scholarly journals A Novel Fault-Tolerant Control of Modular Multilevel Converter under Sub-Module Faults based on Phase Disposition PWM

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 20 ◽  
Author(s):  
Yin Jingyuan ◽  
Wen Wu ◽  
Wei Tongzhen ◽  
Wu Xuezhi ◽  
Huo Qunhai
Keyword(s):  
Control Strategy ◽  
Pulse Width Modulation ◽  
Fault Tolerant ◽  
Fault Tolerant Control ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Modulation Wave ◽  
Zero Sequence ◽  
Simulation And Experiment ◽  
Zero Sequence Voltage

Each arm of modular multilevel converter (MMC) consists of a large number of sub-module (SM) units. However, it also increases the probability of SM failure during the long-term system operation. Focusing on the fault-tolerant operation issue for the MMC under SM faults, the traditional zero-sequence voltage injection fault-tolerant control algorithm is analyzed detailed and its disadvantages are concluded. Based on this, a novel fault-tolerant control strategy based on phase disposition pulse-width modulation (PD-PWM) is proposed in this paper, which has three main benefits: (i) it has carrier and modulation wave dual correction mechanism, which control ability is more higher and flexible；(ii) it only needs to inject zero-sequence voltage in half a cycle of the modulation wave, which simplifies the complexity of traditional zero-sequence voltage injection control algorithms and much easier for implement; (iii) furthermore, the zero-sequence voltage can even be avoided injecting under the symmetrical fault conditions. Finally, the effectiveness of the proposed control strategy is verified with the simulation and experiment studies under different fault conditions.

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 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 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.

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