V1I5P13

An Efficient Asymmetrical PWM Technique for Speed Control of Single-Phase Induction Motors in Low-power applications

Chokshi bhargav¹*, Vasimmahamad Ghanchi², Romi Kantharia³, Sarfaraj  Gandhi⁴, Nirpex rana⁵

Abstract

Single phase induction motors (SPIMs) are widely used in home appliances and small-scale industrial applications due to their simplicity and ruggedness. However, conventional speed control techniques, such as phase angle control using TRIACs, suffer from high harmonic distortion and poor efficiency. In recent years, adjustable speed induction motor drives have been enhanced using advanced pulse width modulation (PWM) strategies to improve performance. This paper presents an AC Pulse Width Modulation (ACPWM) control system implemented with an AVR microcontroller to regulate the effective applied voltage of a single-phase induction motor using an AC chopper and TRIAC switching. An asymmetrical PWM technique synchronized using a zero-crossing detector (ZCD) is employed to reduce the harmonic content in motor current and improve efficiency. MATLAB/SIMULINK simulations are performed under normal and hysteresis PWM strategies to validate performance improvements. A hardware prototype using an AVR controller and MOC3021 opto-isolator to trigger the TRIAC is developed and tested. Experimental results demonstrate that the proposed method yields smoother control, lower total harmonic distortion (THD), and better speed regulation compared to traditional phase-angle controlled drives.

Keywords:

AC PWM, Single Phase Induction Motor, Asymmetrical PWM, Zero Crossing Detector, AVR Microcontroller, Harmonic Reduction