GATE 2000 Electrical Engineering PYQ

Question

A step down chopper operates from a $$dc$$ voltage source $${V_s}$$ feeds a $$dc$$ motor armature with a back $$e.m.f$$ $$\,\,{E_b}.$$ From oscilloscope traces, it is found that the current increases for time $${t_r}$$ falls to zero over time $${t_f},$$ and remains zero for time $${t_0}$$ in every chopping cycle, then the average $$dc$$ voltage across the freewheeling diode is

GATE 2000 organizing institute · Accepted Answer

$${{\left( {{V_s}\,{t_r} + {E_b}\,{t_0}} \right)} \over {\left( {{t_r} + {t_f} + {t_0}} \right)}}$$

GATE 2000 organizing institute · Answer

$${{{V_s}\,{t_r}} \over {\left( {{t_r} + {t_f} + {t_0}} \right)}}$$

GATE 2000 organizing institute · Answer

$${{\left( {{V_s}\,{t_r} + {E_b}\,{t_f}} \right)} \over {\left( {{t_r} + {t_f} + {t_0}} \right)}}$$

GATE 2000 organizing institute · Answer

$${{{V_s}\,{t_r} + {E_b}\left[ {{t_f} + {t_0}} \right]} \over {\left( {{t_r} + {t_f} + {t_0}} \right)}}$$