CONTROL GEAR AND METHOD FOR CONTROLLING INDUCTION MOTOR Russian patent published in 2002 - IPC

FIELD: electrical engineering; traction motors of vector-control electric drives for electric trains. SUBSTANCE: induction motor control gear has dc-to-ac voltage inverter with adjustable frequency and adjustable voltage in pulse-width modulation mode and inverter output voltage control circuit that functions to vary modulation percentage in response to commands on inverter output voltage variation effected on commands for changing magnetizing and torque-generating components of motor stator current, inverter voltage being applied to this motor. Control gear also has circuit for measuring torque-generating component of motor stator current; circuit correcting command to change magnetizing component of stator current according to difference between measured part of stator current magnetizing component and that of command; circuit correcting output frequency of inverter according to corrected command for changing magnetizing component of stator current used for base clipping of desired modulation percentage or according to other conditions. Control gear ensures reliable continuous vector control of induction motor in the range of low to high speeds at which value of command for voltage variation exceeds maximal output voltage of inverter as function of dc voltage. EFFECT: simplified design, provision for continuous control throughout entire speed range. 5 cl, 1 dwg