An R-L load is connected to a 250 V, 400 Hz step down dc converter. The average load current is 100 A...
RL Circuit Inductor Calculation
Given Data
- Supply voltage V = 250 V
- Frequency f = 400 Hz
- Load current IDC = 100 A
- Load resistance R = 0.5 Ω
- Allowed ripple = 15%
Step 1: Ripple Current
Iripple = 0.15 × 100 = 15 A
Step 2: Ripple Voltage
Approximation:
Vr ≈ 250 V
Step 3: RL Ripple Formula
Iripple = Vr / √(R² + (ωL)²)
Rearranging:
√(R² + (ωL)²) = Vr / Iripple
R² + (ωL)² = (250 / 15)²
Step 4: Solve
250 / 15 = 16.67
R² = (0.5)² = 0.25
(ωL)² = 16.67² − 0.25
(ωL)² ≈ 277.8 − 0.25 = 277.55
ωL ≈ √277.55 ≈ 16.66
Step 5: Find Inductance
ω = 2Ï€f = 2Ï€ × 400 ≈ 2513
L = 16.66 / 2513
L ≈ 0.00663 H
Final Answer
L ≈ 6.6 mH
option B
- High frequency → smaller inductance needed
- Low resistance → inductor dominates ripple control
- 15% ripple → moderate inductance value