This paper presents a real-time diagnostic algorithm for insulated-gate bipolar transistor open-circuit faults in three-level neutral-point-clamped rectifiers. This algorithm is based on the instant voltage error in the converter and requires only signals already available to the control system, avoiding the use of additional hardware. The algorithm is independent from the load and from the used control strategy and provides very fast detection and identification of the fault, with diagnostic times as low as two sample periods (in favorable conditions). Experimental results are presented for the operation of the rectifier with two distinct control and modulation strategies and in different conditions. Results show the algorithm's speed, effectiveness, and robustness.

In this paper, new techniques are presented to improve the performance of Optimal Switching Vector Model Predictive Control. A well-defined analytic technique is proposed for the real-time adjustment of dynamic weighting factors, as well as a new objective function formulation. These techniques provide a dynamic controller behavior, automatically adapted to distinct operating points. This ensures better steady-state performance in different conditions while improving simultaneously the dynamic response. The proposed controller presents a lower computational load than the conventional formulation and its design requires less extensive testing. General guidelines are presented to guide the user in the controller design. Simulation and experimental results are presented, demonstrating the advantages and superior performance of the proposed controller.

This study presents a new fault‐tolerant predictive power control strategy for doubly‐fed induction generators (DFIGs) used in wind energy applications, with the rotor fed by a three‐level neutral point clamped converter. The proposed control strategy is able to maintain the system in operation with a good performance after the occurrence of either open‐circuit (OC) or short‐circuit faults in the insulated‐gate bipolar transistors (IGBTs) of the rotor‐side converter (RSC), thus reducing the downtime and maintenance costs of wind turbines. The fault‐tolerant strategy takes advantage of the discrete nature and flexibility of finite control set model predictive control strategies and restricts the possible switching states of the power converter according to the type of fault and its location. A diagnosis method for IGBT OC faults in the RSC, based on voltage errors, is also proposed for the considered system. This method uses the estimated rotor voltages from the DFIG model, thus avoiding the use of any extra sensors. Accurate and fast detection of OC faults in both interior and exterior IGBTs is achieved throughout the entire DFIG operational range. The effectiveness of the fault diagnosis method and fault‐tolerant control strategy is validated with several experimental results.

Some of the main concerns in the use of power converters are their reliability and the ability to detect and maintain operation when in fault. Many techniques have been proposed to identify and respond to faults in Neutral-Point-Clamped converters. Most of these methods, however, require additional hardware and/or changes in the topology. In this paper, a NPC rectifier is investigated, including the impacts of each possible semiconductor fault in the operation. Methods for fault diagnosis and fault tolerant operation are presented. The presented diagnostic method does not require additional hardware and is not affected by the load. Open-circuit and short-circuit faults are detected in both IGBTs and diodes. Fault tolerant operation with different levels of action is presented. Experimental results are presented to demonstrate the effectiveness of the methods.