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Topic: Can an Arduino switch this IGBT (Read 3481 times) previous topic - next topic

Gadget999

does the arduino have enough current to switch this IGBT ?

http://pdf1.alldatasheet.com/datasheet-pdf/view/217665/SEMIKRON/SKM50GB123D.html

i am struggling to switch it on and off using one of the PWM pins

the arduino shares the same ground as the IGBT

using it to switch a 12V electric motor

madworm

Datasheet, page 1. Look for rCE and the accompanying VGE. You will find that it is quite a bit more than 5V. You will need another transistor to switch it with your microcontroller.
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MarkT

That device needs 15V to drive the gate.  You'll need a transistor to level-shift the logic output from the Arduino up to 15V - also if you want to switch fast the driver should be able to source/sink a fairly large current, perhaps 100 to 400mA.

Do you realize that IGBT are typically more efficient than MOSFETs only for high voltages (200V or more - notice this device is rated at 1.2kV)  This device will lose at least 1 volt when fully on, but a MOSFET could be far better.   Say the load was 10A, then an IGBT would have to dissipate 10W or so as heat, a 0.01ohm MOSFET would only dissipate 1W.

Also MOSFETs are available with logic-level gate drive, which could be more convenient.
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Gadget999

cheers guys - I was suspecting the device needed more than 5v

i have been using a mosfet - but getting it too hot - it has melted the solder !

i will try and get it to switch on and off using the 12V supply and a transistor

can anyone recommend a transistor ? / Logic level mosfet

AWOL

Quote
can anyone recommend a transistor ? / Logic level mosfet

To do what?
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

MarkT

We need to know how much current your motor takes before choosing a MOSFET...   If the motor takes 5A, then a 5A MOSFET is _totally inadequate_  The maximum current rating of a MOSFET is the current at which it _fails_ with a massive heatsink attached!  You always use the R(ds)on figure to choose a MOSFET, never the current rating...

For instance for a 5A motor you want about 0.02 ohm or less MOSFET to keep the dissipation within the ability of a small heatsink.  Actual MOSFETS of that R(ds)on rating are usually rated at 50 to 100A, but you'd never put that much continuous current through them.

And if driving directly from an Arduino pin, it _must_ be a logic-level MOSFET.  That means the R(ds)on figure is given "at Vgs=4.5V"
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Grumpy_Mike

Quote
i have been using a mosfet - but getting it too hot - it has melted the solder !

So what FET was it? I suspect it was not a logic level one and you were operating it in the linear region.

AWOL

Quote
using it to switch a 12V electric motor

I keep saying this (people seem to ignore it), but a slot car motor runs at 12V.
So does the starter motor on my diesel car.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Gadget999

#8
Aug 07, 2011, 11:45 pm Last Edit: Aug 07, 2011, 11:53 pm by Gadget999 Reason: 1
i want a mosfet / transistor to switch the igbt on and off

it will not be switching much load at all

the mosfet i was using was not a logic level type(or so I think and that is why it overheated)

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could i use a pulse transformer driven by the arduino and then connected to the igbt to switch ?

i do not know the current rating of the electric motor, it is not marked with any numbers - it was used inside an electric drill

can you buy boards with optocouplers (for safety) to do this type of switching ?

thanks for the comments and advice

p.s - forgot to mention I have been able to switch the IGBT on and off using my fingers and the postitive terminal on the battery. The datasheet says the VGE = 15V does this mean it will not turn on fully at 12v ?

madworm

That's what the graphs in the datasheet are for. But yes, if it has about 30mOhm at 15V(ge), it will have some more at 12V. Can you tolerate it? Depends on how much power will be dissipated in the device. If you want to play it safe and turn it fully on, you'd better feed it with what it demands. Especially as it doesn't look like a particularly cheap device.
• Upload doesn't work? Do a loop-back test.
• There's absolutely NO excuse for not having an ISP!
• Your AVR needs a brain surgery? Use the online FUSE calculator.
My projects: RGB LED matrix, RGB LED ring, various ATtiny gadgets...
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Gadget999

in case anyone is interested

i ended up using an optoisolator and a pull down resistor on the igbt gate

works a treat

Grumpy_Mike

Quote
i ended up using an optoisolator and a pull down resistor on the igbt gate

That sounds like it is only working by chance if there is not another resistor pulling the gate up to above 15V. A pull down alone will not be reliable.

Gadget999

the 12v appears to be enough to switch it - so far anyway !

BenF


the 12v appears to be enough to switch it - so far anyway !

There are a number of devices that probably would not exist without the IGBT (switched high voltage, high current appliances), but a 12V DC motor doesn't really fall into the IGBT required/desired category. For your application, you may be better off with a MOSFET provided you switch it properly.

To drive an IGBT to anywhere near its capability, a push-pull type driver circuit is needed. Specifications for your IGBT suggest you need +15V to turn it on and -15V to turn it off. This requires a split power supply and you need to source and sink up towards 1.5A (1500mA) to switch it effectively. You could build such a driver from two MOSFET's or BJT's or you can buy a dedicated driver. Experimenting with driving it directly from an Arduino output pin or some pull-up / pull-down scheme to 12V/Gnd is not likely to produce anything useful.

Gadget999

I am going to search for an off the shelf driver

the project will be going to 240 volts in the future - 12v is for experimentation

any ideas who may make such a driver ?

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