Low cost speed control for single phase induction motors - comparing different approaches with regard to efficiency

Operating single phase fed motors across a wide range of speed and load single phase fed motors across a wide range of speed and load with high efficiency is of growing interest. The paper at hand presents an investigation into the efficiency of different low cost variable speed drive concepts (namely phase control, integral (half) cycle control and integral switched cycle control) based on capacitor run single phase induction motors. Simulations and measurements concerning for example the efficiency achieved and the speed-torque characteristics of the different concepts are presented. Subsequently, ideas for improvements (selecting a different run capacitor, lowering the inrush current and the amplitude of the fundamental component by combining phase control with integral switched cycle control) are put forward.