Page 33 – Source Inductance & Overlap Angle (GATE Advanced)
Subject: Power Electronics
Topic: Overlap Angle (μ) in Fully Controlled Rectifier
Level: GATE / PSU High Level
🔹 Why Overlap Occurs?
Due to source inductance (Ls), current cannot transfer instantly from outgoing SCR pair to incoming SCR pair.
- Both SCR pairs conduct simultaneously
- This interval is called Overlap Angle (μ)
- Output voltage reduces
🔹 Effect on Output Voltage
Ideal Case (No overlap):
Vavg = (2Vm/π) cos α
With Overlap:
Vavg = (2Vm/π) cos α − (ωLsId)
ω = 2πf
Id = Load current
🔹 Overlap Angle Formula
μ = (ωLsId) / Vm
Overlap increases when:- Source inductance increases
- Load current increases
- Supply voltage decreases
🔹 Important GATE Observations
- Overlap reduces DC output voltage
- Power factor decreases
- Commutation becomes slower
- In high current systems μ becomes significant
🔹 Numerical Example
Given:
Ls = 3 mH
Id = 20 A
f = 50 Hz
Vm = 325 V
ω = 2π × 50 = 314 rad/s
μ = (314 × 0.003 × 20) / 325
μ = (18.84) / 325 = 0.058 rad
= 3.3°
Quick Revision
Overlap Angle μ reduces output voltage.
Vavg = Ideal − (ωLsId)
Advanced Power Electronics – Shaktimatha Learning
.png)
No comments:
Post a Comment