Performance analysis of single phase fully controlled bridge converter with R and R-L load.

Experiment No. 03

Title of the Experiment: –

Performance analysis of single phase fully controlled bridge converter with R and R-L load.

Objectives: –

To be written by student.

Apparatus Required: –

  1. MATLAB installed in a computer system.

Simulation Parameters: –

  1. Parameters for Resistive Load (R):
    • Source Magnitude (Vs) = 100 V
    • Frequency (f) = 50 Hz
    • Pulse of thyristor 1 and 3 = 300 and 600 = 0.00167 s and 0.00333 s
    • Pulse of thyristor 2 and 4 = 2100 and 2400 = 0.01167 s and 0.01333 s
    • Resistance = 100 ohm.

Block Model for Resistive (R) Load: –

Theory: –

A single phase fully controlled bridge rectifier is a power electronics converter that converts single-phase AC supply into variable DC output voltage using thyristors (SCRs) arranged in a bridge configuration. The output DC voltage is controlled by varying the firing angle (α) of the SCRs.

Circuit Description:

  • The circuit consists of four SCRs( T1, T2, T3. T4 ) connected in a bridge.
  • An AC supply is connected to the bridge input.
  • A load (R or R-L) is connected across the DC output terminals.
  • Gate pulses are applied to the SCRs to control their turn-on instant.

Working Principle:

Positive Half Cycle (0 to π)

  • During the positive half cycle of the AC supply:
    • SCR T1 and T2 are forward biased.
    • They are Triggered at a firing angle α.
    • Current flows through: Source–> T1 –> Load–> T2 –> Source
    • The load receives a positive voltage.

Negative Half Cycle (Ď€ to 2Ď€)

  • During the negative half cycle of the AC supply:
    • SCR T3 and T4 are forward biased.
    • They are Triggered at a firing angle Ď€+α.
    • Current flows through: Source–> T3 –> Load–> T4 –> Source
    • The voltage polarity remains the same.

So, full-wave rectification is achieved.

Control of Output Voltage:

  • The output voltage depends on the firing angel α.
  • By increasing α, the average output voltage decreases.
  • When α > 900, the average output voltage becomes negative, allowing inverter operation.
\[\color\Green{Let,}\] \[\color\red{V_m\;}\color\magenta{ =}\color\green{Peak\;value\;of\;AC\;supply\;voltage}\] \[\color\red{\alpha}\;\color\magenta{=}\;\color\green{Firing\;angle}\]
\[\color\green{Average\;output\;voltage\;(R\;Load}\] \[\color\red{V_{dc}}\;\color\magenta{=}\;\color\red{\dfrac{2V_m}{\pi}cos\alpha}\] \[\color\green{Maximum \;output\; at\; \alpha \;= \;0^0}\] \[\color\green{Zero \;output\; at\; \alpha\; =\; 90^0}\]

Experimental Setup: –

Output Waveforms: –

Resistive Load (R) with 300 Phase Delay
Resistive Load (R) with 600 Phase Delay

Simulation Parameters: –

2. Parameters for Resistive – Inductive ( R – L) Load:

  • Source Magnitude (Vs) = 100 V
  • Frequency (f) = 50 Hz
  • Pulse of thyristor 1 and 3 = 300 and 600 = 0.00167 s and 0.00333 s
  • Pulse of thyristor 2 and 4 = 2100 and 2400 = 0.01167 s and 0.01333 s
  • Resistance = 10 ohm.
  • Inductance = 0.04 H

Block Model for Resistive – Inductive (R-L) Load: –

Output Waveforms: –

Resistive – Inductive Load (R-L) with 300 Phase Delay
Resistive – Inductive Load (R-L) with 600 Phase Delay

Simulation Parameters: –

3. Parameters for Resistive – Inductive ( R – L) Load with freewheeling diode:

  • Source Magnitude (Vs) = 100 V
  • Frequency (f) = 50 Hz
  • Pulse of thyristor 1 and 3 = 300 and 450 = 0.00167 s and 0.0125 s
  • Pulse of thyristor 2 and 4 = 2100 and 2250 = 0.01167 s and 0.0125 s
  • Resistance = 10 ohm.
  • Inductance = 0.04 H
  • Freewheeling Diode: Resistance = 0.001 Ohm, Forward Voltage = 0.8 Volts.

Block Model for Resistive – Inductive ( R – L) Load with freewheeling diode : –

Output Waveforms: –

Resistive – Inductive Load (R-L) with free wheeling diode for 300 Phase Delay
Resistive – Inductive Load (R-L) with free wheeling diode for 450 Phase Delay

Conclusion : –

To be written by student.

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