POWER ELECTRONICS – PAGE 6
Single Phase Bridge Rectifier
1️⃣ Introduction
Bridge rectifier converts both half cycles of AC into pulsating DC using four diodes. It does NOT require a center-tapped transformer.
2️⃣ Circuit Components
- Four diodes (D1, D2, D3, D4)
- Load resistance (R)
- AC input source
3️⃣ Working Principle
Positive Half Cycle
- D1 and D3 conduct
- D2 and D4 are OFF
- Current flows through load in one direction
Negative Half Cycle
- D2 and D4 conduct
- D1 and D3 are OFF
- Current direction through load remains SAME
Important: Output polarity is constant.
4️⃣ Output Characteristics
- Output frequency = 2f
- No negative voltage
- Higher efficiency than half-wave
- No center-tapped transformer required
5️⃣ Important Derivations
Average Output Voltage:
Vavg = (2Vm) / π
RMS Output Voltage:
Vrms = Vm / √2
Ripple Factor:
r = 0.482
Efficiency:
η = 81.2%
6️⃣ Comparison: Center-Tap vs Bridge
| Parameter | Center-Tapped | Bridge |
|---|---|---|
| No. of Diodes | 2 | 4 |
| Transformer | Required | Not Required |
| PIV per Diode | 2Vm | Vm |
| Transformer Utilization | Lower | Higher |
GATE / PSU Focus: PIV calculation, diode conduction sequence, comparison with center-tapped, waveform drawing.
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