Disk drive motor position detection using mutual inductance zero crossing
AssigneeTexas Instruments Incorporated
InventorsTan Du, Robert E. Whyte, Jr.
Life of this patent
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Abstract
The invention includes a method and apparatus for detecting the position of an electric motor rotor by sensing the zero crossing or polarity change of a mutual inductance associated with the motor. The use of mutual inductance provides for consistent position detection unaffected by motor speed or winding current, thus providing significant advantages over traditional back emf zero crossing detection methods. The mutual inductance zero crossing may be detected by measuring a voltage signal in a floating phase of the motor, filtering back emf and excitation components out of the measured voltage signal, and detecting a polarity change or zero crossing in the resulting mutual inductance signal.
Claims21
A method of detecting rotor position in a polyphase electric motor, comprising:
- measuring a mutual inductance in the motor by using zero crossing of said polyphase electric motor;
- and
- determining the rotor position according to the measured mutual inductance,
- wherein determining the rotor position according to the measured mutual inductance comprises:
- detecting a polarity change in the measured mutual inductance;
- and
- determining the rotor position according to the mutual inductance polarity change.
An apparatus for detecting rotor position in a polyphase electric motor, comprising:
- a first circuit adapted to measure a mutual inductance in the motor by using zero crossing of said polyphase electric motor;
- and
- a second circuit adapted to determine rotor position according to the measured mutual inductance,
- wherein the second circuit is further adapted to detect a polarity change in the measured mutual inductance and to determine the rotor position according to the mutual inductance polarity change.
Dependencies are inferred from the claim text.