JPS56150987A - Controller for speed of wound-rotor induction motor - Google Patents

Abstract

PURPOSE:To hold a power-factor in an ideal value by controlling the amount of power at the secondary side of a motor returned to a power source by difference between reactive power at the primary side and reactive power set and signals obtained by adding secondary current signals to difference signals between actual speed and set speed. CONSTITUTION:Reference reactive power is given by a resistor 25, and controls a converter 3 at the secondary side of a motor 1 through a computing element 28 and a phase control circuit 30 together with reactive power signals from a reactive power detecting circuit 10 at the primary side. Reference speed is given by a resistor 15, inputted to a computing element 18 together with actual speed and changed into reference torque, actual torque signals from a torque detecting circuit 14 are further added and an inverter 4 is controlled through a phase control circuit 24. Thus, since a minor loop of speed control is controlled by torque, the variation of a main circuit due to the control of a power-factor has no effect on speed control, reactive power at the power source side is freely controlled and an ideal power-factor can be obtained.