Fast rotor position detection apparatus and method for disk drive motor at standstill
AssigneeTexas Instruments Incorporated
InventorTan Du
Life of this patent
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Abstract
The invention includes a method and apparatus for detecting the position of a stationary rotor in a polyphase electric motor. The method includes providing one or more short duration voltage pulses to the motor and determining the rotor position based on measurements of one or more phase voltages. The invention allows identification of a region in which the rotor is positioned, through polarity sensing, whereby the rotor position may be quickly and accurately determined, to allow a stationary electric motor to be properly energized to rotate in a desired direction.
Claims27
A method of detecting a stationary rotor position in a polyphase electric motor, comprising:
- measuring a mutual inductance of the motor by using zero crossing of said polyphase electric motor;
- and
- determining the stationary rotor position according to the measured mutual inductance.
A method of detecting a stationary rotor position in a polyphase electric motor having first, second, and third phases, the method comprising:
- applying a first voltage pulse across the second and third phases while measuring a first floating phase voltage across the first phase during zero crossing of the first phase;
- applying a second voltage pulse across the third and first phases while measuring a second floating phase voltage across the second phase during zero crossing of the second phase;
- applying a third voltage pulse across the first and second phases while measuring a third floating phase voltage across the third phase during zero crossing of the third phase;
- and
- determining the stationary rotor position according to the measured first, second, and third floating phase voltages.
An apparatus for detecting a stationary rotor position in a polyphase electric motor having first, second, and third phases, comprising:
- a first circuit adapted to apply a first voltage pulse across the second and third phases and to measure a first floating phase voltage across the first phase by the zero crossing of the first phase;
- wherein the first circuit is further adapted to apply a second voltage pulse across the third and first phases and to measure a second floating phase voltage across the second phase by the zero crossing of the second phase;
- wherein the first circuit is further adapted to apply a third voltage pulse across the first and second phases and to measure a third floating phase voltage across the third phase by measuring the zero crossing of the third phase;
- and
- a second circuit adapted to determine the stationary rotor position according to the measured first, second, and third floating phase voltages.
Dependencies are inferred from the claim text.