A forced commutated thyristorized step-down chopper is shown in the figure. Neglect the ON-state drop across the power devices. Assume that the capacitor is initially charged to 50 V with the polarity shown in the figure. The load current  can be assumed to be constant at 10 A. Initially,  is  and  is OFF. The turn-off time available to  in microseconds, when  is triggered, is _______ (rounded off to the nearest integer).

A voltage commutated chopper circuit, operated at 500Hz, is shown below

If the maximum value of load current is 10A, then the maximum current through the main (M) and auxiliary (A) thyristor will be

In the chopper circuit shown, the main thyristor  is operated at a duty ratio of 0.8 which is much larger the commutation interval. If the maximum allowable reapplied dv/dt on  is , what should be the theoretical minimum value of ? Assume current ripple through  to be negligible.

A voltage commutated chopper operating at 1 kHz is used to control the speed of dc motor as shown in figure.  The load current is assumed to be constant at 10 A.

The minimum time in µsec for which the SCR M should be ON is 

A voltage commutated chopper operating at 1 kHz is used to control the speed of dc motor as shown in figure.  The load current is assumed to be constant at 10 A.

The average output voltage of the chopper will be 

Figure shows a chopper. The device S1 is the main switching device. S2 is the auxiliary commutation device. S1 is rated for 400V, 60A. S2 is rated for 400V, 30 A. the load current is 20 A. The main device operates with a duty ratio of 0.5.  The peak current through S1 is

A voltage commutated thyristor chopper circuit is shown in figure.  The chopper is operated at 500 Hz with 50% duty ratio.  The load takes a constant current of 20A.

(a) Evaluate the circuit turn off time for the main thyristor .

(b) Calculate the value of inductor L, if the peak current through the main thyristor  is limited to 180% of the load current.

(c) Calculate the maximum instantaneous output voltage of the chopper.

In a thyristor dc chopper, which type of commutation results in best performance?

Consider the chopper circuit of figure. The chopper operates at 400Hz and 50% duty cycle. The load current remains almost ripple free at 10A. Assuming the input voltage to be 200V and the devices to be ideal, the turn-off time available to the thyristor ThM is ____ μs.