Rotor orientation detection in brushless DC motors

US7944159B2 · kind B2 · utility

Assignee

• MELEXIS NV · BE

Inventors

• Christian Paintz · Erfurt, DE
• Thomas Freitag · Hamburg, DE
• Detlef Klose · Ieper, BE

Key dates

• Filing date: Apr 18, 2008
• Grant date: May 17, 2011
• Expiry date: Jul 2, 2029

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02P6/15
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

In order to determine the orientation of the rotor of a brushless DC motor 100, a sequence of current pulses may be applied to the stator phases U, V, W by the respective drivers HS0, LS0, HS1, LS1, HS2, LS2. The current generated in the stator phases U, V, W in turn generates a current in a shunt resistor 110. The current in this shunt resistor 110 is monitored by use of a current voltage converter 120 and a comparator 130 to determine when it exceeds a predetermined threshold. The rise time until the threshold current is exceeded is recorded in capture unit 140. A processor unit 150 then calculates a scalar parameter SU, SV, SW for each respective stator phase U, V, W from the recorded rise times associated with each pulse. The orientation of the magnetic axis of the rotor can then be determined by consideration of the scalar parameters SU, SV, SW of each stator phase U, V, W, as the respective rise times of each pulse are determined by the inductive properties of the respective stator phases U, V, W, which in turn are dependent upon the orientation of the rotor.