APPARATUS FOR CONTROLLING 3-PHASE MOTOR AND METHOD FOR MAINTAINING HIGH TORQUE THEREIN
Provided are an apparatus for controlling a 3-phase motor and a method for maintaining a high torque therein, which are capable of preventing excessive heat generation in a coil, through which a phase current flows, by causing an AC current to flow in a specific phase when a 3-phase motor maintains a high torque. The apparatus for controlling the 3-phase motor includes: a sensor configured to sense torques flowing through three phases of the 3-phase motor; and a controller configured to determine whether the torques of the three phases, which are detected by the sensor, maintain a high torque, and to perform control such that, when it is determined that the detected torques maintain the high torque, a DC signal is applied to a specific phase among the three phases and an AC signal is applied to the other phases.
1 . An apparatus for controlling a 3-phase motor, comprising:
a sensor configured to sense torques flowing through three phases of the 3-phase motor; and
a controller configured to determine whether the torques of the three phases, which are detected by the sensor, maintain a high torque, and to perform control such that, when it is determined that the detected torques maintain the high torque, a DC signal is applied to a specific phase among the three phases and an AC signal is applied to the other phases.
2 . The apparatus according to claim 1 , wherein the controller applies an AC voltage to a first phase requiring highest current among the three phases, applies an AC voltage to a third phase leading the first phase by 120°, and applies a DC voltage to a second phase lagging behind the first phase by 120°.
3 . The apparatus according to claim 2 , wherein the controller controls magnitudes of the voltages applied to the 3-phase motor such that a total sum of the voltages of the first phase, the second phase, and the third phase becomes zero.
4 . The apparatus according to claim 2 , wherein the AC voltages applied to the first phase and the third phase are a sine wave.
5 . A method for maintaining a high torque in an apparatus for controlling a 3-phase motor, the method comprising:
receiving torques flowing through the 3-phase motor;
determining whether the received torques of three phases maintain a high torque; and
performing control such that, when it is determined that the detected torques maintain the high torque, a DC signal is applied to a specific phase among the three phases and an AC signal is applied to the other phases.
6 . The method according to claim 5 , wherein in the controlling step, an AC voltage is applied to a first phase requiring highest current among the three phases, an AC voltage is applied to a third phase leading the first phase by 120°, and a DC voltage is applied to a second phase lagging behind the first phase by 120°.
7 . The method according to claim 6 , wherein in the controlling step, magnitudes of the voltages applied to the 3-phase motor are controlled such that a total sum of the voltages of the first phase, the second phase, and the third phase becomes zero.