Mission Profile Based Analysis Tool for Reliability Studies Ke Ma Ass. Prof. kema@et.aau.dk Center Of Reliable Power Electronics 1 CORPE Annual Symposium / 19 Nov, 2014
Enabling part of design for reliability Typical development cycle of power electronics products Mission Specifications Design & Development Production Specified lifetime Market Unexpected Failures High cost! $$$ Products development considering Design for reliability Mission Specifications Design & Development Production Specified lifetime Market + Expected Failures Reliability Specifications + - $ Much lower cost! Reliability Evaluation Tools A series of evaluation tools for reliability are essential! 2 CORPE Annual Symposium / 19 Nov, 2014
Structure of the tools for reliability Identification Critical components Failure mehanisms Major stress & strength Stress Analysis Mission profile translation Multi-physics stress Multi-time scales stress Reliability Mapping Stress organization Variation & statistics Multi-components system Strength Modeling Component-based Accelerated/Limit test Degradation model Key features: Physics-of-failure based Mission-profile oriented Multi-physics Multi-timescales Reliability engineering-included Reliability Metrics Indirect Thermal loading Voltage/current stress Stress margin Direct Bx lifetime Robustness Reliability/unreliability 3 CORPE Annual Symposium / 19 Nov, 2014
Challenges when considering mission profiles 100 90 75 Voltage(%) Denmark Spain Germany US Limited space 25 0 Keep connected above the curves 150 500 750 1000 1500 Time (ms) Harsh environment Grid faults P Q P Q Wind speed (m/s) Vw Generator side Wind Power Conversion System Grid side Underexcited Boundary P/Prated (p.u.) 1.0 0.8 0.6 Overexcited Boundary 0.4 Ambient Temp. (ºC) Ta Time (hour) Variable wind and temp. All have impacts to thermal cycling and reliability! -0.3 0.2 Underexcited Overexcited Q support Q/Prated (p.u.) 0.4 4 CORPE Annual Symposium / 19 Nov, 2014 4
Thermal stress modelling under multi-time scales Wind speed MPPT Lookup I PV V PV Rectifier D=f(VPV,V dc ) P=f(V PV,I PV ) V dc P V dc P Inverter I load=f(p,q) θ =f(p,q) M =f(l f, V g, θ, V DC) P, Q V g Grid Converter environment 1 year, 3 hours step MPPT Control Inverter Control d boost d inverter LCL Filter Wind speed + - + - Z g Grid Inverter Circuit, generator and grid 3 hours, 1 second step Device and internal structure 0.2 seconds, 0.001 s step 5 CORPE Annual Symposium / 19 Nov, 2014
How the tool works K. Ma, M. Liserre, F. Blaabjerg, T. Kerekes, Thermal Loading and Lifetime Estimation for Power Device Considering Mission Profiles in Wind Power Converter, IEEE Trans. on Power Electronics, 2014. 1.1 kvdc Generator IGBT 690 Vrms Wind turbine Filter Grid 2L converter 2L converter Converter design (Loss curve) Converter design (Cooling and device) Mission profile (solar, wind, grid) Loading Translation P o (t) Loss Calculation P loss Thermal Impedance Rainflow Count N Lifetime Mapping Reliability Metrics Thermal analysis Reliability mapping Consumed B10 life time / year (%) 6 CORPE Annual Symposium / 19 Nov, 2014
A Matlab tool for lifetime evaluation MP inputs 7 CORPE Annual Symposium / 19 Nov, 2014 7
A Matlab tool for lifetime evaluation thermal analysis 8 CORPE Annual Symposium / 19 Nov, 2014 8
A Matlab tool for lifetime evaluation reliability mapping 9 CORPE Annual Symposium / 19 Nov, 2014 9
Test setup for loss characterization Curve tracer for static characterization 50 45 40 35 30 25 20 15 10 5 0 MOSFET Ids-Vds 25 MOSFET Ids-Vds 75 MOSFET Ids-Vds 125 0 1 2 3 4 Double pulse test for switching characterization 10 CORPE Annual Symposium / 19 Nov, 2014
Test setup for thermal impedance characterization Sw. transiant Control/Loss Response v dc* _d d v dc* _i d v dc* _v dc i in _d d i in _i d i in_v dc p loss _ΔT jc Thermal Response Sw. freq. line freq. p loss _ΔT ch p loss _ΔT ha 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 Disturbances Response time ranges (s) happened at 0 s Loss and thermal response time Test setup based on optical fiber thermal meter Loss and thermal impedance characterization 11 CORPE Annual Symposium / 19 Nov, 2014
Test setup for thermal cycling characterization 3L-NPC inverter, 600Vdc, M=0.95, fo=50hz, fs=20khz, Iload=20A max Long term power variation Short term current alternating 12 CORPE Annual Symposium / 19 Nov, 2014
Conclusion A tool for reliability evaluation is basically established. More features are added in, e.g. multi-components, parameters variation More models are being experimentally validated. More mission profiles/applications can be included, e.g. Motor drive. We are open for collaboration! 13 CORPE Annual Symposium / 19 Nov, 2014
Thank you for your attention! 14 CORPE Annual Symposium / 19 Nov, 2014