Apparatus for measuring magnetic flux of synchronous reluctance motor and sensorless control system for the same motor

A sensorless control system of a synchronous reluctance motor, the system comprising:

• a sensorless controller that measures a magnetic flux of a synchronous reluctance motor and that estimates a rotation angle and speed of the motor based on the measured flux in to control the motor;
• a low-speed-region tracker, which is activated or not activated based on the estimated speed of the motor, that measures the rotation angle and speed of a rotor of the motor so as to compensate the estimated rotation angle and the estimated speed of the sensorless controller;
• and
• a mode switching controller that controls whether to activate the low-speed-region tracker based on the estimated speed of the motor, and stabilizes chattering phenomena caused by the turning on or off of the low-speed-region tracker.

A method of measuring a magnetic flux of a synchronous reluctance motor comprising:

• estimating a flux of a synchronous reluctance motor by removing higher harmonic components of a current which flows into the motor in a rotational coordinate system;
• measuring a flux in a fixed coordinate system by combining a voltage in the fixed coordinate system, which is applied to the motor, and a current in the fixed coordinate system, from which higher harmonic components are removed, with the estimated flux of the motor;
• and
• converting the measured flux of the motor to a measured flux in the rotational coordinate system.