Patent ID: 9419550
Filing Date: 2016-08-16
CPC Classification: H02P

Claim Text:
1. A method of controlling torque of a permanent magnet synchronous motor (PMSM) by using a speed-torque lookup table, the method comprising: receiving a current direct-current (DC) link voltage of an inverter configured to drive the PMSM and a speed of a rotor of the PMSM; calculating a change ratio of a DC link voltage based on the current DC link voltage and a DC link voltage at a time when the speed-torque lookup table is generated; adjusting the change ratio of the DC link voltage based on a voltage limiting circle when the voltage limiting circle of an inverter output voltage becomes smaller than a command voltage of a current controller configured to control a current applied to the PMSM; calculating a normalized speed of the rotor by dividing the speed of the rotor by the adjusted change ratio of the DC link voltage; and transferring the normalized speed of the rotor as an input to the speed-torque lookup table.