Bài 8 - Chỉnh lưu có điều khiển hình cầu một pha

Summary

The lesson demonstrates how to model and simulate a single-phase fully controlled bridge rectifier in PSIM. It reviews the thyristor arrangement and conduction sequence, then builds a simulation with a resistive load and a firing angle of 30°.

Circuit principles

• The bridge contains four thyristors arranged in two groups:
  • T1 and T3 form the odd-numbered group, with their cathodes connected together.
  • T2 and T4 form the even-numbered group, with their anodes connected together.
• Two thyristors conduct at a time, one from each group, in diagonal pairs:
  • T1 and T4
  • T2 and T3
• The source may be supplied through a single-phase transformer or, where appropriate, directly from the mains.
• The example uses a purely resistive load. An RL or R–E load can be used if required by an exercise.
• For the example’s 30° firing angle, the average output voltage is approximately 184.7 V.

Simulation procedure

1. Set up the PSIM power circuit with:
   • A single-phase AC source rated at 220 V RMS and 50 Hz
   • A source peak voltage of approximately 311 V
   • Four thyristors in a bridge configuration
   • A 15 Ω resistive load
2. Add measurement blocks to observe the source voltage, load voltage, and load current. Label the measurements clearly and arrange the components neatly.
3. Configure two pulse-generator blocks for the thyristor pairs:
   • Set both generators to 50 Hz.
   • Set the pulse for the T1–T4 pair to begin at 30° and end at 180°.
   • Set the pulse for the T2–T3 pair to begin at 210° and end at 360°.
   • The 180° separation triggers the diagonal pairs in alternate half-cycles.
4. Set the simulation duration to 0.1 seconds, covering five cycles at 50 Hz.
5. Run the simulation and inspect the waveforms. The 30° firing delay should be visible before conduction begins.

Expected results

• Source RMS voltage: approximately 220 V
• Average rectified output voltage: approximately 184.7 V
• Average load current: approximately 12.3 A, consistent with (184.7\text{ V} / 15\ \Omega)

Additional guidance

• Connect the pulse generators to the intended diagonal thyristor pairs. The instructor corrects a pulse assignment during the demonstration.
• The pulse-generation method shown is for a single-phase circuit. Three-phase circuits require a different arrangement, including synchronized blocks, which the instructor says will be covered in a later lesson.

Speakers and sources

• Speaker: One instructor narrates the explanation and PSIM demonstration.
• Sources and materials: A single-phase controlled bridge rectifier schematic and the PSIM simulation environment. No other speakers are identifiable.