A low-cost adjustable speed drive for three phase induction motor

This paper describes the development a low-cost adjustable speed drive for three phase induction motor. The system consists of two modules, control, and power. The control module consists of an analog controller (relaxation oscillator) depending on the complexity of the application. For simple processes, resistance adjustment can change the motor speed as necessary. The power module is sized to capacity requirements and motor receiving the corresponding signal, being able to replace depending on the motor, and such Triacs or SCRs. Then, a linear response was obtained through the change of a resistor with low voltage and current THD. For this study, was used squirrel cage induction motor with 4-poles, 2-hp of nominal power and 208-V, 60-Hz.