Patent ID: 9136789
Filing Date: 2015-09-15
Classification: H02P

Abstract:
1. A synchronous motor control apparatus that performs current vector control of a permanent-magnet synchronous motor based on a q-phase current command and a d-phase current command, comprising: a first candidate value calculating unit which, using the motor speed of said synchronous motor and a control apparatus current limit value and control apparatus voltage limit value preset in said control apparatus, calculates a first d-phase current limit candidate value and a first q-phase current limit candidate value, based on points of intersection at which a current limiting circle representing a current vector locus that said control apparatus current limit value describes on a d-q current coordinate plane intersects a voltage limiting ellipse representing a current vector locus that said control apparatus voltage limit value describes as a function of said motor speed; a second candidate value calculating unit which, using the motor speed of said synchronous motor and said control apparatus voltage limit value, calculates a second d-phase current limit candidate value and a second q-phase current limit candidate value, based on points of intersection at which a maximum torque/flux curve representing a current vector locus that maximizes torque for the same flux linkage on said d-q current coordinate plane intersects said voltage limiting ellipse representing the current vector locus that said control apparatus voltage limit value describes as a function of said motor speed; a first q-phase current command unit which, when the absolute value of said first d-phase current limit candidate value is smaller than the absolute value of said second d-phase current limit candidate value, then sets said first q-phase current limit candidate value as a q-phase current limit value, but otherwise sets said second q-phase current limit candidate value as the q-phase current limit value and, when a first q-phase current command candidate value created based on a torque command exceeds said q-phase current limit value, then limits said first q-phase current command candidate value to said q-phase current limit value and outputs said limited first q-phase current command candidate value; a first d-phase current command unit which, when the absolute value of said first d-phase current limit candidate value is smaller than the absolute value of said second d-phase current limit candidate value, then sets said first d-phase current limit candidate value as a d-phase current limit value, but otherwise sets said second d-phase current limit candidate value as the d-phase current limit value and, when a first d-phase current command candidate value created based on said motor speed and said first q-phase current command candidate exceeds said d-phase current limit value, then limits said first d-phase current command candidate value to said d-phase current limit value and outputs said limited first d-phase current command candidate value; a third candidate value calculating unit which calculates a third d-phase current limit candidate value and a third q-phase current limit candidate value, based on points of intersection at which a maximum torque/current curve representing a current vector locus that maximizes generated torque for the same current on said d-q current coordinate plane intersects said current limiting circle representing the current vector locus that said control apparatus current limit value describes; a second q-phase current command unit which, when a second q-phase current command candidate value created based on said torque command exceeds said third q-phase current limit candidate value, then limits said second q-phase current command candidate value to said third q-phase current limit value and outputs said limited second q-phase current command candidate value; a second d-phase current command unit which outputs a second d-phase current command candidate value that is created by using said second q-phase current command candidate value output from said second q-phase current command unit and said maximum torque/current curve representing on said d-q current coordinate plane said current vector locus that maximizes generated torque for the same current; and a d-q phase current command judging unit which, when the absolute value of said second d-phase current command candidate value is larger than the absolute value of said first d-phase current command candidate value, then outputs said second d-phase current command candidate value and said second q-phase current command candidate value, otherwise outputs said first d-phase current command candidate value and said first q-phase current command candidate value, as said d-phase current command and said q-phase current command, respectively.