Method for controlling permanent magnet synchronous motor

A method for controlling a permanent magnet synchronous motor, the method comprising:

• detecting an absolute angular position of a permanent magnet synchronous motor;
• calculating a rotational speed of the permanent magnet synchronous motor based on the detected absolute angular position;
• detecting a voltage of a battery as a power source;
• calculating a compensated speed, for which a battery voltage variation is compensated, from the rotational speed of the permanent magnet synchronous motor based on a torque command, the rotational speed of the permanent magnet synchronous motor, and the battery voltage;
• generating a d-axis current command and a q-axis current command corresponding to the torque command and the compensated speed using a predetermined current command map;
• converting three-phase currents flowing into the permanent magnet synchronous motor into a d-axis feedback current and a q-axis feedback current based on the detected absolute angular position;
• calculating a d-axis voltage command and a q-axis voltage command based on the d-axis current command, the q-axis current command, the d-axis feedback current, and the q-axis feedback current;
• converting the d-axis voltage command and the q-axis voltage command into three-phase voltage commands based on the detected absolute angular position;
• and
• controlling the operation of the permanent magnet synchronous motor based on the three-phase voltage commands,
• wherein the calculating the compensated speed comprises:
• determining whether the rotational speed of the permanent magnet synchronous motor is greater than a predetermined weight application speed;
• calculating an operating weight factor by applying a weight to the rotational speed and the torque command, if the rotational speed of the permanent magnet synchronous motor is greater than the weight application speed;
• and
• calculating the compensated speed, for which a battery voltage variation is compensated, from the rotational speed of the permanent magnet synchronous motor based on the operating weight factor and a reference voltage used when the current command map is set.