scholarly journals Fault-Tolerant Control Strategy for Neutral-Point-Clamped Three-Level Inverter

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Yanxia Shen ◽  
Beibei Miao ◽  
Dinghui Wu ◽  
Kader Ali Ibrahim
Keyword(s):  
Control Strategy ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Neutral Point ◽  
Control Technique ◽  
Action Time ◽  
Addition And Subtraction

A fault-tolerant control technique is discussed for the Neutral-Point-Clamped (NPC) three-level inverter, which ensures that the NPC inverter operates normally even under device failures. A two-level leg is added to the NPC inverter; when the device open circuit fault occurs, the load of this faulty phase is connected to the neutral point of this two-level leg through the bidirectional thyristors. An improved Space Vector Pulse Width Modulation (SVPWM) strategy called “addition and subtraction substitution SVPWM” is proposed to effectively suppress fluctuation in capacitor neutral-point voltages by readjusting the sequence and action time of voltage vectors. The fault-tolerant topology in this paper has the advantages of fewer switching devices and lower circuit costs. Experimental results show that the proposed fault-tolerant system can operate in balance of capacitor neutral-point voltages at full output power and the reliability of the inverter is greatly enhanced.

scholarly journals Improved SVPWM Fault-Tolerant Control Strategy for Five-Phase Permanent-Magnet Motor

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4626 ◽  
Author(s):  
Liang Xu ◽  
Wenxiang Zhao ◽  
Guohai Liu
Keyword(s):  
Permanent Magnet ◽  
Control Strategy ◽  
Pulse Width Modulation ◽  
High Efficiency ◽  
Fault Tolerant ◽  
Control Strategies ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Permanent Magnet Motors ◽  
Permanent Magnet Motor

Multiphase permanent-magnet motors have received a lot of attention in the past few years owing to the merits of high power density, high efficiency and high fault-tolerant capability. Particularly, high fault tolerance is very desirable for safety-critical applications. This paper proposes an improved space vector pulse-width modulation (SVPWM) fault-tolerant control for five-phase permanent-magnet motors. First, generalized five-phase SVPWM fault-tolerant control is deduced and analyzed based on single-phase open-circuit fault, thus obtaining various SVPWM fault-tolerant control strategies and yielding a greatly increased capacity to enhance fault-tolerant performance of motor. Then, an improved SVPWM fault-tolerant control strategy with increased DC bus voltage utilization and reduced current harmonics is proposed and compared with the traditional one. Last, effectiveness and superiority of the proposed control strategy is verified by both simulation and experimental results on a five-phase permanent-magnet motor.

scholarly journals Fault-Tolerant Control Strategy with Asymmetric Phase Currents for Single to Four-Phase Open-Circuit Faults of Six-Phase PMSM

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3163
Author(s):  
Chen Huang ◽  
Lidan Zhou ◽  
Zujia Cao ◽  
Gang Yao
Keyword(s):  
Working Conditions ◽  
Control Strategy ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Time Varying ◽  
Electromagnetic Torque ◽  
Control Loops ◽  
Phase Current ◽  
Multi Phase

Multi-phase motors and generators are regarded with great fault tolerance capability, especially on open-circuit faults. Various mathematics analytical methods are applied for their fault control. In this paper, a fault-tolerant control strategy with asymmetric phase current for the open-circuit faults with arbitrary phases in the six-phase PMSM (six-phase permanent magnetic synchronous motor, 6P-PMSM) system, is proposed for better electrical and dynamical performance of the machine. An innovative mathematical model for PMSM under one to four-phase-open circuit faults are established considering the asymmetry of the machine. Combining with time-varying relations in machines’ working conditions, targeted decoupling transformation matrixes of every kind of open-circuit faults are settled by voltage equations under different faults. Modified control strategy with a connection between the neutral point and the inverter’s DC side is presented, which aims at increasing the system redundancy and reducing the amplitude of phase currents. Besides, improved control loops with two layers are put forward as well, with which the PMSM system acquires fewer harmonics in phase current and smoother electromagnetic torque. Simulation and experimental results of open-circuit faults are provided for verification of the theoretical analysis.

scholarly journals A Fault-Tolerant Control Strategy of Modular Multilevel Converter with Sub-Module Faults Based on Neutral Point Compound Shift

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 876 ◽  
Author(s):  
Qinyue Zhu ◽  
Wei Dai ◽  
Lei Guan ◽  
Xitang Tan ◽  
Zhaoyang Li ◽  
...  
Keyword(s):  
Fault Tolerance ◽  
Control Strategy ◽  
Control Method ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Neutral Point ◽  
Modular Multilevel Converter ◽  
Phase Voltage ◽  
Multilevel Converter ◽  
Shift Control

In view of the complex calculation and limited fault tolerance capability of existing neutral point shift control algorithms, this paper studies the fault-tolerant control method for sub-module faults in modular multilevel converters on the basis of neutral point compound shift control strategy. In order to reduce the calculation complexity of shift parameters in the traditional strategy and simplify its implementation, an improved AC side phase voltage vector reconstruction method is proposed, achieving online real-time calculation of the modulation wave adjustment parameters of each phase required for fault-tolerant control. Based on this, a neutral point DC side shift control method is proposed to further improve the fault tolerance capability of the modular multilevel converter (MMC) system by compensating the fault phase voltage with non-fault phase voltage. By means of the compound shift control strategy of the DC side and AC side of the neutral point, an optimal neutral point position is selected to ensure that the MMC system output line voltage is symmetrical and the amplitude is as large as possible after fault-tolerant control. Finally, the effectiveness and feasibility of the proposed control strategy are verified by simulation and low-power MMC experimental system testing.

scholarly journals New Diagnosis and Fault-Tolerant Control Strategy for Photovoltaic System

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Hassan Abouobaida ◽  
Younes Abouelmahjoub
Keyword(s):  
Control Strategy ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Maximum Power ◽  
Photovoltaic System ◽  
Normal Operation ◽  
Switching Frequency ◽  
Point Tracking ◽  
Interleaved Boost Converter

This paper discusses open-circuit fault (OCF) diagnosis and fault-tolerant control strategy (FTCS) of a nonisolated DC-DC converter. The photovoltaic power conversion structure (PPCS) consists of a photovoltaic generator and an interleaved Boost converter (IBC). The maximum power point tracking (MPPT) control of the IBC ensures operation at maximum power. The design of the nonlinear Backstepping control is detailed based on the equivalent average model of IBC, and the stability is studied using Lyapunov’s theorem. The proposed OCF fault detection is based on sampling the voltage across the inductor at a much higher frequency than the switching frequency. In an OCF situation occurrence and a high control signal state, the detection of three negative samples is a condition for signaling the presence of an OCF fault; the photovoltaic system continues its normal operation. The simulation results show the validity of the proposed FTCS. The proposed diagnosis and control strategy improves the performance of the IBC in terms of cost, reliability, and service continuity.

Sign in / Sign up

Export Citation Format

Share Document