MOTOR CONTROL DEVICE FOR CONTROLLING CURRENT PHASE ON dq/THREE-PHASE COORDINATES

Patent metadata

Field	Value
Publication number	US-2016126871-A1
Application number	US-201514926344-A
Country	US
Kind code	A1
Filing date	Oct 29, 2015
Priority date	Oct 31, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

A motor control device for controlling a three-phase AC motor by using dq-three-phase coordinate conversion includes a phase correction amount calculation unit for calculating a phase correction amount by using a detected motor speed and a q-axis current command initial value, a rotor phase angle correction unit for adding or subtracting the phase correction amount to or from a detected rotor phase angle of the motor to calculate a corrected rotor phase angle, and a coordinate conversion unit for performing coordinate conversion between parameters on a dq coordinate system and parameters on a three-phase coordinate system on the basis of the corrected rotor phase angle.

First claim

What is claimed is:

1 . A motor control device for controlling a three-phase AC motor by using dq-three-phase coordinate conversion, the motor control device comprising:
a phase correction amount calculation unit for calculating a phase correction amount by using a detected motor speed and a q-axis current command initial value; a rotor phase angle correction unit for adding or subtracting the phase correction amount to or from a detected rotor phase angle of the motor to calculate a corrected rotor phase angle; and a coordinate conversion unit for performing coordinate conversion between parameters on a dq coordinate system and parameters on a three-phase coordinate system on a basis of the corrected rotor phase angle.

2 . The motor control device according to claim 1 , wherein the phase correction amount calculation unit comprises a storage unit for storing a speed coefficient N A , a first reference speed N B , a phase correction amount limit value N L , a current coefficient T A , and a reference current rate T B as predetermined parameters; a speed correction term calculation unit for calculating a speed correction term on a basis of:
Speed correction value=min[ N A ×max{0, ( N−N B )}, N L ]

where N represents the motor speed;
a current correction term calculation unit for calculating a current correction term on a basis of:
Current correction value= T A ×min[1,max{0, ( T A −T B )}]

where T r represents an initial q-axis current command rate that is a percentage of a q-axis current command initial value with respect to a maximum current outputtable by an inverter that converts DC power into AC power to supply the AC power as a drive power for the motor; and
an output unit for outputting, as the phase correction amount, a value obtained by multiplying the speed correction term and the current correction term together.

3 . The motor control device according to claim 2 , wherein the storage unit further stores a reference voltage as a predetermined parameter, and the phase correction amount calculation unit comprises a correction unit for correcting the speed coefficient, the first reference speed, and the phase correction amount limit value, respectively, read out from the storage unit, by using a DC voltage value detected on a DC side of the inverter and the reference voltage pre-stored in the storage unit.

4 . The motor control device according to claim 1 , further comprising a d-axis current command initial value calculation unit for calculating a d-axis current command initial value comprising a function that uses the motor speed as an independent variable.

5 . The motor control device according to claim 4 , wherein the d-axis current command initial value calculation unit calculates the d-axis current command initial value on a basis of:
Initial value of d -axis current command=max{0, I DA ×( N−I DB )}

where I DA represents a predetermined d-axis current command initial value coefficient and I DB represents a predetermined second reference speed.

6 . The motor control device according to claim 1 , wherein the rotor phase angle correction unit further adds or subtracts, to or from the corrected rotor phase angle, a phase angle corresponding to a time delay in a current control loop that controls so that a current that flows to the motor follows a current command, a phase angle corresponding to a phase advance of a q-axis current command necessary to maximize torque of the motor, or both of the phase angles to calculate a new corrected rotor phase angle that is used for the coordinate conversion by the coordinate conversion unit.

Assignees

• Fanuc Corp

Inventors

• Uematsu Hidetoshi

Classifications

• H02P21/0096

  Electricity · mapped topic

• H02P6/142 Primary

  Electricity · mapped topic

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02P6/15 Primary

  Controlling commutation time · CPC title

• H02P21/10

  Direct field-oriented control; Rotor flux feed-back control · CPC title