Apparatus for operating interior permanent magnet synchronous motor

1. An apparatus for operating interior permanent magnet synchronous motor by receiving a command torque to drive an IPMSM in a system including a detector measuring a position and a speed of a rotor of the IPMSM, the apparatus comprising:

an output unit generating and outputting a current command driving a MTPA (Maximum Torque Per Ampere) based on the command torque; a correction unit correcting the current command outputted by the output unit; a feedback unit transmitting over-modulated voltage information to the correction unit; a control unit controlling the current command to output a voltage; a first limit unit limiting an output of the control unit using a maximum voltage synthesizable by an inverter unit; and the inverter unit applying a 3-phase voltage command for tracking a command torque to the IPMSM using an output of the first limit unit;

wherein the output unit comprises a second limit unit limiting a size of the torque command to a predetermined maximum range and a predetermined minimum range; a first calculation unit calculating a normalized command torque by dividing an output of the second limit unit by a normalized torque; a 1-D look-up table unit outputting a normalized current command by using the normalized command torque; and a second calculation unit outputting a current command driving a MTPA (Maximum Torque Per Ampere) by multiplying the normalized current command by the normalized current;

wherein the correction unit comprises a processing unit correcting a current command driving the MTPA (Maximum Torque Per Ampere) by using a unit vector maintaining a constant torque, and a third limit unit limiting the size of the current from the current command corrected by the processing unit;

wherein the third limit unit provides a priority to a d-axis current on the synchronous reference frame relative to the corrected current command, outputs the d-axis current on the priority within a size of a rated current, and selects as permissible range of a q-axis current command a balance where the size of the d-axis current is subtracted from the rated current.

2. The apparatus of claim 1 , further comprising a first conversion unit converting an output of the control unit on synchronous reference frame to a voltage on stationary reference frame using position information of the rotor received from the detector and outputting the converted output to the first limit unit.

3. The apparatus of claim 1 , further comprising current sensors measuring a phase current outputted from the inverter unit to the IPMSM.

4. The apparatus of claim 3 , further comprising a second conversion unit converting a phase current on stationary reference frame received from the current sensors to a current on the synchronous reference frame and providing the converted current to the correction unit and the control unit.

5. The apparatus of claim 1 , wherein the 1-D look-up table unit pre-determines and stores the normalized current command relative to the normalized command torque.

6. The apparatus of claim 1 , wherein the 1-D look-up table unit outputs normalized d and q axes current commands on the synchronous reference frame.

7. The apparatus of claim 1 , wherein the feedback unit feedbacks the output of the control unit and the over-modulated voltage synthesized by the inverter unit to the correction unit.

8. The apparatus of claim 7 , wherein the feedback unit integrates and high-pass filters the size of the over-modulated voltage, and transmits the integrated and high-pass filtered voltage to the correction unit.

9. The apparatus of claim 1 , wherein the first limit unit limits an output of the control unit by using a voltage limit hexagon.

10. The apparatus of claim 1 , wherein the third limit unit limits the corrected current command to a current range outputtable by the inverter unit.