how to check a igbt or mosfet devices.when they are connected to the inverter stack (or) any other driver circuit. without disturbing the circuit?

 

Use an octopus.

You can passively look at all the junctions.

 

hai sir
thanks for your reply
The components which he is testing are not connected to any circuit.
My question : let us take any example like 3phase full bridge converter,in that circuit you will have six igbt\mosfet's .
without removing the igbt ,how to check the igbt is working?

 

I am perplexed by your post.

Is the device isolated and out of circuit?

Is the devise mounted in a circuit?

Does the device have power applied?

Does the device power a motor?

Pick one.

 

how to check a igbt or mosfet devices.when they are connected to the inverter stack (or) any other driver circuit. without disturbing the circuit?

I would advise against relying on in circuit testing.

You can test by isolating 2 of the 3 pins, usually most convenient with bolted on power devices.

From drain to source - any leakage whatsoever is a fail, but make sure the gate capacitance is discharged. In fact a slight revision to the procedure - isolate only the drain first and check for leakage, either its leaky or the gate drive circuit is faulty.

Isolate the gate and charge the gate capacitance with a continuity tester - the MOSFET should turn on and stay on until you discharge the gate - if it leaks away; that's another fault mode.

Regular power MOSFETs need about 8V to turn on, the maximum rating can be as low as 15V, so a tester with 12V internal source is usually safe. Some special types like RF can be only a few volts - so don't wade into those without checking the datasheets.

 

The device is non-isolated and fixed inside the circuit

 

The device is non-isolated and fixed inside the circuit

In that case - switch it on and see if it goes bang.