Patent ID: 7567055
Filing Date: 2009-07-28
Classification: H02P

Abstract:
1. A controller for a brushless motor, comprising a current detection part that detects a current flowing in an armature winding of said motor; a rotation position detection part that detects a rotation position of a rotor of said motor; a dq-axes target current calculation part that calculates a d-axis target current and a q-axis target current, where an axis along a magnetic flux direction of a field system of said rotor is taken as the d axis, and an axis perpendicular to said d axis and a rotation axis of said rotor is taken as the q axis; a dq-axes current calculation part that determines a d-axis current and a q-axis current based on the detected current and the detected rotation position; a d-axis target voltage calculation part that determines a d-axis target voltage based on a feedback calculation for said d-axis current so as to decrease a d-axis difference between said d-axis target current and said d-axis current; and a q-axis target voltage calculation part that determines a q-axis target voltage based on a feedback calculation for said q-axis current so as to decrease a q-axis difference between said q-axis target current and said q-axis current, wherein a rotation force of said rotor is generated by applying a voltage to said armature winding based on said d-axis target voltage, said q-axis target voltage, and the detected rotation position; a d-axis correction value calculation part for determining a d-axis correction value and a q-axis correction value calculation part for determining a q-axis correction value are provided; said d-axis target voltage is determined based on a value obtained by correcting a result of the feedback calculation for said d-axis current with said d-axis correction value; and said q-axis target voltage is determined based on a value obtained by correcting a result of the feedback calculation for said q-axis current with said q-axis correction value; said controller further comprising a dq-axes limiting value calculation part that determines a d-axis limiting value and a q-axis limiting value so that a target voltage applied to said armature winding does not exceed a set maximum value; a d-axis addition part that adds said d-axis correction value to the result of the feedback calculation for said d-axis current; a q-axis addition part that adds said q-axis correction value to the result of the feedback calculation for said q-axis current; a first d-axis limiter that limits an absolute value of the sum of said d-axis correction value and the result of the feedback calculation for said d-axis current to said d-axis limiting value; a second d-axis limiter that limits an absolute value of the result of the feedback calculation for said d-axis current to said d-axis limiting value; a first q-axis limiter that limits an absolute value of the sum of said q-axis correction value and the result of the feedback calculation for said q-axis current to said q-axis limiting value; and a second q-axis limiter that limits an absolute value of the result of the feedback calculation for said q-axis current to said q-axis limiting value, wherein an output value of said first d-axis limiter is treated as said d-axis target voltage; an output value of said first q-axis limiter is treated as said q-axis target voltage; an output value of said second d-axis limiter is used as a preceding value in the feedback calculation for said d-axis current in a next calculation cycle; and an output value of said second q-axis limiter is used as a preceding value in the feedback calculation for said q-axis current in a next calculation cycle.