Discussion in 'Homework Help' started by jm-a, Dec 5, 2010.

1. ### jm-a Thread Starter Active Member

Oct 20, 2010
105
2
Hi,

I have a few questions about igbt module, if someone could reply, it would be great

Data about components to check my values:

BSM10GD120DN2 ( igbt module from eupec )

DC Collector current T°c= 25 ° Ic=15A
T°c= 80°c Ic=10A

Vge Threshold 5,5 V typical
4,5 V mini

Pulse collector current tp=1ms 30A for T°c = 30A
20A T°c = 80°

FOD3120 ( optocoupler from Fairchild )

" Absolute Maximum Ratings " Io Peak Peak Ouptut current 3A

MEA1D1509SC ( dc/dc converter )

Output 18V and +- 56 mA

First question:

Gate Resistor Value ( From AN 7003 p6/10 Gate resistor-Principles and application )

Rg mini = ( Vg on -Vg off ) / IGm

Vg on = 18V
Vg off = Threshold voltage for BSM10GD120DN2 is about 4,5V mini, so my choice is 4V . Right or wrong ?

Io Peak Maximum Current for FOD3120 is 3A

Rg mini = ( 18 - 4 ) / 3 ≈ 5 Ω Right or wrong ?

Second question:

Now i need to power an inductive load ( brushless ) with 5A average current.

First: check if V positive rail is about 0,8 Vce in maximum ratings.

Then rough estimate: surge current is about 6 x average current, so I must see Pulsed collector current in the data.

Value is about 30A, so it's ok. Right or wrong?

I only want to know if surge current time is generally , in 1 mS or more?
Any idea?

Third question ( Extracted from Fuji IGBT module application manual p 22 /95 )

" On an installed IGBT , if the gate circuit is faulty or inoperative ( while the gate is open ), the IGBT may be destroyed when a voltage is applied to the main circuit.

In order to prevent this destruction, it's recommended to add, between gate and emitter:

- resistor Rge
- diode - avoiding overvoltage, i think ? - and how to choose this component ? TVS bidirectionnal diode or other?
- capacitor value of 10 % of Cge

One more thing i don't understand, these added components are mandatory in all design cases or only for " pcb + wire feed " ------> IGBT bricks?

Is it the only way to do the job ?

Thanks a lot.

jm

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Last edited: Dec 5, 2010