Introduction

This project implements a microcontroller-based soft starter system for AC motors, designed to reduce inrush current and mechanical stress during motor startup. Using an Arduino Mega controller, the system gradually ramps motor power from 0% to 90% through TRIAC-based AC phase control via the RBD dimmer module. The PZEM-004T power monitor provides real-time voltage and current measurements during the soft-start sequence, displayed on a 20x4 LCD. A 5-stage LED power bar indicator provides visual feedback of the current power level (15%, 30%, 45%, 60%, 75%), and a buzzer signals when full operating power is reached. The system includes safety features such as load detection to verify 220VAC supply presence before starting.

System Overview

Aim and Objectives

Aim:
Design and implement a microcontroller-based AC motor soft starter using TRIAC phase control for gradual power ramping and inrush current reduction.

Objectives:

• Implement gradual motor power ramping from 0% to 90% using RBD AC dimmer with zero-crossing detection.
• Monitor real-time voltage and current during soft-start using PZEM-004T power meter.
• Display motor state (stopped/starting/running), voltage, and current on 20x4 LCD.
• Provide 5-stage LED power bar indicator for visual power level feedback.
• Implement start/stop push button controls with safety interlocks.
• Detect load presence to prevent operation without proper AC supply connection.

Features & Deliverables

• Soft-Start Control: Gradual 0%→90% power ramp via TRIAC AC phase control for reduced inrush current.
• Power Monitoring: PZEM-004T provides real-time voltage and current readings during startup sequence.
• LED Power Bar: Five-stage LED indicator shows power levels at 15%, 30%, 45%, 60%, and 75%.
• LCD Display: 20x4 LCD shows motor state, incremental voltage rise, and current measurements.
• Start/Stop Control: Physical push buttons for motor start and stop with state management.
• Load Detection: Safety check verifies 220VAC supply is connected before allowing start operation.
• Buzzer Indication: Audible signal when motor reaches full operating power.

Process / Methodology

Hardware Assembly

Components: Arduino Mega, PZEM-004T v3.0, RBD AC Dimmer (TRIAC), 20x4 I2C LCD, 5× LEDs, Buzzer, Start/Stop Buttons.

• Connected PZEM-004T power module via Serial2 for voltage and current measurement.
• Configured RBD dimmer module with zero-crossing detection on interrupt pin for phase control.
• Wired 5 LEDs as a sequential power bar indicator across Arduino digital pins.
• Integrated start/stop push buttons with pull-up resistors for motor control.

Software Development

• Developed soft-start algorithm with gradual dimmer power increment from 0% to 90%.
• Implemented voltage mapping during ramp-up to display incremental voltage rise on LCD.
• Programmed 5-stage LED power bar activation at defined power thresholds.
• Added safety logic for load detection and error display when no AC supply is connected.

Testing & Calibration

• Tested soft-start ramp duration and smoothness with various AC motor loads.
• Validated PZEM-004T voltage and current readings against calibrated multimeter.
• Verified load detection reliability under different wiring conditions.

Challenges & Solutions

• Challenge: TRIAC triggering noise causing LCD display interference.
  Solution: Added filtering capacitors and isolated dimmer power lines from logic circuitry.
• Challenge: Precise zero-crossing detection critical for clean phase control.
  Solution: Used RBD dimmer library's built-in zero-crossing detection with interrupt-based timing.
• Challenge: Motor-generated EMI affecting sensor readings during startup.
  Solution: Added averaging and debounce filtering to PZEM-004T readings during ramp-up phase.

Results & Impact

• Inrush Reduction: Soft-start ramp significantly reduced motor inrush current compared to direct-on-line starting.
• Visual Feedback: LED power bar and LCD provided clear indication of startup progress.
• Power Monitoring: Real-time voltage and current data enabled startup performance analysis.
• Safety: Load detection prevented potentially dangerous operation without proper AC connection.

Future Enhancements

• Add configurable ramp time and maximum power settings via user interface.
• Implement overcurrent protection with automatic shutdown.
• Add WiFi connectivity for remote motor control and monitoring.
• Support three-phase motor soft starting with coordinated phase control.

Demonstration / Access

• GitHub Repository: Coming soon
• Live Demonstration Video: Coming soon

Thank You for Visiting My Portfolio

I sincerely appreciate you taking the time to explore my portfolio and learn about my work and expertise. If you have any questions or wish to discuss potential collaborations, please feel free to reach out via the Contact section.

Best regards,
Damilare Lekan, Adekeye.