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1

Fault-tolerant control for three-phase three-level T-type inverters with a redundant leg

Chen Danjiang, Zheng Liyuan

Archives of Electrical Engineering

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2022

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Vol. 71, nr 4

931--948

EN

Three-level T-type inverters have lower total harmonic distortion in output voltage, higher power density and lower voltage stress of power switches compared with conventional two-level inverters and have been widely used in applications with a wide-power range. Reliability improvement is particularly important for the T-type inverters because of the increased number of power switches and high system complexity. This paper proposes a fault-tolerant topology, which is constructed by adding a redundant leg including halfbridge switches and neutral-point switches connected between the DC bus capacitors and the DC-link midpoint of the conventional T-type inverter. In addition, an after-fault control strategy is proposed based on the results of a fault diagnosis method using bridge voltage. The fault-tolerant control of the open-circuit fault of the power switches and the phase-leg fault can both be achieved by the proposed method. Experimental results are given to verify that the proposed fault-tolerant three-level T-type inverter can output the full voltage level and power during the fault-tolerant operation based on the proposed control strategy.

2

Fault diagnosis of T-type three-level inverter based on bridge voltages

Chen Danjiang, Liu Yutian, Zhang Shaozhong

Archives of Electrical Engineering

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2021

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Vol. 70, nr 1

73--87

EN

Multilevel inverters have been widely used in various occasions due to their advantages such as low harmonic content of the output waveform. However, because multilevel inverters use a large number of devices, the possibility of circuit failure is also higher than that of traditional inverters. A T-type three-level inverter is taken as the research object, anda diagnostic study is performed on the open-circuit fault of insulated gate bipolar transistor (IGBT) devices in the inverter. Firstly, the change of the current path in the inverter when anopen-circuit fault of the device occurred, and the effect on the circuit switching states andthe bridge voltages were analyzed. Then comprehensively considered the bridge voltages,and proposed a fault diagnosis method for a T-type three-level inverter based on specificfault diagnosis signals. Finally, the simulation verification was performed. The simulation results prove that the proposed method can accurately locate the open-circuit fault of theinverter device, and has the advantage of being easy to implement.

3

Open-circuit fault diagnosis in three-phase induction motor using model-based technique

Aswad Raya A. K., Jassim Bassim M. H.

Archives of Electrical Engineering

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2020

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Vol. 69, nr 4

815--827

EN

The presence of an open-circuit fault subjects a three-phase induction motor to severely unbalanced voltages that may damage the stator windings consecutively causing total shutdown of systems. Unplanned downtime is very costly. Therefore, fault diagnosis is essential for making a predictive plan for maintenance and saving the required time and cost. This paper presents a model-based diagnosis technique for diagnosing an open-circuit fault in any phase of a three-phase induction motor. The proposed strategy requires only current signals from the faulty machine to compare them with the healthy currents from an induction motor model. Then the errors of comparison are used as an objective function for a genetic algorithm that estimates the parameters of a healthy model, which they employed to identify and localize the fault. The simulation results illustrate the behaviours of basic parameters (stator and rotor resistances, self-inductances, and mutual inductance) and the number of stator winding turn parameters with respect to the location of an open-circuit fault. The results confirm that the number of stator winding turns are the useful parameters and can be utilized as an identifier for an open-circuit fault. The originality of this work is in extracting fault diagnosis features from the variations of the number of stator winding turns.

4

Analysis of chosen IGBT faults diagnostic variables in AC/DC line-side converter

Sobański P., Orłowska-Kowalska T.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 5

66--71

EN

In this paper single IGBT open-circuit faults symptoms analysis in the voltage-oriented-controlled AC/DC converter has been carried out. In accordance with the research, chosen diagnostic signals have been selected and diagnostic variables have been defined in order to evaluate transistor faults diagnostic methods. A main goal of this article was to test and confirm an effectiveness of chosen well-known diagnosis techniques for single-switch IGBT open-circuit faults in the two-level three-phase voltage inverters, in case of a reversible AC/DC line side converter, even under asymmetric power supply. Presented results have a comparative character and they have been verified by simulation model of the AC/DC converter control structure based on a measured or an estimated grid voltage.

PL

W artykule przedstawiono wybrane symptomy uszkodzeń tranzystorów IGBT, polegających na braku przewodzenia prądu, w przekształtniku energoelektronicznym AC/DC sterowanym metodą orientacji wektora prądu względem wektora mierzonego lub estymowanego napięcia sieci. Wyselekcjonowano sygnały diagnostyczne oraz zdefiniowano zmienne diagnostyczne, na podstawie których sformułowano reguły umożliwiające identyfikację uszkodzonych tranzystorów prostownika. Głównym celem pracy było zbadanie możliwości implementacji w układach przekształtnikowych AC/DC o dwukierunkowym przepływie energii znanych metod diagnostyki awarii tranzystorów dwupoziomowego falownika napięcia, również w warunkach asymetrii sieci zasilającej prostownik. Przedstawione wyniki badań mają charakter porównawczy i zostały uzyskane za pomocą symulacyjnych modeli przekształtnika AC/DC zarówno w układzie regulacji z pomiarem jak i estymacją napięć sieci zasilającej.