US 11,973,444 B2
Determining rotor position offset for electrical machines
Siddharth Ballal, Fishers, IN (US); Arslan Qaiser, Fishers, IN (US); and Brandon P. Davis, Noblesville, IN (US)
Assigned to BORGWARNER INC., Auburn Hills, MI (US)
Filed by BorgWarner Inc., Auburn Hills, MI (US)
Filed on Jul. 27, 2022, as Appl. No. 17/874,610.
Prior Publication US 2024/0039442 A1, Feb. 1, 2024
Int. Cl. G01D 18/00 (2006.01); G01B 7/00 (2006.01); H02P 6/16 (2016.01); H02P 21/18 (2016.01); H02P 21/22 (2016.01)
CPC H02P 21/18 (2016.02) [G01B 7/003 (2013.01); H02P 6/16 (2013.01); H02P 21/22 (2016.02)] 15 Claims
OG exemplary drawing
 
1. A method of calibrating an electrical machine to determine an angular offset between a motor sensor indicated position and an actual rotor position, comprising the steps of:
(a) supplying electrical current to stator windings;
(b) identifying a quadrant of a rotor where a rotor pole is located;
(c) approximating a line between a torque value measured at a lower angular boundary of the identified quadrant and a torque value measured at an upper angular boundary of the identified quadrant; and
(d) determining an angular offset by locating an angular position where torque exerted by the rotor is zero.
 
7. A method of calibrating an electrical machine to determine an angular offset between a motor sensor indicated position and an actual rotor position, comprising the steps of:
(a) supplying electrical current to stator windings;
(b) identifying a quadrant of a rotor where a rotor pole is located;
(c) determining an initial angular offset position by approximating a line between a torque value measured at a lower angular boundary of the identified quadrant and a torque value measured at an upper angular boundary of the identified quadrant; and
(d) performing a bi-section search to determine a final angular offset by locating an angular position along the approximated line where torque exerted by the rotor is zero to improve the initial angular offset position;
(e) storing the angular offset in a control system.
 
12. A system configured to calibrate an electrical machine to determine an angular offset between a motor sensor indicated position and an actual rotor position, comprising:
a controller, wherein the controller includes non-volatile memory and programmed to supply electrical current to stator windings; identify a quadrant of a rotor where a rotor pole is located; approximate a line between a torque value measured at a lower angular boundary of the identified quadrant and a torque value measured at an upper angular boundary of the identified quadrant to determine an initial offset position value; and determine a final angular offset position by locating an angular position along the approximated line where torque exerted by the rotor is zero.