DETECTING SYSTEM FOR INSTANTANEOUS TORQUE OF AC MOTOR

摘要

PURPOSE:To precisely detect the torque output by a system wherein currents and voltages for three phases are detected, primary and secondary voltage are calculated therefrom and then the secondary voltage is divided by the rotational speed of the motor. CONSTITUTION:In a current and voltage detecting circuit 100, currents are taken out through current transformers 4-6 and resistors 8-10 in the form of a voltage signal, and voltage signals are obtained through a three phase transformer. The value obtained by multipliers 21-23 and a square function generator 20 is subtracted from primary input P1 comprising respective outputs from multipliers 24-26 in an addition/subtraction unit 30. Commutation surges are subtracted in subtraction units 17-19 after passing through high harmonics pass filters 14-16. In a divider 31, secondary input given as output from the addition/subtraction unit 30 is divided by the rotational speed of a motor 2 so as to obtain instantaneous torque.