can traic replace igbt

[garg29]

igbt coast

hi friends
me want to design a ac motor drive.inwhich i want to use traics instead of igbt cause of project cost limitations. will the traic be able to drive the motor with following specifications:

* 3 phase ac induction motor
* 440volts -50 hz
* 960 rpm
*10A

and if yes which traic to use and how?
thank you.

 

[IanP]

Unfortunatelly the answer is NO.
Triacs can be used to turn the motor On and OFF but they are not replacement for IGBTs.

 

[garg29]

I think the triacs can be used for firing angle control for speed control isn't it?

 

[IanP]

That is correct.
In most cases however istead of triacs thyrystors are employed.
It is easy to use this technic on single phase applications.
For 3-phase circuits they can provide smooth proportional control to heaters, furnaces etc (more resistive loads) but I don't think this will be good for 3-phase inductave loads such as motors..
And therefore you have Variable Speed Drives with IGBTs..

 

[nicleo]

... i want to use traics instead of igbt cause of project cost limitations.

Current market prices (quoted from DigiKey):

IRG4PH40K
Category: IGBT (discrete)
Manufacturer: IRF
Specs: 1200V/30A
Price: 5.19USD

30TPS12
Category: Thyristor (discrete)
Manufacturer: IRF
Specs: 1200V/30A
Price: 2.50USD

If you think the difference (5.19 - 2.50 = 2.69USD) is not much, I suggest you to use IGBT.

 

[garg29]

thankyou friendz for replying .ok i agree with you to use IGBTs .now should i use IGBT MODULE (which is very costly) or should i take six IGBTs and combine them.

 

[nicleo]

...now should i use IGBT MODULE (which is very costly) or should i take six IGBTs and combine them.

3-phase bridge inverter could be built using either one of the following configuration:
[1] "Six IGBTs + Six diodes" in single package IGBT integrated module (usually factory-configured as 3-phase bridge)
[2] "Two IGBTs + Two diodes" in single package IGBT integrated module (need three to build 3-phase bridge)
[3] "One IGBT + One diode" in single package IGBT integrated module (need six to build 3-phase bridge)
[4] Six discrete IGBTs + Six discrete diodes

The advantage of using discrete IGBT (i.e. Type [4]) is if one of the IGBTs is burnt, we can replace the burnt IGBT with new one, and keep using the rest that are still in good condition. On the other hand, if we use Type [1] IGBT integrated module, we have to throw away the entire package if one IGBT is burnt. Nevertheless, IGBT integrated module provides great simplicity and save space.

You may consider Type [2] configuration, which uses "Two IGBTs + Two diodes" in single package IGBT integrated module as shown in figure below. The IGBT module shown in the figure is FMG2G50US120 (1200V, 50A) from Fairchild Semiconductor, which quoted at USD30.02 each ( https://www.fairchildsemi.com/pf/FM/FMG2G50US120.html ). To build 3-phase bridge, you need to buy 3 modules.

In my opinion, the difference between the cost of 3-phase bridge inverter built from integrated module(s) (e.g. Type [1], [2], or [3]) and the cost of Type [4] 3-phase bridge inverter is NOT much. However, this comment needs further confirmation. Some 3-phase bridge inverter integrated packages are more expensive because, besides the IGBTs and diodes, they also includes:
(1) Built in brake chopper, 1-phase rectifier circuit, and NTC thermistor (e.g. 600V/30A FMM7G30US60SN from Fairchild Semiconductor quoted as USD138.83)
(2) Built in brake chopper, current sensor, temperature sensor, and driver with overvoltage/overcurrent protection circuit (e.g. 1200V/150A SKiiP 132GDL120-4DU from Semikron)

 

[garg29]

thank you so much nicleo .will use different IGBTs .thats a nice suggestion.will follow that but friend can u tell me which diode to use. the igbt m using is IRG4PC40U.

 

[IanP]

I would rather change from IRG4PC40U to xxxxxxxxD (with internal diode) instaed of spending additional money on external diodes and tasks involved with connecting them...