does the arduino have enough current to switch this IGBT ?
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
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.
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.
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
can anyone recommend a transistor ? / Logic level mosfet
To do what?
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"
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.
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.
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)
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 ?
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.
in case anyone is interested
i ended up using an optoisolator and a pull down resistor on the igbt gate
works a treat
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.
the 12v appears to be enough to switch it - so far anyway !
Gadget999:
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.
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 ?