Motor control device

1. A motor control device that detects a rotor position of a permanent magnetic synchronous motor through sensorless control, the motor control device comprising:

an inverter configured to detect an electric current flowing through a coil of the motor;

a Pulse Width Modulation (PWM) signal generating unit that is configured to detect, via the inverter, a voltage applied to the coil of the motor;

a rotor position detecting unit configured to detect:

a current phase, a current peak value and an induced voltage phase on the basis of the electric current detected by the inverter and the voltage detected by the PWM signal generating unit, and

the rotor position on the basis of the detected current phase, the detected current peak value, and the detected induced voltage phase;

a target current phase setting unit configured to:

set a target current phase on the basis of the current phase detected by the rotor position detecting unit, and

set a target current in a current vector control based on the rotor position detected by the rotor position detecting unit;

a revolution number detecting unit configured to:

set a number of revolutions of the motor on the basis of the rotor position detected by the rotor position detecting unit, and

detect a revolution number difference between the detected number of revolutions and a target number of revolutions instructed for the motor;

a voltage peak value detecting unit that is configured to detect an applied voltage peak value of a voltage applied to the coil, on the basis of the revolution number difference detected by the revolution number detecting unit; and

a phase voltage setting unit that is configured to set a target voltage on the basis of the target current phase set by the target current phase setting unit and the applied voltage peak value detected by the voltage peak value detecting unit, wherein

the phase voltage setting unit:

defines an actual current phase region including a current phase error range based on parameters to which is added an individual difference of at least any one of the motor and the inverter,

defines a stable operation current phase region in which the rotor position can be detected through the sensorless control, and

sets, as the target current, an electric current obtained by adding a predetermined phase difference corresponding to the number of revolutions detected by the revolution number detecting unit to an electric current set by the current vector control such that the actual current phase region is within the stable operation current phase region.

2. The motor control device according to claim 1 , wherein the phase voltage setting unit includes a data table for enabling the target current to be selected using the number of revolutions detected by the revolution number detecting unit as a parameter.

3. The motor control device according to claim 2 , wherein the data table used in the phase voltage setting unit includes a first table applied when the number of revolutions detected by the revolution number detecting unit is equal to or smaller than a predetermined low revolution number range and a second table applied when the number of revolutions detected by the revolution number detecting unit is equal to or larger than a predetermined steady revolution number range.

4. The motor control device according to claim 3 , wherein the phase voltage setting unit calculates and sets a target current phase according to interpolation processing based on respective data of the first and second tables when the number of revolutions detected by the revolution number detecting unit is larger than the predetermined low revolution number range and smaller than the predetermined steady revolution number range.

5. The motor control device according to claim 1 , wherein the parameters to which the individual difference of at least any one of the motor and the inverter is added include at least any one of the electric current detected by the inverter, the voltage detected by the PWM signal generating unit, a permanent magnet magnetic flux of the motor, inductance, and winding resistance of the coil.

6. The motor control device according to claim 1 , wherein the current vector control is maximum torque/current control, which includes setting, as the target current, an electric current with which generated torque of the motor is maximized with respect to the electric current detected by the inverter.