Shoot-through mode

An interesting feature of the Z-source DC circuit breaker is its ability to automatically respond to a short-circuit fault in its DC load and to protect the power source from the fault. A Z-source circuit breaker between a power source and an inverter (Fig. 8.47) allows to simultaneously close the upper and the lower power switch of an inverter phase leg. The combination of a Z-source circuit and an inverter is known as Z-source inverter (ZSI). If both switches of a phase leg are on, the inverter is said to be in shoot-through mode. That is, the Z-source inverter has another mode in addition to the six active modes and the two null modes of a traditional 3-phase inverter. 

Simulation runs have used the parameters in Table 8.7. Parameter values have been chosen so that the resonance in shoot-through mode is visible. An ode-solver with a root finding capability has been used to detect the time point at which the SCR current becomes zero. 

Figure8.50a displays that, in shoot-through mode, the sum of currents il, + ici - iD-i in fact vanishes, i.e. the DC voltage source is isolated from the fault. In the faultless case, the steady state current flows through the SCR, the inductors and the load resistor. If the resistances of the inductors are neglected then the load...

Another way of reducing the reverse recovery current shoot-through is simply to ensure that the boost diode is carrying no forward current at the moment when the switch starts to turn ON. The diode then blocks reverse voltage instantly. In other words, running the Boost in DCM or BCM (boundary conduction mode, i.e., at the critical boundary) will produce higher peak currents, but smaller inductors (yes, if r is large, the size of any inductor typically reduces ), and perhaps much better efficiency too, because now, the turn-on crossover loss becomes zero. 

Cell Division Inhibitors. The most common mode of action of soil-appHed herbicides is growth inhibition, primarily through dkect or indkect interference with cell division (163). Such growth inhibitory activity is the basis for most pre- or post-emergent herbicides intended to control germinating weed seeds. In germinating seeds, cell division occurs in the meristems of the root and the shoot. Meristematic cells go through a cycle... 

Failure Mode and Effects Analysis Another method is failure mode and effects analysis. It considers what may go wrong and what the consequences will be. Most people are familiar with this method through diagnostic charts that aid in trouble shooting automobiles or other equipment. By locating the failure or symptom in the chart, one can locate possible causes and solutions for the problem. In failure mode and effects analysis for safety, one is trying to identify what controls will prevent or reduce the danger of some hazard. 

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