new operation strategy is proposed and implemented for fault-tolerant DSPM motor drives. The key is to operate the DSPM motor drive in a remedial brushless ac (BLAC) mode under the open-circuit fault condition, while operating in the conventional brushless dc mode under normal condition. Both cosimulation and experimental results confirm that the proposed remedial BLAC operation can maintain the average torque, reduce the torque ripple, and retain the self-starting capability under the open-circuit fault. © 2006 IEEE.published_or_final_versio

Study of the performance of fault-tolerant multi-level inverter included in shunt active power filter

Nowadays, the large number of shunt active power filters (SAPF) is installed in many grid networks to eliminate the source currents harmonics and enhance power quality. These filters are installed in different places according to the filtration requirements. The connection between SAPF and grid network has a negative effect during the open-circuit fault of the insulated gate bipolar transistor (IGBT) switch of the SAPF. This paper proposes the application of the new diagnostic method based on the trigonometric circle and mean value variations techniques to the early detection and precise location of the open-circuit fault of the IGBT switches, and the inclusion of the modified reconfigurable inverter topology to allow the perfect continuity of the filter currents, and improve the diagnostic of the open-circuit fault. A single-sided amplitude spectrum technique (SSAS) is applied on the source currents to get the THDi% value. The obtained simulation results prove, the great success of the proposed diagnostic method, the ability of the modified reconfigurable inverter to be adapted to the grid network, the short response time between the diagnosis and the reconfiguration process is about 7 ms which is very sufficient to guarantee the rapid continuity of the shunt active power filter

Matrix converter open circuit fault behavior analysis and diagnosis with a model predictive control strategy

A novel fast and reliable open circuit fault diagnosis strategy for a Matrix Converter with a Finite Control Set Model Predictive Control strategy is proposed in this paper. Current sensors are located ahead of the clamp circuit to measure the output currents in order to improve the speed of fault diagnosis. In addition, the current recirculating path during a single open circuit switch fault condition is given in detail with the aim of contributing more expert knowledge to the fault diagnosis. The proposed fault diagnosis method is applicable over the whole range of modulation index

Sensorless Control of a Fault-Tolerant Multi-Level PMSM Drive

This paper presents a new technique to track the saliency position in a permanent magnet synchronous motor (PMSM) post a single phase open-circuit fault. The PMSM is driven by a fault-tolerant multi-level inverter that is utilized to implement a fault-tolerant control strategy to minimize system performance degradation post the fault.The fault-tolerant multi-level inverter is consisting of a number of insulated-gate bipolar transistors (IGBTs). The dynamic current reponses of the PMSM motor due to the switching actions of these IGBTs are used extract the saliency position. This process is not introducing any modification to the operation of the fault-tolerant multil-level inverter as it uses only the fundamental pulse width modulation (PWM) waveform. Moreover,it considers the modifications introduced to the PMSM motor and the multi-level inverter post the fault.Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by a fault-tolerant four-leg multi-level inverter over a wide range of speeds in the case of a single-phase open circuit fault

Universal Short-Circuit and Open-Circuit Fault Detection for an Inverter

Short-circuit and open-circuit faults of an inverter’s power device often lead to catastrophic failure of the entire system if not detected and acted upon within a few microseconds, particularly for emerging wide bandgap (WGB) power semiconductors. While a significant amount of research has been done on the fast and accurate protection and detection of short-circuit faults, there has been less success corresponding to the research on open-circuit faults. Common downfalls include protection and detection that are too application-specific, take longer than a couple of microseconds, and are not cost-efficient. This study proposes a new open-circuit fault protection and detection system integrated with a pre-existing short-circuit system called desaturation protection. First, a literature review is conducted to confirm the necessity of the new protection and detection scheme. Second, the operation principle of the newly proposed protection and detection circuitry is discussed, and design considerations are given. Third, a comprehensive case study revolving around implementing the new protection and detection system is conducted using Synopsys/Saber simulation software. Fourth, an experiment is devised and constructed to showcase the protection and detection scheme’s success, effectiveness, and adaptability in a real-world environment. Fifth, concluding remarks are given, summarizing all the work presented in this study. The results of testing the proposed system illustrate the success and reliability of the new fault protection and detection system

Open circuit fault diagnosis technique for inverter switches and gate drive malfunction

Open circuit faults (OCFs) in voltage source inverters (VSIs) can significantly affect their performance and reliability. In this paper, a novel fault diagnosis technique (FDT)is presented for the detection and classification of two types of OCFs in VSIs: gate drive malfunction (GDM) and open switch fault (OSF). the effect of these OCFs on the output current of the VSI is analysed, this shows that they can be identified and distinguished using the average and root mean square (RMS) ratio of the current parameters. The proposed FDT is simple to implement and can identify switch faults with quick response, without the need for additional equipment. In this work the authors adopted the ensemble bagged tree classification method to detect and classify the GDM and OSF, the results show the credibility of the proposed technique in identifying different open circuit faults

An On-line Diagnostic Method for Open-circuit Switch Faults in NPC Multilevel Converters

On-line condition monitoring is of paramount importance for multilevel converters used in safety-critical applications. A novel on-line diagnostic method for detecting open-circuit switch faults in neutral-point-clamped (NPC) multilevel converters is introduced in this paper. The principle of this method is based on monitoring the abnormal variation of the dc-bus neutral-point current in combination with the existing information on instantaneous switching states and phase currents. Advantages of this method include simpler implementation and faster detection speed compared to other existing diagnostic methods in the literature. In this method, only one additional current sensor is required for measuring the dc-bus neutral-point current, therefore the implementation cost is low. Simulation and experimental results based on a lab-scale 50 kVA adjustable speed drive (ASD) with a three-level NPC inverter validate the efficacy of this novel diagnostic method