Difference between dual darlington transistor and dual igbt?

[cnctoolcat]

For the high current types, is there any difference between a dual darlington transistor, and a dual igbt? As best I can tell from the data sheets, the types I am looking at appear to be the same.

 

[ScottyUK]

IGBTs are usually optimised for switching and in pretty big ratings. Their steady state drive requirements are very low although the gate charging current can be significant. Are you looking at a switching application or linear?


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If we learn from our mistakes I'm getting a great education!

 

[cnctoolcat]

I am looking to replace igbt's in a Mitsubishi vfd. Of course Mits wants a small fortune for them. They are 150 amp, 600 volt dual IGBT's.

There are 6 IGBT's on the inverter side of the drive. The inverter igbt's operate in pairs, one pair for each output phase.

The 150 amp IGBT's are driven by a driver circuit up on the control board. Each circuit has a pulse generator chip, a mosfet, a hybrid gate driver ic (a Mits proprietary part), and a diode, working together to drive the base IGBT.

Why are there 12 driver circuits? I am thinking 6 are for motor forward , and 6 for reverse. Of each respective 6, 3 are for accel/run, while 3 are for decel. Is this thinking correct?

I will post a circuit diagram later of the driver circuit. I was hoping you guys could help me with finding a compatible hybrid gate driver ic.

Thanks!

 

[ScottyUK]

Fuji used to make some pretty good IGBT driver hybrids a few years ago. I don't know if these are a current line or not.

As a guess before seeing the circuit diagram, the drivers are either paralleled to boost the gate drive current to achieve a fast switching time, or you have a drive with an active front end rectifier for power factor control or regeneration (or both).


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If we learn from our mistakes I'm getting a great education!

 

[treez]

What is you switching frequency?

that will determine igbt or the darlington

 

[electricuwe]

With the limited knowledge you have on VFD and power semiconductors I would recommend to keep your hands off the part and either consult a qualified repair shop or replace the complete drive.