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Gate Driver ICs Forum Discussions

mohammadfarsija
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Hello, I hope you are fine. I am using 2ED300C17-S driver . I have a problem about the Rssd in this configuration. As we know, this resistor is related to soft shot down of the switch and there is an equation to obtain the value of this resistor in data sheet. For my specific SiC module this equation is a negative value and now I don't know this resistor should be zero(short circuit) or infinite(open circuit).

Furthermore , It is important to note that when i assumed the resistor is zero, there is a huge input current of the power supply of the driver(more than 3A ) .

 

I am waiting for your helpful comments.

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AZIZ_HASSAN
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Hi,

To calculate the sense resistor accurately for same driver, I have attached a link which contains the evaluation board of the driver IC and there on page number 11, you can find the formulas and few sample calculation as per different IGBT. 

Secondly, the positing and how to connect the sense pin to switch is simple and straight forward. You can follow the same method to connect the resistor as you do in shunt resistor connection. For connection you can refer to page 14 of the same document.

I hope it clears your doubt. In case you need more clarification, let me know.

https://www.infineon.com/dgdl/Infineon-2ED300E17-SFO_EVAL-ApplicationNotes-v01_01-EN.pdf?fileId=db3a...

BR,

AZIZ HASSAN

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AZIZ_HASSAN
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Hi,

Thank you for posting at Infineon community.

The gate driver which you have mentioned here is not suitable for Sic devices. Please let me know your requirement and application and accordingly we can suggest you a appropriate GD. Or else you can go to the following link and find a suitable GD.

https://www.infineon.com/cms/en/product/power/gate-driver-ics/dual-channel-isolated-gate-driver-eice...

Please let me know if you need any help for selecting a driver or any other calculation.

BR,

AZIZ HASSAN

mohammadfarsija
Level 1
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Thanks for your answer.

Dear Aziz Hassan,

In fact, I have encountered this flow problem when using this driver for the IGBT model IKW40N120T2 .I decided to test this driver for the IGBTs first and after testing it successfully, try it for new switches(my SiC modules).

Do you know what the soft shot down resistance should be for the case of IGBT?

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AZIZ_HASSAN
Moderator
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Hi,

For the IGBT part number shared by you, the soft turn off is not required because this is small package and gate charge is small. As per the calculation, the Rssd is coming negative (because the gate charge is low). So, in such devices soft  turn off is not required (please let me know your system leakage inductance as well to make it more sure).You can go with normal turn off during short circuit.

Even for SIC, the gate charge will be low and also the short circuit time for SIC is low and hence there also soft turn off is not done.

I hope you understood. Please let me know if you have any further doubt.

 

BR,

AZIZ HASSAN

mohammadfarsija
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thanks for your carefully answer.

I did some tests and I will announce the results below. I hope you can help me with the problem.

first test : I set the Rssd resistor to zero and all the output side pins of the driver are active.

result 1: A large current is drawn from the input power supply.

Second test : I set the Rssd resistor to zero and all the output side pins of the driver except "sense pin" are active.

result 2: A large current is drawn from the input power supply.

third test : I set the Rssd resistor to zero and all the output side pins of the driver except "VA-" are active.

result 3: A large current is drawn from the input power supply.

fourth test : I set the Rssd resistor to zero and all the output side pins of the driver except "VA- pin"and "sense pin" are active.

result 4: Input power supply current is normal.

fifth test: I set the Rssd resistor to infinite(open closed) and all the output side pins of the driver except "sense pin" are active.

result 5: Input power supply current is normal and the pulses on switches are ok.

 

best regards.

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AZIZ_HASSAN
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Hi,

Please clarify the following doubts to answer your question.

1) Rssd =0 means  you are shorting the -Va and Sense pins.

2) May I know what do you mean by output pins are active and other pins are not active (please explain 5th point for reference).

mohammadfarsija
Level 1
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Hello dear Hassan,

I hope you are fine.

1.yes.  In my description, Rssd=0 means the direct connection of the sensor pin to the Va-.

2.I tried to figure out which pins at the output belong to the large current drawn from the input power supply. For this reason, I placed some of the pins out of the circuit board so that these deactivate  pins are not connected anywhere.

best regards.

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AZIZ_HASSAN
Moderator
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Moderator

Hi,

Few  IC pins are internally connected to some voltage level directly or indirectly. Lets say 

Va- pin, is used to connect a -16V capacitor. So, when you directly short the pins (Rssd=0), active and deactivate some pins, internally a low impedance path is formed across a voltage level which is causing a huge current flow. Frankly speaking, its hard to tell the exact reason for each test but the reason explained here is a broad answer for your query.

I hope you understood.

BR,

AZIZ HASSAN

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mohammadfarsija
Level 1
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Ok thanks for your helpful comments.

I have an another question . Do you have a good document about connecting sense pin to the switch? 

there is no appropriate explanation about this issue in the documents of  2ED300C17 driver .

as i know there are some ways to connect this pin to the Switch. for example Current Sense Using Shunt Resistor ,Current Sense Using IGBT Vce ,Current Sense Using Shunt Resistor and Negative Gate Drive ,etc.

Which of these methods should I use and how accurately can the values of its resistances be calculated?

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

Hi,

To calculate the sense resistor accurately for same driver, I have attached a link which contains the evaluation board of the driver IC and there on page number 11, you can find the formulas and few sample calculation as per different IGBT. 

Secondly, the positing and how to connect the sense pin to switch is simple and straight forward. You can follow the same method to connect the resistor as you do in shunt resistor connection. For connection you can refer to page 14 of the same document.

I hope it clears your doubt. In case you need more clarification, let me know.

https://www.infineon.com/dgdl/Infineon-2ED300E17-SFO_EVAL-ApplicationNotes-v01_01-EN.pdf?fileId=db3a...

BR,

AZIZ HASSAN

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