Theoretical Analysis and Experimental Validation of Flying-Capacitor Multilevel Converters Under Short-Circuit Fault Conditions

Abstract

Addressing the increasing demand for highefficiency and high-power-density converters, the flying-capacitor multilevel converter has shown itself as a promising topology. A key advantage of this topology is the reduced voltage rating of the switches, which also makes it vulnerable to device failure during short-circuit conditions. Despite a large interest in fault-tolerant operation of these converters alongside detailed descriptions of flying capacitor balancing during different conditions, little research has focused on the converter short-circuit fault analysis, which may cause a switch failure if not properly designed for. To address this vulnerability, this work presents a comprehensive model describing the large-signal short-circuit switching behavior of a general N -level flying-capacitor multilevel converter. Based on this, highly simplified models used to predict the evolution of the switch current and voltage stress during the fault are proposed, targeted at practicing engineers for conservative design guidelines. These models are used to determine the time for remedial action of the converter before reaching some predefined maximum tolerable conditions. A 2-to-10-level fully-configurable flying-capacitor multilevel converter and a fault circuit hardware prototype are used to experimentally perform different shortcircuit tests, which shows a good match between the predicted and measured behavior.

Reliability Analysis of a Multilevel Inverter Applied to Stratospheric Drones Using Fault Tree Analysis

“…However, as the number of levels increases, the control becomes more complicated, switching losses increase, and a large number of capacitors are required. The number of switching required to make the m-level is 2 (m−1), the number of capacitors of the direct current link is (m−1), and the number of flying capacitors is (m−1) (m−2)/2 [33][34][35]. Figure 2 shows the operation mode of the FCC topology, which is analyzed by dividing it into voltage and the current directions, zero-level, and 1-level.…”

DC active power filter based on model predictive control for DC bus overvoltage suppression of accelerator grid power supply

“…A large number of capacitors will reduce the overall reliability of the power supply. Finally, if the DC bus is short-circuited, the capacitor will also produce a huge surge current, resulting in devastating consequences [9].…”

Model Predictive Current Control of Multilevel Smart Load Based on MPUC7 Converter

“…Nonetheless, in this work, a full-bridge inverter topology is employed as ES1 that still has poor power quality performance. Flying capacitor (FC) [19], cascaded H-bridge (CHB) [20] or active-neutral-point-clamped (ANPC) [21], as well-established multilevel converters, can be also developed for ES1 applications. As an instance, in [21] an ANPC converter is introduced for multilevel electric spring applications.…”