Patent ID: 6040673
Filing Date: 2000-03-21
Classification: H02P

Abstract:
A motor control apparatus comprising:a motor;a main circuit dc source;a main circuit power element group for supplying power from the main circuit dc source to a drive coil of the motor;a line current detector for detecting a line current flowing to a drive coil of the motor, and outputting the detected line current as a line current measurement;a position detector for detecting movement of a moving element of the motor; anda current controller for controlling the line current so that movement detected by the position detector equals a desired value by applying a switching command signal to the main circuit power element group, the switching command signal being dependent upon a position deviation, which is a difference between movement detected by the position detector and the desired movement;wherein said current controller comprises:a line current command generator for outputting based on the position deviation a command signal indicative of a line current to flow to the motor;an average current controller for comparing a PWM carrier signal and a voltage command signal obtained by amplifying a difference between the line current measurement and line current command signal, and outputting a first switching command signal;an instantaneous current controller for outputting a second switching command signal based on a comparison of the line current measurement and line current command signal; anda switching command signal selector for selecting and outputting to the main circuit power element group as the switching command signal either the first switching command signal or second switching command signal; andthe switching command signal selector selects as the switching command signal the first switching command signal when the position deviation is within a specified range, and selects the second switching command signal when the position deviation is outside this specified range.