Patent ID: 6812660
Filing Date: 2004-11-02
Classification: H02P

Abstract:
An apparatus for controlling a salient-pole DC brushless motor having armatures in three phases, comprising:voltage applying means for applying drive voltages to said armatures; high-frequency adding means for adding high-frequency voltages to said drive voltages; first current detecting means for detecting a current flowing through an armature in a first phase of said armatures in the three phases; second current detecting means for detecting a current flowing through an armature in a second phase of said armatures in the three phases; reference value extracting means for extracting a sine reference value depending on the sine value of a twofold angle which is twice a rotor angle of said motor and a cosine reference value depending on the cosine value of the twofold angle, using a first current value detected by said first current detecting means and a second current value detected by said second current detecting means when said high-frequency voltages are added to said drive voltages by said high-frequency adding means, and high-frequency components depending on said high-frequency voltages; rotor angle calculating means for calculating a rotor angle of said motor using said sine reference value and said cosine reference value; three-phase/dq converting means for handling said motor as an equivalent circuit having a q-axis armature disposed on a q-axis in the direction of magnetic fluxes from a rotor of the motor and a d-axis armature disposed on a d-axis which is perpendicular to the q-axis, and calculating a detected q-axis current flowing through said q-axis armature and a detected d-axis current flowing through said d-axis armature based on the rotor angle of said motor which is calculated by said rotor angle calculating means, said first current value, and said second current value; current control means for determining said drive voltages in order to eliminate a q-axis current difference which is the difference between the detected q-axis current and a predetermined q-axis command current and a d-axis current difference which is the difference between the detected d-axis current and a predetermined d-axis command current; and magnetic pole detecting means for carrying out a magnetic pole detecting process to detect the orientation of the magnetic poles of said rotor based on a magnetic pole reference value calculated by a predetermined calculating process, depending on said sine reference value and said cosine reference value which are extracted by said reference value extracting means when said q-axis command value current is set to a predetermined magnetic pole detecting current; said current control means comprising means for performing a proportional plus integral process on the difference between said detected q-axis current and said q-axis command current to calculate said q-axis current difference and also performing a proportional plus integral process on the difference between said detected d-axis current and said d-axis command current to calculate said d-axis current difference when said magnetic pole detecting process is not carried out, and performing an integral process only on the difference between said detected q-axis current and said q-axis command current to calculate said q-axis current difference and also performing an integral process only on the difference between said detected d-axis current and said d-axis command current to calculate said d-axis current difference when said magnetic pole detecting process is carried out.