Discussion in 'The Projects Forum' started by arunpradh, Sep 3, 2014.
where can i get deeper data about igbt. usually it's switching at higher frequencies
A good place to start is the data sheet for the IGBT you want to use. IGBTs are fairly slow switching as compared to MOSFETs and BJTs.
IGBT and MOSFET related data.
An IGBT is effectively a MOSFET switching a BJT. It's not ideal at high frequencies (like MOSFETs are), but is often used in high-power applications as there is usually less of a voltage drop across the collector and emitter. A MOSFET is an ohmic device, meaning the power that is wasted due to the voltage drop increases exponentially with current (P = I²*R). A BJT, on the other hand, has a fixed voltage drop based on the semiconductor properties (0.7v, for example), so the wasted power is linear (P = V*I) and in high power applications, this is the most efficient.
Please note that this is only a representation, and does not accurately show what the inside of an IGBT really looks like.
An IGBT actually has over a two diode drop which is typically about 2V (as noted here).
I was just using 0.7V as an example because everyone knows that's the diode drop of a regular silicon diode. You're right though, there's more to it than that. Thanks for bringing that up!
Here is something from IR
If I want to using mosfet and bjt to simulate the IGBT in the real world, do you have any suggestions numbers for them?
Use the equivalent circuit that Max showed (with a resistor in series with the BJT base to give a base current 1/10th of the maximum collector current) and add a silicon junction diode in series with the emitter output terminal.
But I was asked for the parts numbers of mosfet and bjt.
That depends entirely on your circuit.
How about for a AC110V 500W application?
The Vce =60V for bjt, Vds=200V for mosfet, those voltages of parts are what I have and usually use.
Well first of all you really should not use BJTs or MOSFETs to switch AC. For that you really ought to use a TRIAC.
You must make sure that the transistor that is carrying the full current can handle it. In an IGBT the main current-carrying transistor is the BJT, so your BJT must be able to handle the full voltage and current that you're trying to switch.
Normally I will use TRIAC, but I'm trying to use a diode has big current and in series with the output of bjt.
If I want to make a dimmer using triac for AC110V/500W , do you have any TRIAC number in hand?
I was thought maybe use parallel method to increase the power, the dimmer I had can be adjust the fan, 100W lamp, 60W solder iron.
I knew that, as I mentioned that the bjt I had only 60V as 2N3055, if I'm trying to use in 200Vdc/2A, 400Vdc/2A, do you have any bjt number to try?
Why I want to try this, because the IGBT is too expensive, so I want to use the mosfet and bjt to simulate.