SYNCHRONOUS MOTOR CONTROL DEVICE, COMPRESSOR DRIVE DEVICE, AIR-CONDITIONER, AND METHOD FOR CONTROLLING SYNCHRONOUS MOTOR

There is provided a synchronous motor control device including: a DC power supply 1; an inverter main circuit 2; a three-phase synchronous motor 3 that is driven when a direct current of the DC power supply 1 is converted into an alternating current by the inverter main circuit 2; and an inverter control unit 6 that receives an angular velocity command value, a phase current value of the three-phase synchronous motor 3 and a DC voltage value of the DC power supply 1 as input and outputs a PWM signal used to control the inverter main circuit 2, the inverter control unit 6 including: a PWM signal generation unit 10; a start-up control unit 8 that outputs a start-up voltage command value corresponding to the phase current value to the PWM signal generation unit 10 at the time of start-up; a steady state control unit 13 that calculates a steady state voltage command value by using a voltage equation in a steady state and outputs the value to the PWM signal generation unit 10; and a steady state control parameter initial value calculation unit 12 that outputs an initial value of a control parameter to be used in the steady state control unit 13 to the steady state control unit 13 such that an output voltage vector from the inverter main circuit 2 to the three-phase synchronous motor 3 is consistent before and after switching from the start-up to the steady state, whereby the start-up can be stably performed.