Open-Switch and Open-Clamping Diode Fault Diagnosis for Single-Phase Five-Level Neutral-Point-Clamped Inverters

Abstract

In this paper, a fast and efficient open-circuit switch and clamping diode fault diagnosis for Neutral-Point-Clamped inverters is proposed. Multilevel converters employed in safety-critical applications should include fault tolerant capability, where fault diagnosis plays a vital role. The proposed fault diagnosis algorithm is based on failure mode analysis, which is a logic based approach. The required signals and measurements are available in the healthy control system. Furthermore, component modeling, load parameters and complicated calculations are not required. The fault detection and identification of the faulty switch or clamping diode are carried out based on the available data such as switching pattern and terminal voltage. Although switches are more fragile than clamping diodes, clamping diodes are also subjected to breakdown. Hence, it is also crucial to achieve a clamping diode fault diagnosis strategy. Moreover, for fault detection procedure, a voltage quantifier is proposed to avoid any misdiagnosis arising from measurement errors and voltage drop in the circuit. The simulation and experimental results are presented to validate the effectiveness of the proposed approach.

A hybrid five‐level inverter configuration with improved reliability and reduced number of components

“…It is pivotal to detect the fault and identify the failed switch(es) before reconfiguring the circuit and applying the firing signals. Several fault‐detection methods have been proposed in recent years 36,44–48 . The faulty switch is identified based on the missing level in the output voltage.…”

“…Several fault-detection methods have been proposed in recent years. 36,[44][45][46][47][48] The faulty switch is identified based on the missing level in the output voltage. Table 5 depicts the inverter's available and missing voltage levels, and the number of samples sensed at each voltage level in one fundamental cycle at various fault locations.…”

“…The operating mode of the inverter can be identified by sensing its output voltage and current, whether it is healthy or faulty. The detailed fault detection algorithm is discussed in Section 4 36,44–48 . If no fault exists, then apply the switching scheme that corresponds to no fault ( ) as given in Table 2.…”

“…The detailed fault detection algorithm is discussed in Section 4. 36,[44][45][46][47][48] If no fault exists, then apply the switching scheme that corresponds to no fault (F 0 ) as given in Table 2. If fault takes place in any switch, then exclude the switching states that involve the faulty switch and select appropriate switching sequences from the rest of the switching states as given in Table 1.…”

A reliable and efficient modified T‐type fault tolerant five level inverter configuration

“…It emphasizes on the development of a fault‐tolerant mechanism to maintain the rated power even after the fault occurs. The fault detection technique given in References 33,34 has been adopted to detect the switch fault. The faulty switch is identified in CVSU.…”