A buck converter is to allow an input voltage between 22 V and 40 V, and provides tightly regulated 12 V output. The circuit should use an output capacitor large enough to guarantee +- 1% output ripple at most. The switching frequency is 50 kHz, and the load can range between 10 W and 500 W. Power levels below 200 W are unusual, and inductors are large and costly. It has been suggested that the inductor be chosen so that L >= Lcrit if Pout > 200 W. (a) Draw a circuit diagram that can meet these requirements. What is the range ofduty ratios when Pout > 200 W? (b) What value of inductance will ensure L >= Lcrit for Pout > 200 W? (c) Is it possible to maintain Vout = 12 V at the minimum 10 W load? If so, what duty ratio range will be needed at Pout = 10 W?If not, suggest a way to correct the trouble without changing the value of L.
A buck converter is to allow an input voltage between 22 V and 40 V, and provides
tightly regulated 12 V output. The circuit should use an output capacitor large enough
to guarantee +- 1% output ripple at most. The switching frequency is 50 kHz, and the
load can range between 10 W and 500 W. Power levels below 200 W are unusual, and
inductors are large and costly. It has been suggested that the inductor be chosen so
that L >= Lcrit if Pout > 200 W.
(a) Draw a circuit diagram that can meet these requirements. What is the range ofduty ratios when Pout > 200 W?
(b) What value of inductance will ensure L >= Lcrit for Pout > 200 W?
(c) Is it possible to maintain Vout = 12 V at the minimum 10 W load? If so, what duty ratio range will be needed at Pout = 10 W?If not, suggest a way to correct the trouble without changing the value of L.
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