| US 7,514,888 B2 | ||
| Method and system for sensorless brushless DC motor control with predictive switch timing | ||
| Anthonius Bakker, Morgan Hill, Calif. (US); and Navdeep Singh Dhanjal, San Jose, Calif. (US) | ||
| Assigned to Analog Devices, Inc., Norwood, Mass. (US) | ||
| Filed on Nov. 01, 2006, as Appl. No. 11/555,574. | ||
| Prior Publication US 2008/0101776 A1, May 01, 2008 | ||
| Int. Cl. H02P 6/18 (2006.01) | ||
| U.S. Cl. 318—400.34 [318/459; 318/500; 318/400.32] | 35 Claims |
| 1. A method of determining the position of a DC brushless motor's permanent magnet rotor which moves in response to the application
of an excitation voltage across the motor's stator coil, comprising:
applying an excitation voltage across at least one stator coil for a predetermined ON-time period;
deactivating said excitation voltage at the end of said predetermined ON-time period;
monitoring the voltage (VEMF) across said at least one stator coil generated by the electro-motive force (EMF) induced in said at least one stator coil
by said rotor when said excitation voltage is deactivated, said at least one stator coil connected in a full-bridge configuration;
and
detecting when VEMF changes polarity while said excitation voltage is deactivated, such that said change of polarity indicates when said motor
rotor has rotated a known distance with respect to its position at the time of its previous change of polarity.
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