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# 01 - 3-The thyristor in the shown circuit has a latching...

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Faculty of Information Engineering & Technology Electrical & Electronics Department Course: Power Electronics (ELCT 704) Problem Set- 2 Sheet (1) 1-The data sheet of a switching device specify the following switching times corresponding to the linear characteristics shown in figure for this inductive switching: t ri =100ns, t fv =50ns, t rv =100ns, t f i=200ns. Calculate and plot the switching power loss as a function of time, assuming that V d =300V and I o =4A in the circuit shown in figure. 2-For the same circuit of the previous problem, If V d =40V ,I o =5A, D=0.4 and f=300KHz.Assume that the switching times t on =t off =25ns. The on state resistance R=0.3ohms.Calculate the power losses and the converter efficiency.

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Unformatted text preview: 3-The thyristor in the shown circuit has a latching current level of 50mA and is fired by a pulse of length 50 microseconds. Show that without resistance R the thyristor will fail to remain on when the firing pulse ends, and then find the maximum value of R to ensure firing. Neglect the voltage drop. R L =20Ω, L=0.5H. 4- A thyristor has a forward characteristic which may be approximated over its normal working range to the straight line shown in figure. Estimate the mean power loss for: a. A continuous on-state current of 23A b. A half sine wave of mean value 18 A c. A level current of 48.5 A for one-third cycle...
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