Terminal-impedance control for energy-saving in induction motors at no and partial loads using microprocessor

A theoretical actual nonlinear mathematical model for induction motor running at no and partial loads and fed from a thyristorized AC voltage controller, was introduced to determine optimum slips required for energy-saving achievement when running at maximum efficiency and power factor (PF), minimum active and reactive power, minimum stator current and losses. A software package in BASIC was introduced to determine the net energy saving when using the controller, the critical value for the load torque at which the net energy equals zero, and the control parameters required for optimum-slip detection. Finally, the open-loop control technique was implemented to check the computed results required for the terminal-impedance closed-loop control system. A comparison study between experimental and computed results was introduced. Finally, experimental open-loop control parameters were tabulated in the look-up table to drive the implemented closed-loop technique that include the current limiting loop required through starting