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MOSFET (Si/SiC) Forum Discussions

KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

Hello Sir,

I have question about IPA60R180P7 double pulse test.

I plan to test Eon & Eoff  and condition as following. 

1. In 130kHz, can not output number 5 pulse to 30A Id current test, but 150kHz can be output number 5 pulse to 30A Id current?  why? 

2. Different frequency with double pulse test whether effect the test result?  

5 cycle and 130kHz&150kHz with 80% duty

CH1 VGS, CH3 VDS, CH4 Id

130kHz

130kHz.png

150kHz

150kHz.png

  

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1 Solution
AZIZ_HASSAN
Moderator
Moderator 100 sign-ins 50 solutions authored 10 likes received
Moderator

Hi,

Thank you for the clarity.

The switches are not smart to stop themselves as per number of pulses or in any condition. They are controlled by gate driver and gate driver PWM is controlled by the microcontroller or any 2 pulse code which you would be using for your test. There could be two possibilities for absence of 5th pulse @130KHz.

1) The code would have a limit of time period beyond which the PWM cant be send (please check weather in your case is it limited to near about 35 microseconds because for 5 pulses @150KHz, the total time is 5*(1/150)= 33.3 usec. and @130KHz, the total time period is 5*(1/130)=38.4usec. So there could be possibility that code is not giving pulses beyond 34/35usec.). This you can even verify by reducing the duty ratio and try to give more number of pulses (don't give pulses that it crosses the max. limit of device current to avoid thermal run away) @ 130KHz .If you are able to give more pulses then its code issue or you can also try to give more number of pulses @150KHz. (keep the device current limit under control) and check weather pulses are going or not. You can even remove the DUT and check the verify the pulses.

2) Check weather you have put any thermal protection based shutdown in device or not. If yes then there could be possibility that the device temperature is reaching to maximum trip level set in the code and hence its stopping the PWM and not allowing the device to switch further. Please let me know if you have put any protection feature other than thermal.

In addition to suggestions given, I have some queries and I request you to clarify.

1) The device maximum continuous current rating is 18A @25 degree (pulse rating is 53 A@25 degree subjected to junction temperature). May I know why you are testing at 30A and  what is your device current requirement as per your actual application.

2) While doing the test what is the junction temperature you are reaching since you are giving more than rated current.

I hope the information is useful to you.

BR,

AZIZ HASSAN

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5 Replies
AZIZ_HASSAN
Moderator
Moderator 100 sign-ins 50 solutions authored 10 likes received
Moderator

Hi,

Thank you for posting at Infineon community.

1)Sorry I could not understand point 1.  Can you please explain it in  more detail.

2) No the switching losses  (Eon and E off for one cycle)and characteristics will not change as per your different frequency as long as you keep your gate resistors and input capacitance same.

 

BR,

AZIZ HASSAN

 

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KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

I would like to understand the Eon&Eoff characteristics of ID current 6A-30A. But it seems that under the condition of 130kHz cycle, when the signal generator drives the DTU through the gate driver, the gate voltage does not output the 5th pulse, which makes it impossible to test the Eon of ID current 30A performance. But under the condition of 150kHz, it can output the 5th pulse to complete tested Eon at Id current 30A.

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AZIZ_HASSAN
Moderator
Moderator 100 sign-ins 50 solutions authored 10 likes received
Moderator

Hi,

Thank you for the clarity.

The switches are not smart to stop themselves as per number of pulses or in any condition. They are controlled by gate driver and gate driver PWM is controlled by the microcontroller or any 2 pulse code which you would be using for your test. There could be two possibilities for absence of 5th pulse @130KHz.

1) The code would have a limit of time period beyond which the PWM cant be send (please check weather in your case is it limited to near about 35 microseconds because for 5 pulses @150KHz, the total time is 5*(1/150)= 33.3 usec. and @130KHz, the total time period is 5*(1/130)=38.4usec. So there could be possibility that code is not giving pulses beyond 34/35usec.). This you can even verify by reducing the duty ratio and try to give more number of pulses (don't give pulses that it crosses the max. limit of device current to avoid thermal run away) @ 130KHz .If you are able to give more pulses then its code issue or you can also try to give more number of pulses @150KHz. (keep the device current limit under control) and check weather pulses are going or not. You can even remove the DUT and check the verify the pulses.

2) Check weather you have put any thermal protection based shutdown in device or not. If yes then there could be possibility that the device temperature is reaching to maximum trip level set in the code and hence its stopping the PWM and not allowing the device to switch further. Please let me know if you have put any protection feature other than thermal.

In addition to suggestions given, I have some queries and I request you to clarify.

1) The device maximum continuous current rating is 18A @25 degree (pulse rating is 53 A@25 degree subjected to junction temperature). May I know why you are testing at 30A and  what is your device current requirement as per your actual application.

2) While doing the test what is the junction temperature you are reaching since you are giving more than rated current.

I hope the information is useful to you.

BR,

AZIZ HASSAN

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KUOWENYUNG
Level 3
50 sign-ins 10 replies posted 5 replies posted
Level 3

Dear Sir,

thanks  for your analyzed and It is very interesting that when I change the VGS voltage from 12V to 13V or replace it with a lower level such as 60R160P7, the 5th pulse can be output at 130kHz frequency.

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AZIZ_HASSAN
Moderator
Moderator 100 sign-ins 50 solutions authored 10 likes received
Moderator

Hi,

OK got it. May i know weather you the test which I requested in my earlier comments. It will help us to debug the cause. If yes, please share the result.

BR,

AZIZ HASSAN

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