IGBT - how to do

[Electronics4you]

Hi there

I'm building a hex bridge for a 230VAC induction motor controller for PWM and I can't get the right MOSFETs (very expensive) so I was thinking of IGBTs. I'm new to IGBTs so could someone provide me a circuit that shows how to turn them on and off with TTL or CMOS signals (PICs)?

Are SCRs better or are they too slow switching?
(A circuit for that if it's better)

Thanks

 

[FRIED]

Google 3 phase bridge driver.

 

[Electronics4you]

Ok thanks, but just another thing. I'm driving the 230VAC motor. How can I calculate the IGBT power when the motor is dissipating 5.3A? It's not 230V*5.3A=1219W?

 

[j.p.bill]

You get the spec sheet on the device and see what the on-state resistance is. Use I-squared R to find the power in the IGBT. Allow for several times that because of the transition between saturation and cutoff will cause higher dissipations during the transition.

The manufacturer should have application notes that bear on your questions.

 

[Sceadwian]

IGBT's don't have on resistance, they're BJT's they have a diode voltage drop, they're just driven by a bootstrapped Mosfet. That's why IGBT's are used in high voltage applications because on resistance increases with voltage in a mosfet, which is why IGBT's exist in the first place, the Mosfet drive only has to provide enough curent to saturate the actual drive transistor stage

It really depends on your switching speed requirements.

 

[Electronics4you]

It has to switch at maximum 150Hz

 

[em2006]

To control the speed of a 3-phase motor in open loop, supply voltage and frecquency need to be varied
with constant ratio to each other.

I'm building three-phase induction motor inverter.

https://www.electro-tech-online.com/threads/monolithic-intelligent-motor-controller.28620/

The following link may be util for you:
https://www.electro-tech-online.com/custompdfs/2007/04/MC3PHAC-1.pdf