Load-Adaptive Efficiency Enhancement in Capacitor-Start Single-Phase Induction Motors Using Optimized Capacitance Control: An Experimental Study

Abstract

This paper presents an experimental investigation of efficiency enhancement in capacitor-start single-phase induction motors (CS-SPIMs) using a load-adaptive capacitance control technique. Conventional motors employ fixed capacitors optimized for rated conditions, resulting in degraded efficiency and poor power factor under partial load operation. The proposed system utilises a switched capacitor bank controlled by a microcontroller to dynamically adjust capacitance based on real-time operating conditions. Voltage and current signals are measured and processed to estimate the power factor using a zero-crossing detection method, enabling the controller to select the optimal capacitor configuration that maximises performance. A hysteresis-based switching mechanism is incorporated to ensure stable operation and prevent excessive switching. Experimental results demonstrate that the adaptive system improves efficiency by up to 15.6% at light load conditions, while significantly enhancing power factor across the entire load range. Repeatability tests and uncertainty analysis are also conducted to validate the reliability and consistency of the measurements. The proposed approach provides a simple, low-cost, and effective alternative to complex power electronic solutions, making it particularly suitable for practical and resource-constrained applications.