Harmonic cancellation in a variable coupling transformer

Claim 2

A position-measuring transformer, comprising: a first winding which defines substantially within a primary plane a pair of concentric spiral conductors of equal and constant pitch with a fixed angular displacement therebetween; a second winding rotatable with respect to said first winding about the axis of the spiral conductors, said second winding being substantially within a secondary plane parallel to said primary plane and having a pair of arcuate conductors concentric with said first winding, said arcuate conductors having a radial displacement therebetween substantially equal to an integral multiple of one-half of said pitch; and a third winding which is substantially within said primary plane concentric with said first winding and is defined by spiral conductors having said equal and constant pitch and said fixed angular displacement between each other, corresponding conductors of said first and third windings having a known angular displacement therebetween for the cancellation of a spatial harmonic of a spatial fundamental of a signal provided through said second winding in response to a carrier signal being provided to said first and third windings concurrently with said relative rotation where said known angular displacement is in accordance with a relationship which is given as:

Claim 3

Apparatus according to claim 1 wherein said known angular displacement is equal to the angular displacement of one-half cycle of a spatial harmonic component.

Claim 4

Apparatus according to claim 1 wherein said known angular displAcement is equal to 60*.

Claim 5

A position-measuring transformer comprising: a first primary winding including a plurality of first conductor portions which are arranged substantially within a primary plane parallel to each other with a known and equal displacement between adjacent first conductor portions, said first conductor portions being connected to provide equal currents flowing in opposite directions through said adjacent first conductor portions when said first winding is coupled to a voltage source; a secondary winding mounted for motion relative to said first winding, a component of said motion being in a direction normal to the direction of the extent of said first conductor portions, said secondary winding being substantially within a secondary plane parallel to said primary plane and having a pair of conductors substantially parallel to said first conductor portions, said conductors having a displacement therebetween substantially equal to the displacement between said adjacent first conductor portions; and a second primary winding including a plurality of second conductor portions which are arranged substantially within said primary plane parallel to said first conductor portions, said second conductor portions being connected to provide equal currents respectively flowing in opposite directions through adjacent second conductor portions when said second primary winding is connected to a voltage source, said first and second primary windings being respectively disposed to cause a cancellation of a spatial harmonic of a spatial fundamental of a signal which is provided by said secondary winding in response to a carrier signal being provided to said first and second primary windings concurrently with said relative motion; wherein each second conductor portion is displaced from a first conductor portion in accordance with a relationship which is given as:

Claim 6

A position-measuring transformer comprising: a first primary winding including a plurality of first conductor portions which are arranged substantially within a primary plane parallel to each other with a known and equal displacement between adjacent first conductor portions, said first conductor portions being connected to provide equal currents flowing in opposite directions through said adjacent first conductor portions when said first winding is coupled to a voltage source; a secondary winding mounted for motion relative to said first winding, a component of said motion being in a direction normal to the direction of the extent of said first conductor portions, said secondary winding being substantially within a secondary plane parallel to said primary plane and having a pair of conductors substantially parallel to said first conductor portions, said conductors having a displacement therebetween substantially equal to the displacement between said adjacent first conductor portions; and a second primary winding including a plurality of second conductor portions which are arranged substantially within said primary plane parallel to said first conductor portions, said second conductor portions being connected to provide equal currents respectively flowing in opposite directions through adjacent second conductor portions when said second primary winding is connected to a voltage source, said first and second primary windings being respectively disposed to cause a cancellation of a spatial harmonic of a spatial fundamental of a signal which is provided by said secondary winding in response to a carrier signal being provided to said first and second primary windings concurrently with said relative motion; wherein each second conductor portion is displaced from a first conductor portion in accordance with a relationship which is given as:

Claim 7

Apparatus according to claim 4 wherein the displacement between said first and second conductor portions is one-third of the displacement between adjacent first conductor portions.

Claim 8

Apparatus according to claim 4 wherein the displacement between said first and second conductor portions is equal to one-half cycle of a spatial harmonic component.

Claim 9

A transformer comprising relatively movable members, each having a winding, said windings being inductively related, the improvement wherein one of said windings has two sections, each section having conductor portions carrying current in opposite directions, the displacement between the conductor portions of said sections being the same, the conductor portions of each section being in series with each other and extending side by side in spaced parallel relationship to the conductor portions of the other section, and said sections each being electrically connected to an external circuit, the conductor portions of one of said sections being displayed between the conductor portions of the other section an amount equal to one-half cycle of an undesired spatial harmonic of a fundamental component of a voltage induced in one of said windings, during relative movement of said members, for substantially cancelling said spatial harmonic.

Claim 10

A transformer comprising relatively movable members, each having a winding, said windings being inductively related, the improvement wherein one of said windings has two sections, each section having conductor portions carrying current in opposite directions, the displacement between the conductor portions of said sections being the same, the conductor portions of each section being in series with each other and extending side by side in spaced parallel relationship to the conductor portions of the other section, and said sections each being electrically connected to an external circuit, the conductor portions of one of said sections being displayed between the conductor portions of the other section an amount equal to one-half cycle of an undesired spatial harmonic of a fundamental component of a voltage induced in one of said windings, during relative movement of said members, for substantially cancelling said spatial harmonic.

Claim 11

A transformer according to claim 7 wherein said members are relatively rotatable, each of said sections of said one winding being in the form of a spiral.

Claim 12

A transformer according to claim 7 wherein said members are relatively rotatable on an axis, each of said sections of said one winding being in the form of a spiral, said other winding comprising two pairs of winding groups, said pairs being arraNged in space quadrature, the winding groups of each pair being oppositely disposed on a diameter having a center at said axis, each group comprising a plurality of active conductors connected in series and located at different radial distances of said axis, the active conductor of each group being concentrically arcuate about said axis and having a pitch one-half the pitch of the spiral conductors of said winding.

Claim 13

A position measuring transformer according to claim 4 wherein said conductor portions of said first and second primary windings are substantially straight.