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IGBT Failure in VFD
IGBT Failure in VFDs
By M.S.Randhawa on 19 June, 2007 - 6:52 pm

Could you guide us as to what would be the most prominent reason for the IGBT failures in the VFDs and what could be the cheapest solution to be tried out for stopping the Failures?

We have had @ 7 drive failures and we are still in the dark. Even Siemens is not able to help us. These were Micromaster 430/440 VFDs.

Almost 4 Drives are installed in each panel, and we have 4 such panels. Other Panels have 1 or 2 Drives installed in each of them and we have 12 of these.

Thanking you, take care and God Bless.


1 out of 1 members thought this post was helpful...

1) Are the drives fitted with line reactors (chokes) on the line and/or load side?
2) How far away are the motors from the drives? The longer the cable length, the more potential for trouble.
3) Is inverter duty motor cable used between drive and motor (for instance, Belden 295xx series, among other brands)? Is grounding per manufacturer's specifications?
4) What kind of enclosure cooling (if any); what is the drive ambient temperature in the enclosure?
5) What is the line supply (delta or wye?, frequency? voltage?).
6) How are the drives protected (circuit breakers or fuses)? Are these protective devices sized correctly?
7) What is the nature of the mechanical load? Do you use short accel and decel times? Does the drive change output speed relatively slowly over time, or is it swinging speed up and down relatively often, and over a large range?
8) Are the failing drives heavily loaded?
9) Do you get any other types of drive faults (over and under voltage DC link, etc.) and/or performance issues as a matter of course, or do the drives and IGBTs just fail "out of the blue"?
10) Are the failed drives occurring randomly, or do the failed drives cluster around a particular motion axis?
11) What is your switching frequency? A lot of drives default to the 4 to 6 KHz range, and have higher switching frequencies (perhaps up to 20 KHz) as a user option. Higher frequencies tend to lessen motor noise, but at the expense of requiring power bridge derating. Higher switching rates yield more losses >>> higher temperatures.
12) Are you experiencing any unusual motor problems - mysteriously failed windings, or fluted bearing races caused by EDM? See
for info on EDM.
13) Do the drive failure reports point to single IGBT modules failing at a time, or two (or three) for each failure episode? Are their other associated failures (components failing on the DC bus supply?)

I don't have any experience with the Siemens Micromaster drive, and haven't had any noticable trending of IGBT power bridges failing in newer drive designs we do use, so can't give much advice (ask me about 25 year old, "six step" V/Hz drive designs using Darlingtons in the output bridge... these used to blow up on a whim). Generally, though, the things that will kill IGBTs are excessive heat, and excessive voltage (especially low duration, high impulse transients).

It is a good idea to use input chokes, and, with long drive-to-motor cable runs, load side chokes as well.

By Anonymous on 30 June, 2007 - 1:01 am

IGBTs have to be matched. V-Saturation. If paralleled and one IGBT is faster than the other, the faster switching IGBT will carry more load and build more heat and fail.

You may already know that, but I didn't see it in the previous reply. Good luck.

By hiren bhatt on 16 August, 2011 - 8:38 am

IGBT failure mainly because of its igbt manufacturing defects and for that you should shift your igbt rating to next version i.e.if using 70A than shift it to 150A.

1 out of 1 members thought this post was helpful...

CCOMM pretty much covered it all...

One of the few things I can think of on top of the list is...

Is there output contactors on the drives that might be opening up while the drives are running. On a VFD this can cause havoc for IGBTs.

Then again the long list from CCOMM is probably your best starting place...

0 out of 1 members thought this post was helpful...

Hello M.S.

There is a wide range of quality and reliability when it comes to IGBT products. I cannot say why you are seeing a lot of failures. But perhaps a bad mfg run of the IGBT cores could be a potential root cause. In my experience, ABB makes the most reliable VFD's that we have used (fans, pump, conveyors, etc). Perhaps - looking at the IGBT source mfr between Siemens and others will reveal some clues.


By paresh patel on 24 July, 2011 - 10:38 am
0 out of 1 members thought this post was helpful...

Dear Mr Bill,

There are other VFDs which are more reliable where IGBT failure is almost nil. You may try AMTECH ELECTRONICS VFD where there is absolutely zero failure.


By bob peterson on 24 July, 2011 - 12:50 pm
1 out of 1 members thought this post was helpful...

> There are other VFDs which are more reliable where IGBT failure is almost nil. You may try AMTECH ELECTRONICS VFD where there is absolutely zero failure.

Zero failure is pretty impressive. Given that there are only a few companies actually making the IGBTs and all the VFD manufacturers have to use the IGBTs supplied by those manufacturers, how does one VFD supplier manage to get IGBTs that never fail?

what run lengths and HP?

I've also experienced this.

Only one IGBT module connected with the blue phase of the module got burnt, the capacitors of the same phase also got damaged, & and the fuses at the input power supply also burnt away.

Any Idea about the root cause of this.

1 out of 1 members thought this post was helpful...

Ady... if component failure occurs on the same phase, then root-cause is usually related to a parameter (mechanical or electrical) significantly different than those found on the other two phase.

I suggest you start by providing supply-side and drive-side voltage and current measurements!

Regards, Phil Corso

if you have burnt components, you probably have either a power surge or loose screws on a fuse or bus bar internally to the drive.... igbt failure usually doesn't burn/melt components.