Drive circuit for brushless DC motors
First Claim
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1. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:
- first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed;
commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and
a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed, wherein the moments of commutation are shifted as a function of the motor speed according to a linear function.
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Abstract
A drive circuit for brushless DC motors comprising a rotor and a stator with at least one stator coil includes a commutation device which supplies commutation pulses of drive current to the stator coil(s). The commutation device senses the rotor position and calculates current rotor speed therefrom. The rotor speed is then used to shift the commutation currents according to predetermined functions. The shifting of commutation currents is occasioned by shifting either or both of the ignition part of a commutation pulse and the extinction part of such pulses.
33 Citations
54 Claims
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1. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:
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first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed; commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed, wherein the moments of commutation are shifted as a function of the motor speed according to a linear function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 30)
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28. A drive circuit for a brushless DC motor with a rotor and a stator housing at least one stator coil, said drive circuit comprising:
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first apparatus for measuring angular position of the rotor relative to the stator and for determining motor speed; commutator means for connecting and interrupting current to the stator coil at specified moments of commutation determined from the angular rotor position relative to the stator; and a commutation shifting apparatus for shifting the specified moments of commutation, the amount of shifting being a predetermined function of motor speed, wherein the predetermined function is a nonlinear function. - View Dependent Claims (29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification