In DC chopper, per unit ripple is maximum when duty cycle α is
In DC chopper, per unit ripple is maximum when duty cycle α is
Right Answer is:
0.5
SOLUTION
The Per unit ripple of DC Chopper is given as
Where
D = Duty Cycle = Ton/T
T = Chopping period
τ = Time constant = L/R
The ripple current is maximum if the differentiation of the above equation with respect to D is equal to zero.
Hence the ripple in load current is maximum when duty cycle D = 0.5 as shown in Fig.
For duty cycle at= 50% (i.e. α= 0.5) and T/τ= 5, per unit ripple current become 0.848. Similarly for a= 0.5 and T/τ = 25, per unit ripple current = 1. In this way, the variation of per unit ripple current as a function of duty cycle α and T/τ can be plotted.