Patent ID: 7852040

Claim:
A motor driver system comprising: an inverter that applies a motor driving 3-phase voltage to a motor; and an inverter driver that generates and outputs a command voltage to the inverter to make the speed of the motor follow a command velocity, wherein when the motor operates in a field weakening region, the inverter driver controls a magnetic flux command value to prevent a command current angle of a d-axis or q-axis command current from exceeding a pre-set value, wherein the inverter driver comprises: a d-axis voltage controller that generates a d-axis command voltage by varying a magnetic flux command value according to a d-axis current value and outputs the generated d-axis command value to the inverter, when a d-axis current value of the motor is lower than a pre-set lower limit value, and wherein the d-axis voltage controller comprises: a d-axis current calculating unit that periodically calculates the d-axis current value of the motor; a d-axis current comparing unit that compares the calculated d-axis current value and the pre-set lower limit value; a PI unit that integrates a difference value between the calculated d-axis current value and the pre-set lower limit value when the calculated d-axis current value is lower than the pre-set lower limit value; and a d-axis voltage generator that generates a d-axis command voltage by adding the integrated value output from the PI unit to an integrated value of a difference value between the magnetic flux command value and an integrated magnetic flux of the motor.