Ultra-Compact Electrical Machines for Wind Energy DE-FOA : Demo Machine C. L. Goodzeit and M. J. Ball May 1, 2014 Part 1: Design and Construction 5/1/2014 V11

The dual armature machine uses an armature comprised of two concentric armature windings with a radial space between them sufficiently large to enclose a field source. Thus the armature links flux from both the inner aperture and outer volume of the field source, typically increasing the total armature flux linkage by a factor of two with the same sized machine. This typically provides equivalent power with only 50% of the field material used for a conventional machine of the same size. This is also an increase of a factor of two in power density. The proposed fully superconducting dual armature generator is a 6-pole machine with a stationary field coil and both the inner and outer armature coils on the rotor. The field coil will be 300 mm in length with a nominal aperture of 300 mm. The dual armature machine uses an armature comprised of two concentric armature windings with a radial space between them sufficiently large to enclose a field source. Thus the armature links flux from both the inner aperture and outer volume of the field source, typically increasing the total armature flux linkage by a factor of two with the same sized machine. This typically provides equivalent power with only 50% of the field material used for a conventional machine of the same size. This is also an increase of a factor of two in power density. The proposed fully superconducting dual armature generator is a 6-pole machine with a stationary field coil and both the inner and outer armature coils on the rotor. The field coil will be 300 mm in length with a nominal aperture of 300 mm. 5/1/2014 V12

3 Legend: 1. Outer armature coils on rotor 2. Inner armature coils on rotor 3. Field coils 4. Mechanical support for field coils 5. Dual armature torque tube (part of the rotor) 6. Alignment bearings (support for the field and armature coil free ends) 7. Low heat leak stand offs 8. Low heat leak splined shaft connecting torque tube to external environment 9. Instrumentation and power leads for the armatures 10. Field coil current leads 5/1/2014 V1

4 Supercon very small filament (VSF) NbTi wire

5 2- layer center wound coils Contact tooling inner radius = ~150 (inner coils) Contact tooling inner radius = ~170 (outer coils) 12 segments required for demo machine Typical Coil Winding and Impregnation (Flat Coil Example) 5/1/2014 V1

6 Automatic winding machine (Direct Wire Method). 1 mm diameter 7 strand cable (shown on slide 4) applied directly to a composite cylinder. (3-phase coils)

5/1/2014 V17 Current, ACoil Type Num. layers Num. strands Num. turns / segment Strand dia. Ins. thick. Cable thick. Cable width Radius (inner) 2000Field Field Ph a: inner Ph a: outer Ph b: inner Ph b: outer Ph c: inner Ph c: outer Field and Armature Sextupole Coils

5/1/2014 V18 Step 1: Arrange coils without pole pieces on the inside diameter of cylinder with insulation and wedges as shown. The azimuthal angle of the coils should be such that they all fit against the cylinder with thin G10 shims between them, if necessary so they are not loose. Step 2. Wedge shaped steel pole pieces are then inserted so that they start to engage the pole slot in each coil segment and the screw holes line up with those in the cylinder. Step 3. Insert loading screws and tighten them all in sequence so that the pole pieces are drawn into the pole slots and compressed azimuthally.

5/1/2014 V19

10

5/1/2014 V1116/9/2011-V111 Implemented by BNL in Armature Coil Windings 5 required per armature, i.e. 10 total installed

5/1/2014 V112 The inner and outer armatures are provided with small embedded temperature sensors (Lakeshore CERNOX) that are relatively insensitive to external magnetic fields. These sensors are obtained calibrated by the supplier and accurate to ±5 mK. Thus accurate measurements of the temperature difference between the armature coil conductor interior and exterior surfaces will be used for computing the dissipative energy produced in the armature coils under various conditions. The transport current to be applied to the armature coils is limited to 30 A, due to the rating of the Mercotac connector current leads. The transport current increases the hysteresis loss. Thus, up to 30A armature current will be used as part of the test program to determine whether the temperature gradient measurements reveal an initial slope for increased hysteresis loss due to the transport current effect. The inner and outer armatures are provided with small embedded temperature sensors (Lakeshore CERNOX) that are relatively insensitive to external magnetic fields. These sensors are obtained calibrated by the supplier and accurate to ±5 mK. Thus accurate measurements of the temperature difference between the armature coil conductor interior and exterior surfaces will be used for computing the dissipative energy produced in the armature coils under various conditions. The transport current to be applied to the armature coils is limited to 30 A, due to the rating of the Mercotac connector current leads. The transport current increases the hysteresis loss. Thus, up to 30A armature current will be used as part of the test program to determine whether the temperature gradient measurements reveal an initial slope for increased hysteresis loss due to the transport current effect.