Title:
IMPROVEMENTS OF ACCURACY OF ROTOR POSITION DETECTION RELATING TO THE CONTROL OF BRUSHLESS DC MOTORS
Document Type and Number:
WIPO Patent Application WO/2010/023538
Kind Code:
A3
Abstract:
During operation of a 3 phase BLDC motor it is driven by use of a PWM waveform applied to one of the driven phase (curve a). The other driven phase is connected thereto but no driving signal is applied (curve b). The third phase is left floating (curve c). This allows the back EMF in the third phase to be monitored for the purpose of determining rotor position by detection of zero crossing points. The rapid switching of the PWM pulses causes ringing in the back EMF signal indicated for one pulse by the ringed portions 1 of curve c. The ringing in the back EMF signal introduces inaccuracy into position calculations derived from back EMF signal measurement. In order to reduce this ringing, in the present invention, a reverse pulse is applied to the other driving coil shown (curve b) prior to a PWM on pulse. The reverse pulse has a polarity such that it drives the phase current through the linked coils in a direction opposite to that caused by the PWM on pulse. This reverse pulse reduces the magnitude of the ringing in the back EMF signal.
Inventors:
PAINTZ CHRISTIAN (DE)
FREITAG THOMAS (DE)
FREITAG THOMAS (DE)
Application Number:
PCT/IB2009/006650
Publication Date:
April 22, 2010
Filing Date:
August 26, 2009
Export Citation:
Assignee:
MELEXIS NV (BE)
PAINTZ CHRISTIAN (DE)
FREITAG THOMAS (DE)
PAINTZ CHRISTIAN (DE)
FREITAG THOMAS (DE)
International Classes:
H02P6/14; H02P6/16; H02P6/18
Foreign References:
| US6111372A | 2000-08-29 | |||
| EP1701437A2 | 2006-09-13 | |||
| JPS6450787A | 1989-02-27 |
Attorney, Agent or Firm:
SLATTERY, David et al. (Charles House148/9 Great Charles Street, Birmingham B3 3HT, GB)
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