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“A High Temperature, High Ripple Current DC Bus Film ...

12008 Motor, Drive & Automation 2008 Motor, Drive & Automation Systems ConferenceSystems Conference A high Temperature, high Ripple Current DC Bus Film Capacitor in an Annular Form Factor Presented by:Terry Hosking, EngineeringSBE Ring DivisionFebruary 14, 2008 Atlanta, Georgia2 Areas of DiscussionAreas of Discussion Review 2007 presentation of thermal issues, simulation & testing results Dielectric choices, why polypropylene ? Recent R&D focus on polypropylene film Findings, summary and direction of future work32007 Motor & Drives Review2007 Motor & Drives Review In 2007 we described thermal considerations for using the Power Ring in high Ripple Current inverter applications: Advantages of a thin ring form factor; low losses, low T rise Optimize interface between capacitor and bus structure SBE ssegmented end spray approach to mitigating thermal mismatch of metal end spray and plastic film4 Power Ring s Power Ring s segmented End SpraySegmented End Spray52007 Motor & Drives Review2007 Motor & Drives ReviewFindings, SummaryFindings, Summary Confirmed FLUX 2D simulation with test results: T rise and thermal profiles for various film metallization resistances and cooling conditions 1000 F, 600 VDC unit built and test

“A High Temperature, High Ripple Current ... Segmented End Spray. 5 2007 Motor & Drives Review Findings, Summary ... •Continued research of High Crystalline Polypropylene mechanical and thermal behavior •Interconnect and Packaging options. 31. Thank You! Thank you! Please visit us.

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  High, Current, Temperatures, Polypropylene, High temperature, Ripple, Crystalline, Segmented, High ripple current dc, High ripple current, High crystalline polypropylene

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Transcription of “A High Temperature, High Ripple Current DC Bus Film ...

1 12008 Motor, Drive & Automation 2008 Motor, Drive & Automation Systems ConferenceSystems Conference A high Temperature, high Ripple Current DC Bus Film Capacitor in an Annular Form Factor Presented by:Terry Hosking, EngineeringSBE Ring DivisionFebruary 14, 2008 Atlanta, Georgia2 Areas of DiscussionAreas of Discussion Review 2007 presentation of thermal issues, simulation & testing results Dielectric choices, why polypropylene ? Recent R&D focus on polypropylene film Findings, summary and direction of future work32007 Motor & Drives Review2007 Motor & Drives Review In 2007 we described thermal considerations for using the Power Ring in high Ripple Current inverter applications: Advantages of a thin ring form factor; low losses, low T rise Optimize interface between capacitor and bus structure SBE ssegmented end spray approach to mitigating thermal mismatch of metal end spray and plastic film4 Power Ring s Power Ring s segmented End SpraySegmented End Spray52007 Motor & Drives Review2007 Motor & Drives ReviewFindings, SummaryFindings, Summary Confirmed FLUX 2D simulation with test results: T rise and thermal profiles for various film metallization resistances and cooling conditions 1000 F, 600 VDC unit built and tested 100 KHz/240 Amp RMS test indicated only a +2 C temperature rise, surface to hot spot Test data confirmed modeling accuracy62007 Test Unit2007 Test Unit7So What is Driving the So What is Driving the Choice of Dielectric Film?

2 Choice of Dielectric Film? DoE s FreedomCAR program outlines the demand for low cost, high temperature capacitor technology Upper temperature limit goal of +150 C Rationale for +150 C rating was to use +105 C engine coolant for inverter thermal management, and allow for a +45 C capacitor T rise8 Why polypropylene ?Why polypropylene ? high temperature films are available, but all are EXPENSIVE PPS, 10x the cost of polypropylene , self-healing issue Polyimide, varied electrical performance over frequency and low dielectric strength Teflon, difficult to metallize, has low dielectric strength and is difficult to wind in large capacitor sections In all cases there is a size penalty to pay when compared to Polypropylene9 Why polypropylene ?Why polypropylene ? polypropylene presents best overall value Plentiful, Generally Inexpensive Long proven history of reliability Excellent electrical characteristics The combination of these attributes, and the minimal temperature rise of the ring form factor, has led SBE to further research the limits of Polypropylene10 PolypropylenePolypropylene polypropylene resin is composed of 2 parts: Atactic material which is non- crystalline (amorphous) Isotactic material which is crystalline Highly isotacticmaterial has a higher melting point Highly isotactic polypropylene is referred to as high Crystallinity polypropylene (HCPP) All capacitor grade polypropylene film, including HCPP, is produced by stretching in two directions, BiaxiallyOriented polypropylene (BOPP)11 BOPP vs.

3 HCPPBOPP vs. HCPP HCPP is alleged to have improved performance at high temperature relative to BOPP Does it?12 polypropylene polypropylene CharacteristicsCharacteristics Test data presented here on both BOPP and HCPP for: Dielectric strength vs. temperature Relative leakage Current vs. temperature13 Dielectric StressDielectric Stress Test data for dielectric strength vs. temperature Test data results not as expected! Data taken twice with same results micron film thickness1460070080090010001100851051101 15125 Tem perature (deg C)DC Voltage BreakdownDielectric StressDielectric StressBOPPHCPP15 LeakageLeakage It was expected that HCPP would have lower leakage Essentially no difference, although BOPP was slightly lower16 Relative LeakageRelative Leakage101001000010203040506070809010011 0120130140 Temperature (deg C)Relative LeakageHCPPBOPP11010017 Capacitor ESR at high Capacitor ESR at high TemperaturesTemperatures Capacitor Temperature Coefficient of Resistance (TCR) vs.

4 Temperature TCR is a characteristic of the metallization on the film Relates to ESR increases at higher temperature18 Capacitor Metallization Capacitor Metallization TCRTCR Metallization is Aluminum TCR of bulk aluminum is ~3400 ppm/ C Current flow in a capacitor is across the film (Transverse) Current Flow19 Capacitor Metallization Capacitor Metallization TCRTCR Transverse TCR test data gathered Capacitor-like device constructed to measure TCR using DC source Expected TCR was ~3400 ppm/ C (one would expect ESR to behave the same) SURPRISE, SURPRISE, SURPRISE!! Test data indicates TCR ~80-90 ppm/ C Consistent from run to run ESR will rise less than expected at high temperature20 TCRTCR3040506070809010011012025303540455 0556065707580859095100105110115120125130 135 Temperature (deg C)TCR (ppm/deg C)21 Implications of Test Implications of Test DataData Advancements in quality of base polypropylene resin has closed the gap between BOPP and HCPP as shown by data The form factor of the wound capacitor section has surfaced as a critical parameter in the design regardless of choice of polypropylene grade!

5 22 Capacitor Form FactorsCapacitor Form FactorsToilet PaperPaperTowelPower RingCapacitor end spray surfaceCapacitor end spray surface23 Capacitor End Spray Capacitor End Spray Surface AreaSurface Area1 2 3 Relative surface 1 10 100 Diameter/axial lengthSurface Area vs Diameter/Axial LengthConstant capacitance & film thicknessPaperTowelToiletPaperPower 1 10 Relative 1 10 100 Diameter/axial lengthESR vs Diameter/Axial LengthConstant capacitance & film thicknesToiletPaperPaperTowelPower Ring250 1 Relative distance hot spot to 1 10 100 Diameter/axial lengthThermal path vs Diameter/Axial LengthConstant capacitance & film thicknessThermal Path LengthThermal Path LengthPaperTowelToiletPaperPower RingShortest path to ODShortest path to end spray26 End Spray Surface AreaEnd Spray Surface Area The Thermal Advantage 27 The Thermal AdvantageThe Thermal Advantage Temperature rise of conventional array greater than 5 times that of the Power Ring for a given Ripple Current Power Ring s large, flat surface area allows for greater connection area and short thermal path to heat sink, chill plate, etc.

6 Thus further reducing temperature rise28 Comparative Temperature Comparative Temperature Rise EnvelopesRise EnvelopesTemperature Rise ( C) vs. Ripple Current (Amps) Data assumes both sides of the capacitor held at the same temperature Approximation envelope for conventional array Approximation envelope for Power Ring 29 Findings, ConclusionsFindings, Conclusions No significant performance observed between BOPP and HCPP. DAMN! polypropylene film capacitors will not be rated to operate at +150 C, HOWEVER, the ring form factor improves performance as temperatures elevate Functional upper temperature limit not easily defined, Ring s low T rise allows higher system temperature for a given capacitor hot spot temperature30 Future WorkFuture Work Continued research of high crystalline polypropylene mechanical and thermal behavior Interconnect and Packaging options31 Thank You!

7 Thank You!Thank you!Please visit usin Booth #303


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