Motor drive control apparatus having a plurality of motor characteristics

Abstract

A motor drive control apparatus for controlling an induction motor based on a primary current including a magnetic flux current and a torque current includes a circuit for determining air gap magnetic flux according to a first magnetic flux characteristic curve and a torque current limiting value according to a first torque current characteristic curve in a first speed range; and for determining the air gap magnetic flux according to a second magnetic flux characteristic curve and the torque current limiting value according to a second torque current characteristic curve in a second speed range. A motor driving circuit causes the magnetic flux current corresponding to the air gap magnetic flux and the torque current corresponding to the torque current limiting value to flow in the motor. The first magnetic flux characteristic curve, the first torque current characteristic curve, the second magnetic flux characteristic curve and the second torque current characteristic curve are defined with respect to the operating speed of the motor. The first speed range is defined by a minimum speed and a switching speed of the motor while the second speed range is defined by the switching speed and a higher speed of the motor, often the maximum speed. The circuit can include a memory for storing data corresponding to each of the first magnetic flux characteristic curve, the first torque current characteristic curve, the second magnetic flux characteristic curve and the second torque current characteristic curve.