A Method of Variable Frequency and Variable Speed Control for Single-Phase Capacitor Motors

Based on the structural features of single-phase capacitor motors and on the principle of using space vector ofmagnetic fluxto approach the rotating round magnetic field in the motors, a new method of variable frequency and variable speed control of single-phase capacitor motors is proposed for variable speed control with good performance. The related control mode and the calculation of some parameters are approached. Results show that this method has excellent characteristics of start and speed control, and is especially good at speed control of motors with constant torque and constant power. Besides, because the power circuit can also be used in three-phase motors’VVVF control, thismethod has a high practical value.