In-situ Health Monitoring for Power Electronics Modules Prof V Pickert, Dr B Ji Newcastle University Pictures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Motivation Pictures Picture Source www Engine Management Light NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Background Improve Reliability/ Availability/ Safety Condition Monitoring Diagnostic Lifetime enhancement Health Monitoring Lifetime Estimator NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group Redundancy Fail Safe/ Fault Tolerance 20.02.2014 Diagnostic Condition Monitoring System is constantly monitored through diagnostic tools Health Monitoring System is constantly monitored through diagnostic tools and compared with its infant state Lifetime Estimator System is constantly monitored through diagnostic and prognostic tools NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group Part is replaced when it fails Part will be replaced after a warning has been issued Part will be replaced to the most convenient time 20.02.2014 Change in failure rate over time Failure rate early failure period random failure period wear-out failure period condition based Condition monitoring maintenance normal operation Health Monitoring diagnostic and & prognostic Lifetime Estimator end of life time NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Condition monitoring Simple condition monitor tool Pictures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Lifetime estimator Data Acquisition Data Manipulation State Detection Health Assessment Prognosis Assessment Advisory Generation NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Health monitoring • Measures the status of health of a component. • Compares health relevant parameters with a baseline. • The baseline is is seen as the ideal (or healthy) parameter. • The difference between the measured value and the baseline is called degradation or ageing. • “Health risk” is identified if degradation becomes too large. NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Advantages of health monitoring Car on crossing • Safety is improved because a warning is flagged up prior failure Car in garage at convenient time • Availability is increased through maintenance scheduling Garage reads out failure code before failure occurs Parts are changed based on their health not OEM recommendation • Reliability is increased through collecting information on degradation • Reduce maintenance cost NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Health monitoring techniques Model-based method Mission Profile Parameter Extraction Physics of failure model Counting Algorithm Fatigue Accumulation Data driven method Pictures Static / Right-Portable power module health characterisation tester Fusion method combination of both NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 In-situ health monitoring technique Health monitoring in real time proposed by researchers from Newcastle University Pictures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Power converter system failure distribution Power device failures 31% 2. “An Industry-Based Survey of Reliability in Power Electronic Converters”, IEEE IAS, 2011 NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Standard IGBT module packaging and main failures Cover Terminal Bond wire Silicon chip Isolation substrate with copper foils on both side Silicon gel Epoxy Base plate (Copper) Two major failure modes: 1) bond wire failure 2) solder fatigue ∆l = CTE ⋅ ∆T l A power module fails due to temperature swing NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Temperature cycling induces stress symbol type causes features ∆Tj active power cycling Power dissipation within semiconductor chips Short cycling period, larger temperature gradient from chip to cooling plate ∆Theat sink passive thermal cycling Operational environment changes (e.g. ambient temperature, coolant temperature, etc.) Long cycling period, large variation, identical temperature excursion Pictures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 How to measure temperature? Direct measurement Pictures Indirect measurement Temperature Sensitive Electric Parameters: e.g. VCE(on) and VGE(th) NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 VCE(on) as a temperature sensor C 140 G positive temperature coefficient 120 100 E IC [A] SIG C 158 T120 R3 80 ① negative temperature coefficient 40 20 25°C 75°C 150°C 0 0 500 1000 VCE [mV] 1500 2000 forward voltage drop 60 -2mV/K ③ ② 25°C NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 125°C X°C virtual junction temperature 20.02.2014 VCE(on) also helps to measure bondwire resistances Vchip RKK’1 L1 RL1 Vchip RMA1 RAA’1 RKK’2 RMA2 RAA’2 RCu RL12 RCu RCu RCC’1 RME1 RG1 REE’1 RE1 RCu RL3 RCu RL2 L2 RCC’2 RME2 RG2 REE’2 RE2 L3 VT NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group VT 20.02.2014 Bondwire degradation Pictures VCE(on) increase NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Solder Aging Test and Analysis 1. Accelerated aging test with air-toair thermal shock chamber 2. Evaluate solder layer conditions with SAM Pictures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Experimental Results Sample 1 Sample 2 IR camera 0 cycle 97.37% 98.29% 98.74% 99.08% 89.32% 74.79% 86.86% 800 cycles 74.52% 1300 cycles 59.75% 73.88% 61.72% 71.6% NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 In-situ health monitoring circuit T3 D1 n io t c e t o r p M T2 D6 n io t c e t o r p e iv r d e t a G n io t c e t o r p e iv r d e t a G Measurement with digital isolation (optical and inductive) e iv r d e t a G e iv r d e t a G & & & T6 D4 6 D5 D2 n io t c e t o r p n io t c e t o r p e iv r d e t a G T4 T5 e iv r d e t a G CDC D3 n io t c e t o r p & & VDC & T1 Selector relay network 5 100mA D Aux. Auxiliary switch 1 Gate drive Controller Relay signal High current SPI Digital isolation 6 Inverter T1~T6 ISO0 PSU NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Digital isolation and protection circuit DC/DC +VISO +VISO REF BANK2 Voltage VISO ISO1 Reference +VISO Voltage -VISO REF ISO2 ISO1 Reference ISO2 10uF ISO1+VISO 10uF 100nF ISO2 A1 +VISO ISO1 ISO2 -VISO Z D 100nF ISO1REF ISO2 -VISO1 ISO R2 +VISO -VISO REF ISO1 VCC VCC DC/DC REF VDD VIO ISO2 SCLK REF VDD VIO A1A/D SDI A2 Converter A2 SDO SCLK A/D CSSDI A3 A4 ConverterSDO A3 A5 GND CS A6 ISO1 GND VCC Digital isolator IA OA Digital OB Isolators IB IC OA OC IA OD OB ID IB IC OC ID OD R1 SCLK DO DI CS0 VEE MCU CS1 ISO (a) up to 600V BANK1 VCC BANK2 Characteristics: based on digital isolation 16-Bit analog differential input 125k samples per channel per second bank isolated isolated from earth ground multiple gains NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group DPST (NO) VEE ISO (b) 600V-2500V 20.02.2014 Generating the baselines for bond wire failures NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Operation detecting bondwire failure 300us 100us Measurement delay time Ih Il (100mA) time VCE(h) VCE(l) time VCE(h): Voltage drop with high current VCE(l): Voltage drop with low current The high current Ih is used to measure the voltage drop and the low current Il is used to measure the temperature using TSEP. NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Results IGBT with broken bond wires: Total failure with 2 broken bond wires Pictures FWD with broken bond wires: Voltage increases by approximately 12mV for the IGBT and 7mV for the diode with one bond wire lift while the resolution for the proposed in-situ measurement circuit is 1.2mV NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Solder fatigue results into higher chip temperatures 100% 81% 64% 49% NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Operation Thermocouple at baseplate TSEP Z thjr (t ) = T j (t ) − Tr (t ) P 1 Pav = N Itest+Isense current N ∑V CE ( on ) (u ) ⋅ I C (u ) u =1 1 ms Test pulse about 1 ms Duty Ratio = 94.4% Isense (100mA) time VCE(h) VCE(l) time VCE(l): Voltage drop with sense current (before test pulse sequence) NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group VCE(l): Voltage drop with sense current (during test pulse sequence) VCE(h): Voltage drop with heating current (during test pulse) 20.02.2014 Summary • Introduction to health monitoring for power electronics • In-situ health monitoring is operating in “real-time” and can be embedded in EVs/HEVs • In-situ health monitoring can be applied to other packaging technologies • In-situ health monitoring can be applied to other power electronics devices such as capacitors for example • Received funding from KTP/TSB to increase TRL level • Received Faculty Innovator Award NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014 Thank you everyone! Prof V Pickert, Dr B Ji Newcastle University Email: [email protected] NEWCASTLE UNIVERSITY Power Electronics, Drives and Machines Research Group 20.02.2014
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