Quick Diagnosis of Short Circuit Faults in Cascaded H-Bridge Multilevel Inverters using FPGA

Abstract

Fast and accurate fault detection is the primary step and one of the most important tasks in fault tolerant converters. In this paper, a fast and simple method is proposed to detect and diagnosis the faulty cell in a cascaded H-bridge multilevel inverter under a short circuit fault. In this method, the reference voltage is calculated using switching control pulses and DC-Link voltages. The comparison result of the output voltage and the reference voltage is used in conjunction with active cell pulses to detect the faulty cell. To achieve this goal, the cell which is active when the Fault signal turns to "0" is detected as the faulty cell. Furthermore, consideration of generating the active cell pulses is completely described. Since the main advantage of this method is its simplicity, it can be easily implemented in a programmable digital device. Experimental results obtained with an 11-level inverter prototype confirm the effectiveness of the proposed fault detection technique. In addition, they show that the diagnosis method is unaffected by variations of the modulation index.

Modified Space Vector Modulation for Cascaded H-Bridge Multilevel Inverter with Open-Circuit Power Cells

“…e output voltage of cell x is measured; it can be −V dc ; 0; V dc •V out_cellx then will be passed into standardized block and compared with a given threshold (TH) and finally changed into logic signal: In fact, V dc can fluctuate; the TH value must be calculated carefully to compensate for this tolerance to make the standardized signal accurate. erefore, V dc /2 is the appropriate value for TH threshold [20].…”

Superconducting currents and charge gradients in the octonion spaces

“…In case either the electromagnetic strength or gravitational strength is strong enough, the field strength has an influence on the current derivatives and charge gradients to a certain extent, according to the second-force equilibrium equation, Eq. (11). Further the derivatives, ∂ t B , ∂ t E , ∂ t g , and ∂ t b and others are strong enough sometimes, they will exert an impact on the superconducting currents within the conductors, according to the second-force equilibrium equation, Eq.…”

“…In the practical engineering application, the scholars and engineers have spent lots of time and endeavor on the item, introducing a variety of methods to resist the threat of the high pulse electric-current and its current derivative. The application scope of the current derivative is very expansive, mainly involving the electronic control system [8], direct-current (DC for short) electromotor [9], DC traction power supply system [10], quick short-circuit protection circuits [11], DC power changing set of silicon controlled rectifier [12], automatic speed regulator [13], reversible speed control system [14], current-limiting fuse [15], vacuum evaporation equipment [16], CMOS and IGBT Modules [17,18] and others.…”