1. Troubleshooting 4-2 MT5F Fuji Electric Co., Ltd. All rights reserved.

Transcription

1 Chapter 4 Troubleshooting 1. Troubleshooting 4-2 MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-1

2 This chapter describes how to deal with troubles that may occur while the automotive IGBT module is handled. 1. Troubleshooting When the IGBT module is installed in an inverter, etc. a failure of the IGBT module might be occurred due to improper wiring or mounting. Once a failure is occurred, it is important to identify the root cause of the failure. Table 4-1 illustrates how to determine a failure mode as well as the original causes of the failure by observing irregularities outside of the device. First of all, estimate a failure mode of the module by using the table when a failure is happened. If the root cause cannot be identified by using Table 4-1, see Fig. 4-1 as detailed analysis chart for helping your further investigation. Table 4-1(a) Estimated causes and its device failure modes External abnormalities Short Arm short- short- Output short- Ground short Cause After short- detection, surge voltage excess SCSO Insufficient dead time dv/dt Noise induced Large t off due to reverse gate bias dead time setting mistakes less reverse gate bias too long gate wiring Gate Logic Faulty wiring, abnormal wire contact, load short- Faulty wiring, abnormal wire contact Device failure mode Outside SCSOA Over heating SCSOA and/or overheat Further checkpoints Integrity waveform of locus and device ruggedness Integrity device t off and dead time Faulty turn-on due to dv/dt Confirm Confirm failure phenomenon Integrity between device ruggedness and protection function Wiring conditions Overload Overcurrent Logic protection function setting fault ing Logic signal Redesign of protection condition DC voltage Overvoltage larger than device breakdown voltage apply between Corrector and Emitter input voltage Overvoltage protection Excess ratings of V CE Redesign of protection condition Destruction due to excessive surge voltage larger than RBSOA at turn-off RBSOA Integrity confirmation RBSOA and operating locus at turn-off Redesign of snubber Overvoltage spike voltage Destruction due to excessive surge voltage larger than device breakdown voltage at reverse recovery Reverse recovery phenomenon at operating with very narrow gate pulse *1) logic or gate due to noise Electromagnetic induction noise from main to gate wiring Overvoltage of V CES Integrity spike voltage and device breakdown voltage snubber Logic and/or gate Mutual interference between gate and main Destruction by the main wiring is too long, the surge voltage at the time of the turn-off to reach the dynamic avalanche voltage Destruction due to dynamic avalanche Redesign of main inductance *1) reverse recovery voltage over device breakdown voltage is produced, if gate pulse width is less than few hundrednano second. MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-2

3 Table 4-1(b) causes of device failure modes External abnormalities Cause Device failure mode Further checkpoints driver supply voltage drop V CE is d by V GE lower than specified value. As a result, power consumption and Joule head are d. DC/DC converter Too much time constant of power supply settling Gate wiring break Each design gate voltage Electro static discharge on V GE Spike voltage larger than V GES is produced by too long gate wiring V GES Assembly area environment against ESD Gate voltage Operation under opened gate Voltage apply to Corrector and Emitter while gate is opened. Gate voltage Overvoltage on diode, sense IGBT Temperature diode and/or sense IGBT destruction due to ESD ESD Assembly area environment against ESD Lack of heat dissipation capacity Anomalous heating due to lack of heat dissipation capacity Less flow rate Radiator Radiation condition or radiation design Thermal runaway Total dissipation is d by carrier frequency d due to logic. Logic on gate Stress Stress Vibration Soldered portion is broken by stress fatigue Stress from external wiring Stress induced vibration Disconnection of Mechanical stress due to mounting condition Reliability (Life time) The application condition exceeds the reliability of the module. Destruction is different in each case. Refer to Fig. 4-1 (a-f) MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-3

4 IGBT module destruction RC-IGBT chip destruction Out of RBSOA A Gate over voltage B Junction overheating C FWD part destruction D Stress destruction E Fig. 4-1(a) IGBT module failure analysis A Outside RBSOA cut-off current turn-on current Over current protection failure short- Gate drive Insufficient dead time Output short- Faulty load Ground fault Faulty load Over voltage supply voltage Faulty input voltage Motor regeneration Faulty regeneration Over voltage protection failure Insufficient snubber discharge Faulty snubber Disconnected snubber resistor Fault time too short surge voltage at FWD reverse recovery D Fig. 4-1(b) Mode A: Outside RBSOA MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-4

5 B Gate overvoltage Static electricity Still no static protection Manufacturing fault Spike voltage Oscillation Gate wire too long L di /dt voltage Gate wire too long Fig. 4-1(c) Mode B: Gate overvoltage C Junction overheating Static power loss Switching loss Saturation voltage V CE(sat) Collector current Switching turn-on loss turn-off loss Thermal resistance Water Over current Over load Turn-on time turn-on current Turn-off time short- Insufficient flow rate of water Clogging of fin Retention of air bubbles Insufficient forward bias gate voltage Over current protection failure short- Output short- Ground fault carrier frequency di /dt Gate drive signal Insufficient forward bias gate voltage Gate resistance snubber discharge current short- Reverse bias gate voltage decrease Gage resistor Insufficient dead time Gate drive Insufficient dead time Insufficient dead time Faulty power supply control Faulty snubber Faulty snubber Pump failure Clogging of pipe failure(water leakage) Degradation of water quality failure(foreign matter) Module installation direction Lower flow late failure (radiator) Fig. 4-1(d) Mode C: Junction over heating MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-5

6 D FWD part destruction of the RC-IGBT junction rise Static loss Overload Power factor drop Switch Switching dv/dt Faulty snubber Gate drive signal carrier frequency Thermal resistance Insufficient water flow rate Pump failure Clogging of pipe Cooling water leakage Clogging of fin Water quality degradation failure(foreign matter) Retention of air bubbles Module installation direction Lower flow rate Water failure (radiator) Overvoltage surge voltage at reverse recovery di/dt at turn-on Forward bias gate voltage Faulty of snubber Faulty of gate derive Decreasing of gate resistor Faulty of gate derive Short off pulse reverse recovery Gate signal interruption by due to noise Faulty of gate derive Faulty of control PCB Fig. 4-1(e) Mode D: FWD destruction MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-6

7 E Destruction due to reliability or product handling Destruction due to handling Reliability induced destruction External force or load tightening torque Insufficient tightening torque for main terminal screws Vibration Impact Soldered terminal heat resistance Storage in abnormal conditions Electric static discharge Cooling water leakage Soaking in high Soaking in low Soaking in high and high humidity Loading during product storage Stress produced in the terminals when mounted Increase contact resistance vibration during transport Loose component clamping during product mounting Dropping, collision during transport ing at terminal soldering Storage in corrosive gas environment Storage in condensationfrendly environment Long term storage in high Long term storage in low Long term storage in high and high humidity Thermal stress fatigue in cycle Long term bias on G-E or C-E under high conditions Voltage applied for long term under hot and humid conditions ΔT vj power cycle ly long screws used in the main and control terminal Storage in dusty environment Assembly at easily charged environment Abnormal at the flange seal Abnormal at the cover of the cooler Abnormal mounting conditions Corrosion Thermal impact by sharp rise or fall in product Long term usage on high Long term usage on high and humidity [Origne of failure] Loading conditions Stress in the terminal section Screw length Clamped section Terminal section Main terminal section Transport conditions Product terminal section Transport conditions Assembly condition at the installation Storage condition ESD control condition at the installation Product handling Product handling water pressure vibration and shock Insufficient torque Broken screw Unsuitable sealing design Unsuitable coolant flow rate Air bubble in the coolant Storage conditions Matching between product life time and operation conditions Fig. 4-1(f) Mode E: FWD destruction MT5F33743 Fuji Electric Co., Ltd. All rights reserved. 4-7