Motor control device

Abstract

Embodiments provide a motor control device configured to perform on/off control on a plurality of switching elements connected to each other in a three-phase bridge according to a PWM signal and to drive a motor via an inverter circuit that converts a direct current (DC) into a three-phase alternating current (AC), the motor control device including: a current detection element connected to a DC side of the inverter circuit to generate a signal corresponding to a current value; a PWM signal generation unit configured to determine a rotor position based on at least a phase current of the motor and to generate a PWM signal to follow the rotor position; and a current detection unit configured to detect the phase current of the motor based on the signal generated by the current detection element and the PWM signal; the PWM signal generation unit being capable of executing a first output method of outputting a phase-shifted PWM signal with three phases and causing the current detection unit to detect a current at fixed timing, a second output method of outputting a phase-shifted PWM signal with two phases and causing the current detection unit to detect a current at fixed timing, and a third output method of outputting a symmetrical PWM signal with three phases or two phases and causing the current detection unit to detect a current at fixed or variable timing, such that the current detection unit is capable of detecting two-phase currents at two timing points within a carrier wave cycle of the PWM signal, the motor control device further including: a magnetic flux estimation unit configured to estimate a magnetic flux interlinkage of an armature coil of the motor based on the phase current of the motor and an output voltage command; a signal switching output unit configured to estimate a rotating magnetic field angle and a speed of the motor based on the magnetic flux interlinkage, and to output a switching command such that the PWM signal generation unit executes the first output method when a modulation rate of a motor applied voltage is less than a first threshold value, executes the second output method when the modulation rate is the first threshold value or greater or less than a second threshold value, and executes the third output method when the modulation rate is the second threshold value or greater; and an angle compensation unit configured to use a speed estimated in a previous control cycle and to generate an angle computed based on the speed estimated in the previous control cycle when the motor current is not detectable in one cycle of an electrical angle.

Dependencies are inferred from the claim text.