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This paper deals with a hybrid fault-tolerant converter topology. It is performed through the connection of a classical three-phase three-level neutral-point-clamped (3L-NPC) converter with a fourth three-level flying capacitor (3L-FC) leg. The 3L-FC leg actively balances the 3L-NPC neutral-point voltage. For normal operation mode, this paper proposes a mathematical design of the filter needed to connect these two different topologies. Experimentally, and thanks to the already existing decoupling capacitors of the 3L-NPC converter, this filter requires the addition of only one low size inductance. When one fault of the power switch of the 3L-NPC occurs, this paper proposes a hardware reconfiguration technique based on only two fuses and one thyristor per leg allows a safe postfault operation recovery. This is achieved thanks to a simple fault-detection method and a new technique that combines fault leg isolation and corresponding phase postfault connection to the neutral point. Also, a dedicated field-programmable gate array (FPGA)-based control of the reconfigured converter is synthetized to ensure power system availability under fault operation mode. The converter fault-tolerant capabilities are addressed through simulation results and original overall experimental validations of the fault detection and isolation and the postfault operation steps, carried out on a 15-kW prototype converter. [ABSTRACT FROM AUTHOR]

This study details a three-level hybrid fault-tolerant converter. The definition of an original decoupling solution between the fourth flying capacitor (FC) leg and the three neutral point (NP) clamped-based phases overcomes topology hybridisation issues. Under normal conditions, a control strategy of the FC-based leg leads to a converter NP voltage balance, and decreases the DC side capacitors' volume and cost. Under fault conditions, the presented fault isolation and converter reconfiguration strategies generate a post-fault converter, which is able to operate safely with the added FC-based leg. The proposed topology is an interesting trade-off between converter fault-tolerant capability and its complexity and offers the ability to be simply reconfigured and controlled in the case of switch fault occurrence. Two operation modes under fault conditions are presented and their performances are shown and discussed through simulation results and first experimental tests. [ABSTRACT FROM AUTHOR]

This paper investigates the field-programmable gate array (FPGA) implementation of a fault-tolerant space vector-hysteresis current control (SV-HCC) for three-phase grid-connected converter. The proposed control ensures continuous operation despite of an open-circuit fault in one grid current measurement circuit (caused by defected cables, lines or connectors at the output of the current measurement circuit). It is based on hardware redundancy of current measurement circuits for fault detection and isolation. The faulty measured current is identified through the computation of residuals with well-defined thresholds. Thanks to the high computation capabilities of FPGAs, the implemented fault-tolerant SV-HCC is executed with a very high sampling frequency and very low execution time. As a consequence, the defined theoretical thresholds remain available for the experimental tests. Several experimental results, carried out on FPGA-based prototyping platform, are given in order to illustrate effectiveness and reliability of the proposed fault-tolerant SV-HCC. [ABSTRACT FROM AUTHOR]

This paper deals with embedded real-time (RT) simulators applied in power electronic applications and implemented in low-cost field-programmable gate arrays. Indeed, such simulators' intellectual properties (IPs) are not only intended for hardware-in-the-loop (HIL) testing but also can be advantageously embedded within digital controllers to ensure functions such as observation, estimation, diagnostic, or health monitoring. Conversely, to the HIL case, the main challenge when designing such simulators' IPs is to cope with their complexity having in mind that, in the case of embedded systems, the available hardware resources are limited due to the cost. Furthermore, this challenge is strengthened by the need of very short simulation time steps that is typically the case when simulating power converters. By this way, this paper presents the design of an embedded RT simulator of a three-phase grid-connected voltage-source rectifier, based on the associated discrete circuit modeling approach. This IP is associated with the one of a three-phase $RL$ filter, and both are implemented within the rectifier controller to estimate the grid currents. The latter is injected in the controller when a fault is detected in the current sensors. The ability of this estimator to guarantee the service continuity in case of faults has been validated through HIL tests and experiments. [ABSTRACT FROM PUBLISHER]

This paper presents an easy and a robust sensor fault detection and isolation (FDI) and fault tolerant control (FTC) of a single phase PWM rectifier for electrical railway traction application. Catenary current sensor and dc link voltage sensor failures are considered. The FDI method is based on observers and residual generation. The different FDI algorithm steps allow a good detection and isolation of the sensor fault and identify the faulty sensor. The reconfiguration strategy consists of two steps with open loop control and closed loop control working. Simulation results are presented to illustrate the good performance of the FTC procedure. Experimental results are also presented to show the effectiveness of the proposed FDI and FTC algorithms and good performances of the rectifier after the reconfiguration. [ABSTRACT FROM AUTHOR]

This paper focuses on sensor fault detection and isolation (FDI) for electrical systems. A new, easy and fast FDI algorithm is proposed, keeping system performances unchanged under certain faulty sensor conditions when reconfigurations are available. The proposed FDI algorithm is derived from a parity space approach and is based on temporal redundancies. It is insensitive to parameter variations since no model knowledge is required. Also, it is available for a large class of electrical systems such as single- or three-phase power converters, dc or ac electrical drives, etc. Moreover, the residual threshold used for FDI is accurately defined and is suitable for the whole operating range. Simulations results are presented to illustrate the good functionality of theoretical developments. Numerous experimental results are also shown to validate the effectiveness of the proposed FDI algorithm and to highlight its advantages for the control of electrical systems. [ABSTRACT FROM AUTHOR]