– Chapter 7 – Troubleshooting
Contents
1. Chapter 7 Troubleshooting Table of Contents Page 1 Troubleshooting aaa atten eeaaeeeaeeeeeeeeneeeeeee 7 2 2 Failure analysis charts tate taaeeaaeeeeeeeeeeeeeeeeeeees 7 2 3 Alarm factor tree analysis chart gt oo cecccesseseseeeeeeeeeseeeeeeeteeeeeeeeeeenes 7 8 FO Fuji Electric 7 1 Innovating Energy Technology Chapter 7 Troubleshooting 1 Troubleshooting An IPM has various integrated protective functions such as overcurrent protection and overheat protection unlike a standard module It shuts down safely in the case of an abnormal condition However it may breakdown depending on the abnormality of the failure that occurred When the IPM has failed it is necessary to take countermeasures upon clarification of the situation and find the root cause of the breakdown Failure tree analysis charts are shown in Figure 7 1 Carry out the investigation of the failure mode by using these charts For the failure criteria see chapter 4 section 2 IGBT test procedures of the IGBT Module Application Manual RH984b Furthermore when an alarm signal is generated from the IPM investigation of the root cause by reference of the alarm factor analysis chart can be done as shown in Figure 7 2 2 Failure analysis tree charts Deviation from IPM breakdown IGBT breakdown RBSOA specification A Gate overvoltage B Excessive junction temperature rise _ C FWD breakdown D Control circuit E breakdown Reliability F2. breakdown Figure 7 1 a IPM failure tree analysis chart Codes A to F are linked with those indicated in separate FTA pages FO Fuji Electric 7 2 Innovating Energy Technology Chapter 7 Troubleshooting Estimated point of A Deviation from RBSOA specification disorder Excessive Excessive turn off Short circuit between Input signal circuit n h PE A Control PCB disorder breaking current current upper and lower arms malfunction Insufficient dead time Control PCB disorder Output short circuit Load disorder Ground short circuit Load disorder Excessive power f Overvoltage P Input voltage disorder supply voltage Motor regenerative Regeneration circuit running disorder Overvoltage protection se p Control PCB disorder malfunction Insufficient snubber Snubber circuit Snubber resistance discharge disorder open circuit Turn off action at the Gate drive circuit time of short circuit disorder Control PCB disorder Excessive surge voltage at the time of reverse recovery FWD Figure 7 1 b Mode A Deviation from RBSOA specification Estimated point of Gat Ita e overvoltage disorder Control power supply overvoltage Control power supply circuit disorder Excessive power supply voltage Spike voltage Power supply wiring disorder Capacitor disorder Figure 7 1 c Mode B Gate overvoltage Fe Fuji Electric 7 3 Innovating Energy Technology Chapter 7 Troubleshooting Estimated
3. down For results of reliability tests conducted by Fuji Electric see the specification or reliability test report Figure 7 1 g Excessive tightening torque Insufficient main terminal tightening torque Heat resistance of soldered terminals Storage in inferior environment Storage in high temperature conditions shelving under high temperature Storage in low temperature conditions shelving under low temperature Storage in high temperature and high humidity conditions shelving under high temperature and high humidity Chapter 7 Troubleshooting Excessive loading during product storage Excessive stress applied to terminals and case at the time of IPM mounting Excessive stress applied to terminals and case at the time of IPM dismounting Excessive screw length used for main terminals Excessive contact resistance Excessive vibration during transportation products devices Inferior fixing of components at the time of product mounting Falling impact etc during transportation Excessive heating during terminal soldering Storage in corrosive gas atmosphere Storage in condensable environment Storage in dusty environment Long term storage in high temperature conditions Long term storage in low temperature conditions Long term storage in high temperature and high humidity conditions Thermal stress fatigue generated by repeating of gradual up down of product temperat
4. e IPM has stopped and an alarm signal is generated first carry out investigations to identify where the alarm signal was generated from Possible locations are athe IPM or the device control circuit If the alarm was sent from the IPM then identify the factor in accordance with the factor tree chart indicated below V IPM is easy to identify which protective function is activated by checking the alarm pulse width Therefore you can shorten the factor analysis time In addition the alarm output voltage can be easily measured by connecting a 1 3 KQ resistor in series between the IPM alarm terminal and the cathode terminal of the alarming photodiode Phenomenon Alarm factor and method for identification Occurrence of an IPM alarm Normal Overcurrent The collector current is detected by checking the current that flows to the current sense alarm tALM Typ 2 ms IGBT that is built in every IGBT chip The IGBT is OFF for protection if the overcurrent trip level was continuously exceeded for about 5 us Method for identification of alarm factor Observe the alarm and output current U V W using an oscilloscope Observe the alarm and DC input current P N using an oscilloscope Observe the change in the current 5yus before occurrence of alarm output Where a CT or similar is used for current detection check the trip level and point of detection Low control power supply voltage The IGBT is OFF for protection if control power s
5. icient compound weight adjustment Di d cooli Topper Foo ing Clogged heat sink Faulty anti dust measures se capacity Dropped or stopped cooling fan revolution Abnormal rise of i Stack local overheating Cooling system disorder ambient temperature Insufficient tightening torque Insufficient thermal compound weight Cooling fan disorder Figure 7 1 d Mode C Excessive junction temperature rise FO Fuji Electric 7 4 Innovating Energy Technology Chapter 7 Troubleshooting D FWD breakdown Estimated point of disorder Excessive junction temperature rise Increased steady state loss Dropped power factor Load disorder Control PCB disorder Pee Increased Increased switching loss a as switching count Control PCB disorder Input signal malfunction Increased carrier frequency Insufficient element tightening force Excessive fin warpage Insufficient thermal compound weight Input signal circuit disorder Control PCB disorder Increased contact thermal oe Insufficient tightening torque resistance Faulty fin warpage Insufficient compound weight adjustment Dropped cooling capacity Faulty anti dust measures Case temperature rise Clogged heat sink Dropped or stopped cooling fan revolution Abnormal rise of Stack local overheating ambient temperature Increased control power supply voltage Gate signal cracking ca
6. point of disorder C Excessive junction temperature rise rapid temperature rise Increased steady state Increased saturated Gate drive circuit disorder loss voltage VCE sat Control power supply circuit disorder Increased collector Over Short circuit of upper and Input signal circuit current current lower arms repeated short malfunction circuit current Insufficient dead time Control PCB disorder Load disorder Control PCB disorder Output short circuit repeated short circuit current Ground short circuit repeated gece Load disorder short circuit current Control PCB disorder Load disorder Increased i Increased switching j Increased carrier frequency Control PCB disorder loss count Input signal malfunction oscillation Control PCB disorder Input circuit disorder Increased Increased Insufficient control Pannen 3 Input circuit disorder turn on loss turn on time power supply voltage Excessive turn Short circuit between A Insufficient Control PCB disorder on current upper and lower arms r dead time Increased Excessive surge 2 8 Snubber circuit disorder turn off loss voltage _ Input signal Excessive turn Short circuit between circuit off current upper and lower arms malfunction Control PCB disorder ineutncent Control PCB disorder dead time Insufficient element tightening force Excessive fin Faulty fi aul In Wi age warpage z es Insuff
7. t of observation is located nearest to an IPM control terminal Confirm that Vcc lt 20 V dv dt lt 5 V us ripple voltage lt 10 with every one of four power supply unit Confirm that no external wiring connection is made between IPM control GND and main terminal GND If wiring is made noise current flows through IPM control circuit If the drive IC was broken there is a large possibility where the value Icc rises to an abnormal level Example It is abnormal if Iccp 2 10 mA Iccn 2 20 mA and Vin OFF Fe Fuji Electric 7 8 Innovating Energy Technology
8. upply voltage Vcc was of undervoltage trip tALM Typ 4 ms level or less continuously for 20 us Method for identification of alarm factor Observe the alarm and Vcc using an oscilloscope Observe the change in the current 20 us before occurrence of alarm output Chip overheat The chip temperature is detected by the temperature detection element diode that is built tALM Typ 8 ms in every IGBT chip The IGBT is OFF for protection if the TJOH trip level was exceeded continuously for 1 ms Method for identification of alarm factor Measure control power supply voltage Vcc DC input voltage Vdc and output current lo Measure case temperature Tc just below the chip calculate ATj c and estimate the value of Tj Check the IPM mounting method Fin flatness thermal compound etc Erroneous alarm If control power supply voltage Vcc exceeds absolute maximum rating which is 20 V or if Unstable tALM excessive dv dt or ripple was impressed there is a possibility where the drive IC is broken and an erroneous alarm is output Furthermore also in case noise current flows to the IPM control circuit there is a possibility where the IC voltage becomes unstable and an erroneous alarm is output Method for identification of alarm factor A short pulse alarm of an us is produced gt See chapter 6 section 1 2 1 Observe the Vcc waveform using an oscilloscope while the motor is running It is desirable that the poin
9. ure temperature cycle ATc power cycle Thermal stress breakdown generated by rapid rise or fall of product temperature thermal impact Thermal stress fatigue breakdown to product internal wiring etc generated by changes in semiconductor chip temperature caused by rapid load change ATc power cycle Long time voltage impression high humidity impression between C E and between G E in high temperature conditions Long time voltage impression high humidity and high humidity impression THB in high temperature and high humidity conditions Use in corrosive gas atmosphere Long term use in high temperature conditions Long term use in high temperature and high humidity conditions Long term use in atmosphere of hydrogen sulfide or similar Estimated point of disorder Loading conditions Mounting work Forceful dismounting Screw length Torque applied to mounting portion Torque applied to terminal portion Main terminal screw tightening Conditions for transportation Product mounting conditions Conditions for transportation Conditions for assembly during product mounting Conditions for storage Conditions for storage Matching of applied conditions with product service life Mode F Breakdown related to reliability and product handling Fe Fuji Electric Innovating Energy Technology Chapter 7 Troubleshooting Alarm factor analysis tree chart When the system equipped with th
10. used by noise or similar Control PCB disorder Excessive surge voltage at A the time of IGBT turn off E hi t at th f Overcurrent Oe cae nee eet Charging circuit disorder application to converter unit Figure 7 1 e Mode D FWD breakdown Cooling fan disorder Cooling system disorder Excessive surge voltage at the time of reverse recovery Overvoltage Snubber circuit disorder Increased di dt at the time Control power supply circuit of turn on disorder Minor pulse reverse recovery phenomenon Control power supply circuit disorder Fe Fuji Electric 7 5 Innovating Energy Technology Chapter 7 Troubleshooting Estimated point of disorder Control ly circuit Overvoltage Excessive control Ae ve tae a as disorder E Control circuit breakdown Power supply instability power supply voltage Spike voltage Capacitor disorder Excessive power supply wiring length ON OFF of control voltage impression External noise Capacitor disorder Excessive minus voltage Excessive input unit voltage Excessive static electricity External noise Control circuit disorder Insufficient static electricity measures Figure 7 1 f Mode E Control circuit breakdown Fe Fuji Electric 7 6 Innovating Energy Technology F Breakdown related to reliability and product handling External force load Breakdown caused by erroneous handling Reliability service life break
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