Permanent magnetic motor common leg impedance compensation means

Claim 2

A permanent magnet motor for a sensing device, characterized by: a permanent magnet rotor; a two-phase stator including a driving winding for providing a driving signal having a first phase and a sensing winding magnetically coupled to the driving winding for providing a sensing signal having a second phase; an undesired common impedance connected to the driving winding and to the sensing winding; power means for providing a power signal, and connected to the driving winding for applying said power signal thereto, with a portion of the driving signal appearing across the undesired common impedance and becoming a part of the sensing signal; means connected to the sensing winding and to the undesired common impedance for combining the sensing signal and the signal across the common impedance; means connected to the power means and to the combining means for feeding back the combined signal to the power means to compensate for that portion of the driving signal appearing across the undesired common impedance and which becomes a part of the sensing signal; and the power means being responsive to the combined signal fed back thereto for providing the power signal.

Claim 3

A permanent magnet motor for a sensing device as described by claim 1, further characterized by: the driving winding having first and second legs; the common impedance having first and second legs; the power means connected to one of the first and second legs of the driving winding, with the other of said legs of the driving winding connected to one of the first and second legs of the common impedance; and the other of said legs of the common impedance connected to ground.

Claim 4

A permanent magnet motor for a sensing device as described by claim 1, further characterized by: the sensing winding having first and second legs; one of the first and second legs of the sensing winding connected to the combining means, with the other of said legs of the sensing winding connected to the other leg of the common impedance.

Claim 5

A permanent magnet rotor for a sensing device as described by claim 1, wherein the means connected to the power means and to the combining means for feeding back the combined signal to the power means is characterized by: means connected to the power means for conditioning the power signal therefrom; the means connected to the sensing winding and to the undesired common impedance for combining the sensing signal and the signal across the common impedance including means responsive to the sensing signal and to the signal across the impedance for providing a buffered signal representing the back EMF of the sensing winding; means connected to the power signal conditioning means and to the buffered signal means for differentially summing the signals therefrom and for providing a differentially summed signal; means for phase shifting and integrating the differentially summed signal; means for detecting the zero crossing of the phase shifted and integrated signal; first means connected to the zero crossing detecting means for providing a rectangular pulse output of a first predetermined phase; second means for providing a reference rectangular pulse output of a second predetermined phase; means for locking the phase of the pulse output from the first neans to the phase of the pulse output from the second means, and for providing a phase locked pulse output; means for filtering the phase locked pulse output; means for commutating the filtered, phase locked pulse output; and the power means connected to the commutating means and responsive to the commutated, filtered, phase locked pulse output for providing the power signal.

Claim 6

A permanent magnet motor for a sensing device as described by claim 4 characterized by: the commutating means connected to the zero crossing detecting means for imparting frequency and time characteristics to the commutating means.