Structures and methods for controlling losses in printed circuit boards
The disclosure relates to printed circuit board motors and specifically to printed circuit boards used in motors and generators. Windings formed from copper on printed circuit boards have been used for purposes of forming antennas, inductors, transformers, and stators that can be incorporated in permanent magnet brushless DC (permanent magnet synchronous) machines. For energy conversion devices using modern permanent magnet materials and PCB stators, the magnetic field is not strongly confined by magnetically susceptible materials. Thus, the interaction between fields from adjacent turns in a winding, and/or windings on adjacent layers (for a multilayer configuration) may be significant. The structures disclosed hereinafter reduce the effective resistance in the windings, and therefore reduce the associated losses to achieve a reduced current density in portions of the rotating energy conversion devices. The effect of the disclosed structures is a measurable reduction in loss mechanisms as a function increasing frequency, compared to the currently available devices. These effects are significant in frequency ranges important to energy conversion processes as well as typical control strategies, for example, pulse-width modulation.
1. An apparatus for use in a motor or generator, comprising:
a planar composite structure (PCS) comprising at least one dielectric layer and a conductive pattern on a surface of each said dielectric layer, said conductive pattern comprising;
a plurality of conductive traces, each extending radially from an inner radius to an outer radius and disposed angularly on one of the dielectric surfaces; and
an interconnect having a starting region, a transition region, and an ending region, the starting region being connected to the outer radius of at least a first conductive trace of the plurality of conductive traces, and the ending region being connected to the outer radius of at least a second conductive trace of the plurality of conductive traces, the interconnect being bounded by an inner edge and an outer edge, and having a first radiused inner edge section extending from the outer radius of the first conductive trace to the transition region, and a second radiused inner edge section extending from the transition region to the outer radius of the second conductive trace;
wherein at least the first radiused inner edge section and the second radiused inner edge section are each characterized at least in part by the Corner Equation
r (θ)= r d +( r s −r d ) e −(θ−θ s )/α
for a corner starting at θ s and r s and evaluated for θ>θ s , or the equivalent reflected version with
r (θ)= r d +( r s −r d ) e −(θ s −θ)/α
for a corner evaluated with θ<θ s and ending at θ s and r s , and
where the angular separation between the first and second conductive traces is δ radians, and α ranges between 0.068 and 0.2δ radians.
2. The apparatus of claim 1 wherein the Corner Equation for the entire inner edge region of the interconnect is characterized by the single equation
r
(
θ
)
=
r
s
1
+
(
r
d
-
r
s
1
)
(
1
-
e
-
θ
-
θ
1
α
)
+
(
r
s
2
-
r
d
)
(
e
-
θ
2
-
θ
α
)
where r s1 , θ 1 is the starting point of the structure at the initiating trace, r s2 , θ 2 is the ending point of the structure, and r d is the radius at which the structure extends primarily in the angular direction.
3. The apparatus of claim 1 , wherein:
the PCS comprises a multi-layer printed circuit board, and
the apparatus further comprises a connector that interconnects the second conductive trace to another of the plurality of conductive traces on a different layer of the printed circuit board.
4. The apparatus of claim 1 , wherein the PCS is configured for use as a stator in the motor or generator.
5. An apparatus for use in a motor or generator, comprising:
a planar composite structure (PCS) comprising at least one dielectric layer and a conductive pattern on a surface of each said dielectric layer, at least one conductive pattern comprising;
a plurality of conductive traces, each extending radially from an inner radius to an outer radius and disposed angularly on one of the dielectric surfaces; and
an interconnect having a starting region, a transition region, and an ending region, the starting region being connected to the outer radius of at least a first conductive trace of the plurality of conductive traces, and the ending region being connected to the outer radius of at least a second conductive trace of the plurality of conductive traces, the interconnect being bounded by an inner edge and an outer edge, and having a first radiused inner edge section extending from the outer radius of the first conductive trace to the transition region, and a second radiused inner edge section extending from the transition region to the outer radius of the second conductive trace;
wherein the interconnect is configured and arranged on the PCS such that, at any point between the inner and outer edge, the smallest current density magnitude under direct current excitation is not less than 50% of the largest current density magnitude evaluated along the shortest line between the inner and outer edge passing through that point.
6. The apparatus of claim 5 , wherein:
the PCS comprises a multi-layer printed circuit board, and
the apparatus further comprises a connector that interconnects the second conductive trace to another of the plurality of conductive traces on a different layer of the printed circuit board.
7. The apparatus of claim 5 , wherein the PCS is configured for use as a stator in the motor or generator.
8. A apparatus for use in a motor or generator, comprising:
a planar composite structure (PCS) comprising at least one dielectric layer and a conductive pattern on a surface of each said dielectric layer, at least one conductive pattern comprising;
a plurality of conductive traces, each extending radially from an inner radius to an outer radius and disposed angularly on one of the dielectric surfaces; and
an interconnect having a starting region, a transition region, and an ending region, the starting region being connected to the outer radius of at least a first conductive trace of the plurality of conductive traces, and the ending region being connected to the outer radius of at least a second conductive trace of the plurality of conductive traces, the interconnect being bounded by an inner edge and an outer edge, and having a first radiused inner edge section extending from the outer radius of the first conductive trace to the transition region, and a second radiused inner edge section extending from the transition region to the outer radius of the second conductive trace;
wherein the interconnect is configured and arranged on the PCS such that a section of the inner edge of the interconnect extending from the connection between the first conductive trace and the starting region to the beginning of the transition region achieves at least 90% of a maximum current density value in the section, as determined by FEA/FEM calculations, within a first 20% of a distance along the section of the inner edge measured from the first conductive trace toward the transition region.
9. The apparatus of claim 8 , wherein:
the PCS comprises a multi-layer printed circuit board, and
the apparatus further comprises a connector that interconnects the second conductive trace to another of the plurality of conductive traces on a different layer of the printed circuit board.
10. The apparatus of claim 8 , wherein the PCS is configured for use as a stator in the motor or generator.