DRIVING CONTROLLER FOR ALTERNATING-CURRENT MOTOR

摘要

PROBLEM TO BE SOLVED: To exercise control without detecting or calculating the angle of a rotor in a driving controller which exercises rectangular wave voltage control on an alternating-current motor. SOLUTION: A rectangular wave generating portion 56 switches SW patterns for realizing rectangular wave voltages corresponding to different phase values in the order of the phase values. A PI computing portion 58 exercises feedback control based on a command value and an estimated value of torque and calculates a command value Δθ* of rotor movement with the current SW pattern. The SW pattern is switched to the next SW pattern when the rotor is rotated by Δθ*. This timing is calculated using the angular speed of the rotor. A number of revolutions calculating portion 60 estimates the angular speed with the current SW pattern from the time before the previous SW pattern is switched to the current SW pattern and the command value Δθ* with the previous pattern. The power to the motor 52 used in torque estimation is estimated using the instantaneous value of rectangular wave voltage supplied from an inverter 54 to the motor 52.