Method and system for improved closed loop control of sensorless brushless DC motors
First Claim
Patent Images
1. A method for electronically commutating a motor having a plurality of phase windings associated therewith, the method comprising:
- sensing a back electromotive force (BEMF) generated by each of the phase windings; and
scaling the magnitude of sensed BEMF values for each of the phase windings to a normalized value to produce gain corrected BEMF signals using an automatic gain control circuit;
wherein said gain corrected BEMF signals are used to determine a rotor position of the motor.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for electronically commutating a motor having a plurality of phase windings associated therewith is disclosed. In an exemplary embodiment, the method includes sensing a back electromotive force (BEMF) generated by each of the phase windings, and scaling the magnitude of the sensed BEMF values for each of the phase windings to a normalized value to produce gain corrected BEMF signals. The gain corrected BEMF signals are then used to determine a rotor position of the motor.
52 Citations
14 Claims
-
1. A method for electronically commutating a motor having a plurality of phase windings associated therewith, the method comprising:
-
sensing a back electromotive force (BEMF) generated by each of the phase windings; and
scaling the magnitude of sensed BEMF values for each of the phase windings to a normalized value to produce gain corrected BEMF signals using an automatic gain control circuit;
wherein said gain corrected BEMF signals are used to determine a rotor position of the motor. - View Dependent Claims (2, 3, 4)
determining when the magnitude of said gain corrected BEMF signals cross a neutral voltage of the motor; and
based upon the determination of said gain corrected BEMF signals crossing said neutral voltage of the motor, applying a control signal to an inverter, said inverter for selectively causing current to be applied to the plurality of phase windings.
-
-
4. The method of claim 1, wherein the sensed BEMF values are attenuated values of the BEMF generated by the phase windings.
-
5. A control circuit for a sensorless brushless motor, comprising:
-
a controller for receiving a sensed back electromotive force (BEMF) generated by each of a plurality of phase windings of the motor; and
an automatic gain control circuit for scaling the magnitude of sensed BEMF values for each of the phase windings to a normalized value to produce gain corrected BEMF signals;
wherein said gain corrected BEMF signals are used by said controller to determine a rotor position of the motor. - View Dependent Claims (6, 7, 8, 9)
means for determining when the magnitude of said gain corrected BEMF signals cross a neutral voltage of the motor; and
an inverter, operated by a control signal applied by said controller, said inverter for selectively causing current to be applied to the plurality of phase windings based upon a determination by said controller of said gain corrected BEMF signals crossing said neutral voltage of the motor.
-
-
9. The control circuit of claim 8, wherein said neutral voltage is computed from voltages of each of said plurality of phase windings.
-
10. A sensorless brushless motor, comprising:
-
a plurality of phase windings energized by a direct current source;
an inverter for sequentially applying phase current from said direct current source through selected pairs of phase windings;
a controller for receiving a sensed back electromotive force (BEMF) generated by each of said plurality of phase windings of the motor, said controller providing corresponding control signals to control switching of said inverter; and
an automatic gain control circuit for scaling the magnitude of sensed BEMF values for each of said plurality of phase windings to a normalized value to produce gain corrected BEMF signals;
wherein said gain corrected BEMF signals are used by said controller to determine a rotor position of the motor. - View Dependent Claims (11, 12, 13, 14)
said controller further comprises means for determining when the magnitude of said gain corrected BEMF signals cross a neutral voltage of the motor, and said inverter is operated by a control signal applied by said controller, said inverter for selectively causing current to be applied to said plurality of phase windings based upon a determination by said controller of said gain corrected BEMF signals crossing said neutral voltage of the motor.
-
-
14. The motor of claim 13, wherein said neutral voltage is computed from voltages of each of said plurality of phase windings.
Specification