RAMKRISHNA MAHATO GOVERNMENT ENGINEERING COLLEGE , PURULIA.pptx

POWER ELECTRONICS ,UNCONTROLLED RECTIFIER

1. RAMKRISHNA MAHATO GOVERNMENT ENGINEERING COLLEGE , PURULIA

2. Title: Uncontrolled Rectifiers Subtitle: Understanding the Basics

3. Uncontrolled Rectifiers Overview Definition: Uncontrolled rectifiers use diodes as the rectifying elements, which cannot control the output voltage once the AC input is applied. Simple Construction: Diodes: The key component in an uncontrolled rectifier is the diode, which only allows current to flow in one direction. Basic Circuit: The circuit is straightforward, typically involving just a few diodes and possibly a transformer, depending on the rectifier type (e.g., half-wave, full-wave).

4. No External Control Fixed Output: The output voltage and current are determined solely by the input AC signal and the components used. No Adjustments: Unlike controlled rectifiers, there are no additional components (like thyristors) to regulate or control the output. Once the circuit is built, the output is fixed.

5. Fixed Output Voltage and Current: No External Control: The output voltage and current are fixed and directly determined by the input AC signal and the circuit design. Constant Output: Unlike controlled rectifiers, there is no mechanism to adjust the output, making the DC voltage and current constant.

6. Types of Uncontrolled Rectifiers Half-Wave Rectifier Full-Wave Rectifier Center-tapped Full-Wave Rectifier Bridge Rectifier

7. Half-Wave Rectifier Formula: Circuit Diagram:

8. Working Principle: Only one half-cycle of the AC input is used. The diode conducts during the positive half-cycle and bocks the negative half-cycle. Waveform Diagram

9. Full-Wave Rectifier Formula: Circuit Diagram:

10. Working Principle: Both half-cycles of the AC input are used. The diodes alternate to provide continuous output. Waveform Diagram:

11. Center -Tapped Full-Wave Rectifier Explanation: Uses a center-tapped transformer. Two diodes are used, each conducting during alternate half-cycles. Waveform Diagram Circuit Diagram

12. Bridge Rectifier Explanation: Four diodes are used. No center-tapped transformer is needed. Circuit Diagram Waveform Diagram

13. 3-Phase Bridge Rectifier Introduction: A 3-phase bridge rectifier converts three-phase AC into DC. It uses six diodes arranged in a bridge configuration. Circuit Diagram: Working Principle: Diode Pairs: At any given moment, two diodes conduct—one from the positive group and one from the negative group—providing Continuous DC output. Phases: Each phase of the AC supply contributes to the DC output, ensuring that the voltage never drops to zero.