Confusions about the Safe Operating Area(SOA) of Fast-Recovery-Diode(FRD) of IGBT Module

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Roi_XX
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Hi, happen to encounter the problems about SOA of FRD in IGBT Module.🤣

Thanks for the answers from Infineon’s engineer. I've learned a lot, like    Confusions about the Safe Operating Area of Diodes   & IGBT Module FZ600R12KP4 SOA curve  

  • I saw the FRD-SOA curve on   IGBT Module FZ600R12KP4 SOA curve  (figure 1),from which PQRMM=600kW can be derived. Meanwhile the values on the FZ600 datasheet shows the IRM=590A under the test conditions(VR=600V)(figure 2).
  • To my mind, PQRM is calculated by the transient peak value under the recommended/rated conditions showed on the datasheets, where the Peak Power may should be less than 590A *600V?  However, you can see that the result is quite far less than 600kW from SOA curve. Can the actual Vka(Vce) can rise so high for a large stray inductance or di/dt during reverse recovery?
  •  So is my understanding correct? Whether the test condition to get PQRM is another condition(eg. a limit di/dt for  Dynamic avalanche)?  

SOA.png

PQRM.png

 

 

Looking forward to hearing from you!!!!

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Rachel_G
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Dear  

You can also do Peak power test until device failure depending on the conditions of your application. You can keep the DC bus at the rated value and keep increasing the current and see where is the failure point and vice versa. And di/dt and dv/dt will be determined by your circuit parameters, what is your power loop inductance in all. Along with that the gate resistor (Rgon) and gate voltage (Vge) will also determine switching speed of IGBT and turn-off di/dt of diode. 

For more detail information about PRQM 600kW theoretical calculation, I will discuss with my colleagues and reply you later.

Best regards,

Rachel

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Rachel_G
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Dear   ,

Thanks for your inquiry.

In the SOA diagram, Ir is forward current. In the datasheet, IFRM is 1200A,  which is Repetitive peak forward current. In the datasheet, Irm(590A) is Peak reverse recovery current under the fixed condition which is not related to Ir.  These two parameters are defined differently.

Rachel_Gao_0-1679302376815.pngRachel_Gao_1-1679302403840.png

Vce spike voltage is related to di/dt and inductance of power loop. according to L*di/dt.

Best regards,

Rachel

 

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Roi_XX
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Sorry, I'm still not entirely clear of that.  I mean, it's about SOA of diode and Peak Power of reverse recovery(PQRM).  The reverse recovery process will be focuses, and how safe boundaries  is defined.

It will be nice that you can confirm my questions again! 🤔  Glad to see your reply!

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Rachel_G
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50 likes received 250 solutions authored 250 replies posted

Dear   ,

Sorry to confuse you, let me amend my previous explanation, Ir is diode reverse recovery current in the SOA diagram. 

The SOA of diode is limited by peak current, voltage and peak power. For this device it is 1200V, 1200A and 600kW. So Peak Power of reverse recovery(PQRM) is given in the SOA diagram. In the datasheet, the Peak reverse recovery current will change based upon test conditions, such as diF/dt and Tvj. The datasheet only provides a Irm value under normal test conditions for your reference. And you can also refer to the following chart for diode SOA.

Rachel_Gao_0-1679362684964.png

Best regards,

Rachel

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Highly appreciating your immediate reply, I agree with you very much.👍

So the next & the key is how PQRM=600kW is obtained ? By a DPT experiment under certain conditions or theoretical calculation? Is there an agreed methods or a processes to determine the test condition (di/dt,Vr,etc) for getting the PQRM value?  600*590kW≈300kW(datasheet)   VS  PQRM=600kW, it's hrad to see that how high the Vr(or Vce) or Ir is.🤣

Thank you !I really appreciate this!!

 

Best Regards

 

 

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Rachel_G
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50 likes received 250 solutions authored 250 replies posted

Dear   ,

The 600kW is theoretical value for a 600A devise. We have improved the diodes until they reached the max performance of the rated current. In this case, 600A diodes are installed, so the allowable power is 600kW. And under normal switching behavior it will not reach the 600kW.

Best regards,

Rachel

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Hi  Rachel_Gao:

for a specific diode, the PQRM(Pmax) is an theoretical value determined by design rather than actual experiments?  What is the theory basis?🤔 Can I get the value by test? 

Background is here we have a batch of IFX IHM modules for wind turbine, while the the plastic housing is removed for customization. I guess emmm FZ series. How can I get the SOA of the FWD by testing to set the safe boundaries? For example, maybe I do a DPT for diode under a certain conditions? (under which set conditions: VCC, di/dt, IF, etc.  I can get the PQRM value)  You know in wind application it's severe for FWD. 

Sincerely!  Thank you VERY MUCH. 

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Rachel_G
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50 likes received 250 solutions authored 250 replies posted

Dear  

You can also do Peak power test until device failure depending on the conditions of your application. You can keep the DC bus at the rated value and keep increasing the current and see where is the failure point and vice versa. And di/dt and dv/dt will be determined by your circuit parameters, what is your power loop inductance in all. Along with that the gate resistor (Rgon) and gate voltage (Vge) will also determine switching speed of IGBT and turn-off di/dt of diode. 

For more detail information about PRQM 600kW theoretical calculation, I will discuss with my colleagues and reply you later.

Best regards,

Rachel

Rachel_G
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Moderator
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50 likes received 250 solutions authored 250 replies posted

Dear  

This maximum power (PRQM 600kW)depends on the ability of the diode itself, we have done many tests to verify that it can reach 600w, the specific test conditions are not available to provide customers, you can test the SOA range according to the actual application conditions.

Best regards,

Rachel

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