Flux-Switching Machine Based All-Electric Power Train for Future Aircraft

Flux-Switching Machine Based
 All-Electric Power Train
 for Future Aircraft
 Leila Parsa, UCSC
 Project Vision
 To create a lightweight and efficient integrated
 Cryogenic
 motor drive system consisting of flux switching
 machine technology, multilevel inverter and TMS
 combined cryogenic and forced cooling

 Flux Switching Multilevel
REEACH / ASCEND Machine
 Kickoff Meeting
 drive
January 26, 27, 28,
 2021

Fed. funding: $3.392M
 Brief ASCEND Project Overview Length 42 mo.

 Team member Location Role in project
 University of California Santa Cruz (UCSC) Santa Cruz, CA Lead organization
 Air Force Research Laboratory (AFRL) Dayton, OH Team member

 Leila Parsa, UCSC Keith Corzine, UCSC Timothy Haugan, AFRL Christopher Kovacs , AFRL
Context/history of the project
‣ The flux switching machine with HTS field coils provides high power density, robust structure and easier cooling. The
 motor drive technology with WBG devices results in high efficiency and light weight. The integrated thermal
 management system draws on cryogenic and forced convection. The envisioned goal for this project is to explore this
 integrated technology and realize the required power density.

 1

Motor Details
‣ The proposed motor is based on a patented flux‐switching
 design. Additionally, high‐temperature superconducting
 (HTS) coils will be used to set up the field flux.

‣ Both the field and armature windings are contained on the
 stator allowing easier cooling.

‣ Yokeless stator and modular structure are among other
 advantages.

‣ It is anticipated that the power density of the motor
 (without the TMS) will be 20 kW/kg and 125 kW/L.

‣ Finite element analysis (FEA) will be used to verify the
 design.

 2

FSM Principle of Operation
‣ A variable flux path is created due to rotor saliency.
‣ Flux switches direction when the rotor poles cross the field coil.

 3

Motor Drive Details
‣ The drive concept is based on traditional inverter designs, flying capacitor multilevel designs, and cascaded
 multilevel designs. Semiconductor devices are wide‐bandgap featuring low switching loss.

‣ Novel aspects of this design are mostly commercial‐off‐the‐shelf technology and exploring multilevel
 technology to achieve a higher operating voltage and lower operating current.

‣ The power density is above 50 kW/kg and could be higher with an integrated TMS. The efficiency is above
 99%.

‣ Detailed dynamic simulation as well as equivalent circuit analysis is used to establish the design. Future
 development will include integration with the motor FEA analysis.

 4

Drive Study with COTS Components
‣ Three‐level inverter, 52.6 kW/kg
 – Weight, 4.748 kg
 – Junction temperature, 126oC
 – Efficiency, 99.7%
 – Cost of major components, $10,518
‣ Two‐level inverter, 58.8 kW/kg
 – Weight, 4.247 kg
 – Junction temperature, 164oC
 – Efficiency, 99.2%
 – Cost of major components, $5,821

 5

Thermal Management System Details, 0.25 MW Motor
‣ The motor+drive will be fully cooled with bio‐Liquid‐Natural‐Gas (bio‐LNG) fuel; for the stator+rotor ΔT =
 112K  150K, and the Y‐Ba‐Cu‐O superconductor field coils will be cooled to 60K by a proprietary method.
 Exhaust LNG gas from the motor will be sufficient to cool the drive, with ΔT = 150K  300K. The option of
 air cooling is also being considered, and liquid H2 fuel @ 20K is considered viable if preferred, with > 2‐3x
 higher heat capacity than LNG.

‣ Cooling of all heat loads can be accomplished with fuel‐alone, without air cooling. It is considered the
 lowest‐weight/power‐use method of cooling, with minimal added machines.

‣ COP > 100 (vacuum+fluid pumps ~ 200 Watts), LNG or liquid H2 coolant flow rate = 0.2 to 0.6 gallons‐per‐
 minute (gpm), LNG motor‐coolant inlet temp = 112K and outlet = 150K, LNG gas drive‐coolant inlet temp =
 150K and outlet = 300K. Pumps cost ~ $25k (vacuum pump, 1 gpm LNG or H2 fluid pump).

‣ Presently, TMS performance is based on analytical calculations and FEM simulations. A geometrical model
 of the TMS is first created in Onshape CAD software and imported into COMSOL Multiphysics software to
 find heat loads and required cooling.

 6

Thermal Management System Loads: 0.25 MW Motor + Drive

 7

Thermal Management System
 coolant out
 coolant in
 field coil leads

 coolant in/out

 field coil G‐10
 casing

 fiber composite
 wrapping of magnetic
 core encased stator
 winding
 laminated magnetic core
 8

Thermal Management System, Major Heat Sources
‣ Core losses really do not change that much
 extending into cryogenic region
‣ Typical core loss (400 Hz, B0 = 2 T, room temp),
 33.9 W/kg, 0.28 W/cm3
‣ In a Litz cable, the filaments are electrically
 isolated from each other, losses are Eddy current
 losses and transport losses
‣ Eddy current losses (W/m3):
 attainable
 filament
 – where ρ = resistivity, B0 = field amplitude, d size
 = diameter of filament, f = frequency
 – Volumetric transport Losses can be
 calculated from I2R

 9

System Integration Details
‣ Presently, the TMS analysis is integrated with the motor design. Physically, this is made easier since the location of the
 coils yields a better integration to the cooling system.

‣ Project plans include developing a co‐simulation model method for simultaneous evaluation of the motor, electronic
 drive, and thermal management system. Specifically, the integrated design plan includes:

 – Inputting models from motor design, drive design, and thermal management design.

 – Carrying out modeling of the fully electric drive train at the steady‐state cruising condition.

 – Making specific design changes to the motor, drive, and TMS as necessary based on co‐simulation analysis.

 – Carrying out modeling of the fully electric drive train during the transient‐state (take off and climb). Ensure
 operation and evaluate efficiency.

 – Creating a final design of the fully electric drive train.

Initial Risk Assessment

 Almost
 Certain 1 3
 Risk #
 Likely Electronic drive switching
 4 1
 noise
Likelihood

 Thermal management
 Moderate 2
 system
 Electric motor ac power
 3
 Unlikely losses
 2
 Practicality of
 4
 manufacturing
 Rare

 Insignificant Minor Moderate Major Catastrophic

 Consequences

Task Outline & Technical Objectives
Tasks
‣ Design FSM, electronic drive, TMS
‣ Design build, and test motorette and drivette
‣ Manufacture integrated power train prototype
‣ Prepare / execute drivetrain prototype test
‣ Manufacturing and marketing plan

Deliverables
‣ Detailed report on the flux switching motor design including preliminary drawings
‣ Detailed report on the electronic drive including the design details.
‣ A final report of Phase 1 of the project including motor, drive, and TMS.
‣ Generate and deliver report on complete U.S. manufacturing plan.
‣ Report on completed drivetrain with initial testing data.
‣ Complete test report of drive system.
 12

Task Schedule

 13

Technology-to-Market Approach
‣ Potential U.S. manufacturers will be identified for the key components of the drivetrain system.
 Interaction with them will solidify the supply end of the market approach.

‣ The business model for working with manufacturers in the future is based on patenting new
 technology during the ASCEND program and licensing technology thereafter.

‣ First markets will be in the aviation industry.
‣ Envisioned Long‐term markets include power generation and propulsion for electrified
 transportation; specifically, trains, cars, and ships.

 14

Needs and Potential Partnerships
Partnerships

‣ Continuous collaboration/consulting in Phase I with Aveox Inc to transition to building 250 kW
 machine in Phase II

‣ Hypertech Inc, for MgB2 cable consulting and wire/coil purchase, if desired to use low loss 10 μm
 wire; this would be considered if Liquid H2 cooling option @ 20K was considered

‣ Mr. Kevin Yost and AFRL/RQQ Staff, for motorette testing in Phase I

 15

Q&A

https://arpa‐e.energy.gov

 16