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Q83HardChoppers (DC-DC Converters)

એક DC-DC બૂસ્ટ કન્વર્ટરમાં Vin = 10 V, L = 100 μH, f = 50 kHz છે. તે Vo = 25 V પર 25 W આપે છે. ચકાસો
1. ડ્યૂટી સાઇકલ D = 0.6 છે.
2. પીક-ટુ-પીક પ્રેરક પ્રવાહ રિપલ 1.2 A છે.
3. સરેરાશ પ્રેરક પ્રવાહ 2.5 A છે.
કયાં વિધાનો સાચાં છે?

જવાબ અને પગલાવાર ઉકેલ
સાચો જવાબ: C. 1, 2 અને 3
ટૂંકી સમજૂતી

C — 1, 2 અને 3. D = 1 − Vin/Vo = 1 − 10/25 = 0.6; ΔIL = Vin·D/(L·f) = 10×0.6/(100 μH × 50 kHz) = 1.2 A; સરેરાશ પ્રેરક (ઇનપુટ) પ્રવાહ = P/Vin = 25/10 = 2.5 A.

વિગતવાર ઉકેલ (મૂળ ભાષામાં)

Statement-wise Verification

  • Statement 1 - Correct.
    The duty cycle D is 0.6.
    D=1−Vin/Vo=1−10/25=0.6. ΔIL=VinD/(Lf)=10×0.6/(100 μH×50 kHz)=1.2 A.
  • Statement 2 - Correct.
    The peak-to-peak inductor current ripple is 1.2 A.
    Ideal average input/inductor current=P/Vin=25/10=2.5 A.
  • Statement 3 - Correct.
    The average inductor current is 2.5 A.
    Ideal average input/inductor current=P/Vin=25/10=2.5 A.

Core Concept

An ideal boost converter in continuous conduction has an output voltage greater than or equal to input for 0≤D<1. When the switch is off, it must block approximately the output voltage. The output capacitor supplies load current between energy-transfer intervals and reduces output ripple.

Formula / Key Relationship

V_o=V_in/(1−D); ΔI_L≈V_in D/(Lf_s).

Step-by-Step Check

D=1−Vin/Vo=1−10/25=0.6. ΔIL=VinD/(Lf)=10×0.6/(100 μH×50 kHz)=1.2 A. Ideal average input/inductor current=P/Vin=25/10=2.5 A.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 3. Option B is incorrect because it omits correct statement(s) 1. Option D is incorrect because it omits correct statement(s) 2.

Exam Shortcut / Approach

For an ideal boost, D=1−Vin/Vo.

Common Mistake

A normal boost converter cannot produce Vo<Vin merely because D<0.5.

Quick Revision

Duty Ratio Inductor Ripple and Input Current is linked with Boost Converter, DC-DC Converters and Power Electronics. For an ideal boost, D=1−Vin/Vo.

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