Patent ID: 8065050

Claim:
A method for detecting an insufficient phase current in a motor powered by a three-phase alternating current (AC), the method comprising: determining a plurality of motor control parameters, including a commanded flux current and a commanded torque current; measuring an individual phase current for each phase of the three-phase AC within the motor only when each of the plurality of motor control parameters exceeds a corresponding threshold to thereby determine that a sufficiently large torque command has been issued to the motor; calculating a combined phase current using each of the measured individual phase currents; determining a composite vector position for the combined phase current with respect to a stationary frame of reference of the motor; assigning a sector number to the composite vector position, wherein the sector number defines a position of the composite vector within +/−30 degrees along three respective current axes for each of the three phases of the three-phase AC; comparing an absolute value of each of the individual phase currents to a corresponding calibrated threshold current corresponding to the sector number which is assigned; and executing at least one response when the absolute value of at least one of the individual phase currents is less than the corresponding calibrated threshold current.