Reliability and Real-Time Failure Protection of the Three-Phase Five-Level E-Type Converter

Power electronic converters have a heavily influence in our lifestyle, as they are used today in several applications, such as in-home and office appliances, electromedical apparatus, industry machine tools, as well as in electrical energy transmission and distribution systems. Power electronic converters are based on using fast-switching power semiconductors, which allow the desired shaping of the output electrical quantities waveforms, however, these power devices are also the most fragile component of the power conversion apparatus. Thus, to ensure safety and reliability of the power conversion system, a fault detection method must be suitably embedded in the control system. When a failure occurs, the fault detection and protection system become the most important function of the converter control unit. This article is devoted to the theoretical analysis of all the possible faults occurring in the three-phase five-level E-type converter (3Φ5L E-type converter) and based on such an analysis, a suitable fault management strategy is proposed. Fault effects are initially analyzed on the long-term time scale, from 10 μs up to 100 ms. The fault effects, the detectability, and the safety shutdown actions are identified and summarized. The analysis is covered by simulation results performed in MATLAB/Simulink. Following the theoretical analysis, a control algorithm has been implemented in field-programmable gate array using LabVIEW. Finally, experimental tests have been performed on a prototype of the proposed multilevel converter in order to validate the proposed approach to management of the envisaged fault conditions.