Integration of Novel Flux Coupling Motor and

Current Source Inverter Burak Ozpineci

Oak Ridge National Laboratory May 16, 2012

Project ID: APE034

This presentation does not contain any proprietary, confidential, or otherwise restricted information

2012 U.S. DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

2 Managed by UT-Battelle for the U.S. Department of Energy

Overview • Start: October 2010 • End: September 2015 • 36% complete

• Barriers addressed – High permanent magnet (PM) cost for motor – Bulky and costly DC link capacitors for VSI – Bulky and costly DC link inductor for CSI

• Total project funding –DOE share – 100%

• Funding received in FY12 –$550K

Timeline

Budget

Barriers

• Work with SMC vendor on optional core material

• ORNL Team Members: John Hsu, Lixin Tang, Randy Wiles, Gui-Jia Su

Partners

VT Program Targets addressed • DOE 2020 Drive System Power Density

Targets – 1.4 kW/kg – 4 kW/l

• DOE 2015 Drive System Cost Target -- $12/kW

3 Managed by UT-Battelle for the U.S. Department of Energy

Relevance

Objectives: To integrate a non permanent magnet (PM) electric machine and a current source inverter (CSI)

• minimizing capacitors in inverters • eliminating rare earth materials used in traditional traction motors • eliminating the DC link inductor in the CSI through utilization of the leakage flux linkage in the motor

Meet the DOE 2020 drive system targets of

1.4 kW/kg, 4.0 kW/L, and the DOE 2015 cost target of $12/kW

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Milestones FY11 • Perform electromagnetic computation and finite element analysis (FEA)

toward a design suitable for a proof-of-concept prototype and conduct tests.

• Go/No Go decision: The feasibility for integration will be judged by sufficient leakage inductance for the CSI and the blocking of the AC flux going into the rotor of the motor.

FY12 • Optimize design for prototype motor and prototype inverter. • Go/No Go decision: Determine if the optimized motor and inverter

designs can meet the objectives.

FY13 • New motor core and coil design and simulations. • Improved system control study. • Partial component tests. • Go/No Go decision: If simulation and partial component tests show

that the cost of system and the performance are better than those of the separated old arrangement.

5 Managed by UT-Battelle for the U.S. Department of Energy

Approach/Strategy • This project builds upon previous R&D accomplishments

– ORNL CSI research has demonstrated capacitance reductions of 90%

– ORNL Novel Flux Coupling Machine Without Permanent Magnets provides IPM like performance using no PMs

• Approach integrates the two technologies and uses inductance from the motor to replace the CSI inductor – Reduces weight and volume (inductor largest and heaviest

component in CSI) – Reduces cost

• This totally new concept involves technical challenges in ability to manipulate and successfully separate the motor coil flux components

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Description of Technology/Approach • The concept depends on the ability to utilize the excitation

coil in the motor to function in two roles. In addition to providing motor excitation it will also function as an inductor for the CSI.

Stationary excitation coil

within the NFC Current Source Inverter Novel Flux Coupling Motor

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Example for Blocking High Frequency Flux

Leakage inductor carries most AC flux.

Iron path inductor sees most DC flux due to shunt wound coil blocking.

Shunt wound coil acts as a high frequency blocking coil for preventing flux going into rotor.

Insulated iron wires compressed with insulated soft magnetic powders

Blocking high frequency flux going into motor rotor is an on-going research work.

Stationary excitation core

Rotor

Shorter and mainly air

magnetic paths

Longer and saturated magnetic path

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High frequency blocking coil, or controllable shunt- wound coil.

time

Current

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Current

DCAC

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Accomplishments to Date

In 2011, we •Completed the FEA simulations of the NFC

motor and locked-rotor tests, •Designed and fabricated a iron-wire excitation

core that can take high frequency for the integration project,

•Tested the prototype core with inverter, and •Validated the integration concept. • Initial tests showed poor coil efficiency leading

to lower than desired overall efficiency.

9 Managed by UT-Battelle for the U.S. Department of Energy

Accomplishments to Date - Experimental setup of integration of NFC motor and CSI

Excitation Core of NFC Motor

CSI

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The Integrated System - Locations of Vdc2 and Vdc

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Accomplishments to Date Tested Input current (100 A/div), two output voltages (500V/div), two output currents (50A/div) and input voltage (500 V/div)

With the NFC-Motor excitation coil inductor With a separate CSI inductor

IL 100 A/div

Vac Vbc 500 V/div

Ias Ibs 50 A/div

Vdc 500 V/div

IL 100 A/div

Vbc Vca 500 V/div

Ias Ibs 50 A/div

Vdc 500 V/div

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Accomplishments to Date - Power electronic system (excluding load) efficiency with different DC bus inductors

40

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60

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100

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

Effic

ienc

y (1

00%

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m =

With NFC motor coil

With a separate CSI inductor

With NFC motor coil as theinductor and Short Circuit ring

Modulation index= V_dc2/V_dc

PE

S E

ffici

ency

(%)

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wr

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S12S11

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S32S31S22S21

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Accomplishments in FY12 Diagram of the simulation model in PSIM

2. Current source inverter(CSI)

1. DC/DC interface

3. NFC motor.

4. CSI controller and gate pulse generator.

5. DC/DC controller.

14 Managed by UT-Battelle for the U.S. Department of Energy

Accomplishments in FY12 Simulated Input current (100 A/div), two output voltages (500V/div), two output currents (50A/div) and input voltage (500 V/div)

0.05 0.06 0.07 0.08 0.09 0.10-150

-100

-50

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Time

I DC 100 A/div

VL-L 500V/div

I 50 A/div

Vin 500V/div

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-600

-500

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-200

-100

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100

0.05 0.06 0.07 0.08 0.09 0.10-150

-100

-50

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Time

I DC 100 A/div

VL-L 500V/div

I 50 A/div

Vin 500V/div

-700

-600

-500

-400

-300

-200

-100

0

100

With the NFC-Motor excitation coil inductor With a separate CSI inductor

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Collaborations

Depending on success, in FY 12 discussions will be held with soft magnetic composite manufacturers for excitation core materials.

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Future Work FY13 • Motor core and coil simulations and partial component tests.

FY14 • Prototype design and fabrication of the newly designed

integrated system.

FY15 • Test the prototype and report the results.

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Summary

• Previous R&D has demonstrated;

• CSI reduces bulk capacitance requirement by 90%; inductor in CSI is heaviest, largest single component.

• Novel flux coupling motor yields IPM-like performance using no PMs

• This project integrates the two technologies and uses the motor coil to replace the CSI inductor.

• Concept expects to meet DOE 2020 system weight and volume targets and 2015 system cost target.

• Initial calculations indicate that the excitation core of the novel flux coupling motor can produce sufficiently high inductance to meet the inverter’s PWM and boosting needs.