ESP32 AC Motor Speed Controller

Real-time AC motor speed control using phase-angle modulation with TRIAC and zero-crossing detection on ESP32.

Description

This project implements a real-time speed controller for AC motors using an ESP32 development board and a TRIAC-based power control circuit. Motor speed is regulated by adjusting the TRIAC firing angle, which is controlled via serial commands. A zero-crossing detector circuit ensures precise synchronization with the AC waveform for stable operation.

Features

• Real-Time Speed Adjustment: Modify motor speed by sending commands through the serial monitor
• Phase-Angle Control: Digital technique for regulating power delivered to the motor
• Zero-Crossing Detection: Precise synchronization with AC signal for stable control
• Serial Interface: Easy control via UART commands (0-180 degrees)

Hardware Requirements

• ESP32 Development Board
• TRIAC-based power control circuit
• Zero-crossing detection circuit (connected to GPIO 17)
• TRIAC gate control (connected to GPIO 16)
• AC motor (compatible with TRIAC control)

Software

• Platform: Arduino IDE / PlatformIO
• Language: C++ (Arduino framework)
• Baud Rate: 115200

Pin Configuration

Function	GPIO Pin
TRIAC Gate	16
Zero-Crossing Input	17

Installation

1. Hardware Assembly: Connect the TRIAC power circuit and zero-crossing detector to the ESP32 as specified in the pin configuration
2. Load Firmware: Upload ac_motor_control.ino to your ESP32 using Arduino IDE
3. Open Serial Monitor: Start serial communication at 115200 baud
4. Send Commands: Control motor speed by sending a numeric value between 0 and 180 (representing firing angle in degrees)
5. Observe Results: Motor adjusts speed dynamically based on the firing angle

Usage

Serial Commands

Send a value between 0-180 followed by a newline:

0    # Minimum speed
90   # Medium speed
180  # Maximum speed

Example Code Snippet

void loop() {
  if (Serial.available() > 0) {
    int angle = Serial.parseInt();
    if (angle >= 0 && angle <= 180) {
      firingAngle = angle;
      Serial.print("Firing angle set to: ");
      Serial.println(firingAngle);
    }
  }
}

How It Works

The main program continuously monitors the zero-crossing detector signal. When a zero-crossing is detected, it calculates a delay based on the firingAngle and, after that time elapses, sends a short pulse to the TRIAC gate to activate it. Commands to update the angle are received asynchronously through the serial port.

Phase-Angle Control Principle

1. Detect AC zero-crossing
2. Wait for calculated delay (based on firing angle)
3. Send trigger pulse to TRIAC gate
4. TRIAC conducts for remainder of half-cycle
5. Repeat for each AC cycle

Circuit Diagram

AC Line ──┬─── TRIAC ─── Motor
          │
          └─── Zero-Crossing Detector ──► GPIO 17
                          │
                     TRIAC Gate ◄──── GPIO 16 (ESP32)

Safety Warning

⚠️ This project involves working with AC mains voltage. Only attempt if you have proper knowledge of electrical safety. Use proper isolation and protection circuits.

Applications

• Variable speed fans
• Light dimmers
• Pump speed control
• Industrial motor controllers
• Power tools

License

This project is licensed under the MIT License. See the LICENSE file for details.

Authors

Rafael Gonzalez

• GitHub: @surbalo1
• LinkedIn: Rafael Gonzalez

Jaime Joel Olivas Muñoz

• Collaborator