Controlled bridge rectifier with Arduino

Last time I made a simple half-wave controlled rectifier using Arduino and thyristor (SCR), and in this topic shows how did I built a full-wave bridge rectifier using Arduino (half-controlled bridge rectifier).

Previous project link is the one below:
SCR control with Arduino – Half-wave controlled rectifier

The figure below shows the half-controlled bridge rectifier, which uses two thyristors and two diodes:

half-controlled bridge rectifier

Hardware Required:

  • Arduino board
  • 2 x Thyristor (SCR). I used TYN1225 – datasheet
  • 2 x optocoupler. I used PC817 – datasheet
  • LM393 (or LM339) comparator
  • 6 x IN4007 diode
  • 10k ohm resistor
  • 10k ohm potentiometer
  • 4 x 1k ohm resistor
  • Resistive load. I used 270 ohm resistor
  • 2 x 220 ohm resistor
  • 220V to 12V step down transformer
  • Breadboard
  • Jumper wires

Controlled bridge rectifier with Arduino circuit:
Project circuit schematic diagram is shown below.

arduino controlled bridge rectifier with thyristors

All grounded terminals are connected together.

The rectifier bridge consists of two thyristors T1, T2 and two diodes D1 , D2 (half controlled bridge rectifier). The transformer is used to step down the 220V into 12V.

In the circuit there are two optocouplers, each one is used to fire one thyristor (give current to the gate of the thyristor), thyristor T1 is fired with Arduino pin 8 and thyristor T2 is fired with arduino pin 9.

In this example I used the LM393 (dual comparator IC) for the zero crossing detection, an optocoupler can be used for the same purpose but I think the comparator is better. The two diodes which are connected between the non-inverting input (+) and the inverting input (-) of the comparator are used to limit the voltage across those pins (the LM393 can work directly with 12V, so they are optional). The output of the LM393 (or LM339) is an open collector, so I added the 10k ohm resistor there (between +5V and arduino pin 2). Also the comparator chip is supplied with +5V which comes from the Arduino board.

In this example I used a resistive load with resistance of 270 ohm

The 10k ohm potentiometer is used to control firing angle.

Arduino code:
Full Arduino code is below.

The following video shows output waveform and the variation of the firing angle:

Reference:
Power Electronics Handbook –┬áMUHAMMAD H. RASHID

3 comments

  1. I am not able to control the alpha with potentiometer. The code is same as yours, still my alpha is not changed. Please help me out through this.

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