A four-leg-based fault-tolerant matrix converter topology is proposed, along with switching function and space vector approaches for modulation schemes, to improve the reliability of matrix converter drives. The four-leg-based fault-tolerant structure utilizes an additional redundant phase module. Based on the reconfigured hardware topology, fault-tolerant modulation strategies with both switching function and space vector approaches are developed to provide the matrix converter drives with continuous and disturbance-free operation. Pulsewidth-modulated algorithms with closed-form expressions, based on a switching function matrix, are presented to synthesize redefined output waveforms with reconfigured converter structures. Furthermore, a space-vector-based scheme using the indirect equivalent circuit with the fictitious dc link is also developed for the fault-tolerant topology after failures. Experimental results show the feasibility of the proposed four-leg-based fault-remedial approach, along with the developed modulation techniques.

This paper presents a new diagnostic technique for the diagnosis of open-circuit faults in matrix converters operating with an Optimum Alesina-Venturini modulation scheme. Compared to previous diagnostic techniques developed for matrix converters, the technique proposed in this paper has the major advantage of not requiring the installation of any additional sensors in the converter besides the ones already present for control purposes. Hence, it can be easily integrated into the control platform of the converter at no additional cost. In addition to the diagnostic approach, a new fault-tolerant switching strategy is also presented so that after the appearance of an open-circuit fault, the matrix converter can continue to run although with degraded performance, until a repair action can be taken. Several simulation and experimental results are presented, demonstrating the effectiveness and applicability of the developed techniques.

This paper describes a novel fault-tolerant matrix converter motor drive system which requires an appropriate control strategy and the application of an effective fault detection technique. Two types of fault-tolerant matrix converter, a direct matrix converter and an indirect matrix converter, are proposed for a permanent magnet synchronous motor drive against open-circuit faults in safety-critical applications. A fault-tolerant control strategy is developed in order to maintain the continuous operation of the drive system with satisfactory performance. A high-speed fault detection strategy for detecting and identifying the faulty open-circuited switches located in the fault-tolerant four-phase direct matrix converter is also proposed. Simulation and experimental results are shown to demonstrate the effectiveness of the proposed fault-tolerant matrix converters and the developed fault detection strategy applied to the motor drive system under faulty operating conditions.

The matrix converter system is becoming a very promising candidate to replace the conventional two-stage ac/dc/ac converter, but system reliability remains an open issue. The most common reliability problem is that a bidirectional switch has an open-switch fault during operation. In this paper, a matrix converter driving a speed-controlled permanent-magnet synchronous motor is examined under a single open-switch fault. First, a new fault-detection method is proposed using only the motor currents. Second, a novel fault-tolerant switching strategy is presented. By treating the matrix converter as a two-stage rectifier/inverter, existing modulation techniques for the inverter stage can be reused, whereas the rectifier stage is modified by control to counteract the fault. However, the proposed techniques require no additional hardware devices or circuit modifications to the matrix converter. Experimental results show that the proposed method can maintain the motor speed with a maximum ripple of 2%-a fivefold improvement over the uncompensated system. The proposed method therefore offers a very economical and effective solution for the matrix converter fault tolerance problem.

A novel monitoring system, designed to detect open-circuit (OC) faults that occur in the matrix converter (MC) topology, is proposed in this work. In this monitoring system, a new diagnosis method is implemented which is based on the discrete wavelet transform analysis of the measured output current waveform. In order to ensure the effectiveness of the proposed method and its resistivity to erroneous fault detections, a fuzzy expert system is used in the designed monitoring system. The main advantages of the proposed method are that the implementation cost is minimized because no extra sensors are used and that no information from the control algorithm about the modulation parameters or the applied pulse sequence is required, reducing its implementation complexity and facilitating a more modular design. Additionally, it can be easily adapted to modified matrix topologies. A simple and robust method for the localization of the open-circuited transistor(s) within the identified faulty leg is also proposed. The proposed techniques are validated by simulation and experimental tests. The remedial operation of MC drives after the occurrence of an OC fault by using a redundant leg is also studied. The use of carrier-based modulation methods for this operation is experimentally validated, and related issues are discussed.

The monitoring of power converters is critical for obtaining systems with self-diagnostic capabilities and fault-tolerant features. This paper presents an analytical work concerning the operation of matrix converters (MCs) under the presence of open-circuit faults and discusses the applicability of a method for the diagnosis of this type of failures. The proposed method uses the absolute values of nine modulated error voltages for the continuous monitoring of the condition of the bidirectional switches of an MC. This method allows a fast detection and location of the faulty switches, independent of the modulation strategy of the converter, its voltage transfer ratio, output frequency, or type of load connected to it, both in steady-state and transient regimes. The theory, validated by simulation and experimental results, demonstrates the applicability of the proposed technique for the diagnosis of faults in MCs.