IGBT Problem

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moorthi Associate Join Date: Sep 2007 Posts: 26	IGBT Problem 07/15/2009 8:38 AM
	DEAR FRIENDS; am using igbt modules for motor speed control application. To turn ON and OFF gate, i using pc923 ic for switching. +15,gnd and -5 voltage for pc923 ic. It works fine, but rare case gate to collector is short. what will be the reason?
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kvsubramanyam Guru Join Date: Apr 2007 Location: Hyderabad, India Posts: 596 Good Answers: 12	#1 Re: IGBT Problem 07/16/2009 6:13 AM
	Mr.Moorti, The information is not enough. What are the values of biasing resisters of IGBT? What is the IGBT number? PC 923 gives max. 10mA. Is it ok to drive the IGBT? You motioned that IGBT stays turn "ON"; if that is correct you should decrease the values of biasing resistors that try to keep IGBT in "OFF" condition. __________________ Subramanyam
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moorthi Associate Join Date: Sep 2007 Posts: 26	#2 In reply to #1 Re: IGBT Problem 07/16/2009 8:14 AM
	my doubt is, when collector to gate become a short in igbt module?
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redfred Guru Join Date: Dec 2008 Location: Long Island NY Posts: 15600 Good Answers: 981	#3 Re: IGBT Problem 07/16/2009 10:05 AM
	Back EMF is your likely problem. Your motor by definition is an inductive load. If you don't have a planned snubber like current path for when the IGBT turns OFF, the current will make a path one last time through the IGBT. Poof. __________________ "Don't disturb my circles." translation of Archimedes last words
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halcyon_m Power-User Join Date: Jun 2005 Posts: 104	#4 In reply to #3 Re: IGBT Problem 07/17/2009 12:05 PM
	I think you meant to ask if the original poster is using anti-parallel diodes with his modules. If not, obviously that will pose a problem with continuous-current conditions that require free-wheeling of said current.
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CraziestOzzy Power-User Join Date: Apr 2009 Location: Australia, sunny North Queensland Posts: 380 Good Answers: 12	#5 In reply to #3 Re: IGBT Problem 07/18/2009 3:28 AM
	Agreed and good answer, assuming the OP's mentioned driver is suited for the unknown IGBT...I am surprised that the driver does not switch off the IGBT to prevent a potentially damaging short. As mentioned by redfred, you need to solve for an inductive load, which is the motor(?) in your case. The spec sheet for your driver and/or IGBT should have a solution for this...without me even looking. Cheers. __________________ CraziestOzzy
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