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:

Hardware Required:

Arduino board – ATmega328P datasheet
2 x Thyristor (SCR). I used TYN1225 —> datasheet
2 x optocoupler. I used PC817 —> datasheet
LM393 (or LM339) comparator —> datasheet
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.

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.

// Controlled bridge rectifier with Arduino

#define scr1_gate   8
#define scr2_gate   9
#define pot        A0

byte ZC = 0;
uint16_t alpha;
void setup(void) {
  pinMode(scr1_gate, OUTPUT);
  digitalWrite(scr1_gate, LOW);
  pinMode(scr2_gate, OUTPUT);
  digitalWrite(scr2_gate, LOW);
  attachInterrupt(0, ZC_detect, CHANGE);       // Enable external interrupt (INT0)
}

void ZC_detect() {
  if(digitalRead(2))
    ZC = 1;
  else
    ZC = 2;
}
void loop() {
  if(ZC == 1){
    delayMicroseconds(alpha);
    digitalWrite(scr1_gate, HIGH);
    delay(2);
    digitalWrite(scr1_gate, LOW);
    alpha = analogRead(pot) * 7;
    ZC = 0;
  }
  if(ZC == 2){
    delayMicroseconds(alpha);
    digitalWrite(scr2_gate, HIGH);
    delay(2);
    digitalWrite(scr2_gate, LOW);
    alpha = analogRead(pot) * 7;
    ZC = 0;
  }
}

// Controlled bridge rectifier with Arduino

#define scr1_gate 8

#define scr2_gate 9

#define pot A0

byte ZC = 0;

uint16_t alpha;

void setup(void) {

pinMode(scr1_gate, OUTPUT);

digitalWrite(scr1_gate, LOW);

pinMode(scr2_gate, OUTPUT);

digitalWrite(scr2_gate, LOW);

attachInterrupt(0, ZC_detect, CHANGE); // Enable external interrupt (INT0)

}

void ZC_detect() {

if(digitalRead(2))

ZC = 1;

else

ZC = 2;

}

void loop() {

if(ZC == 1){

delayMicroseconds(alpha);

digitalWrite(scr1_gate, HIGH);

delay(2);

digitalWrite(scr1_gate, LOW);

alpha = analogRead(pot) * 7;

ZC = 0;

}

if(ZC == 2){

delayMicroseconds(alpha);

digitalWrite(scr2_gate, HIGH);

delay(2);

digitalWrite(scr2_gate, LOW);

alpha = analogRead(pot) * 7;

ZC = 0;

}

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

Reference:
Power Electronics Handbook – MUHAMMAD H. RASHID

Anish

February 19, 2024 at 4:24 pm

Hello Can i get this proteus simulation.

Shivansh

May 1, 2022 at 7:52 am

Can anyone help me about this project?

Douglas R Henderson

February 23, 2021 at 9:32 am

Any changes needed to use this with 120 VAC, other than the step down transformer?
I’m looking to control it remotely, wirelessly, can I use a PWM output pin to control it instead of a manual 10K pot?
Thanks, DougRH

Douglas R Henderson
February 23, 2021 at 10:46 am
I’m looking for speed control of 120 VAC motors. Would this work with brushless, induction motors as well as brushed motors?
&/or an Analog output pin as well as a PWM digital IO pin on an Arduino?

José L. Ureño

December 30, 2019 at 9:57 pm

I need A similar circuit to run on 120 volts, with out the step down transformer.
Can some anybody help me, has anyone done that before, this circuit is good, but is not what I need and I won’t know how to modify it my self.