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Topic: Mosfet for 100V and 15A about 40 KHZ (Read 1 time) previous topic - next topic

leoncorleone

I need a mosfet that can switch about 800 W , 100V and I want to switch by PWM that its frequency is about 40 KHZ.
What kind of mosfet Could I use? Is the "FQP10N60C" good for this?
I want to make a Drive for a BLDC Motor.
Thank you.

saximus

#1
Mar 14, 2017, 06:07 am Last Edit: Mar 14, 2017, 06:08 am by saximus
The datasheet for the FQP10N60C says it has a maximum Rds of 0.73 Ohms. That's atrocious, especially for 800W. At a constant 8 amps (subject says 15 but 800W @ 100V is 8?), it would be dissipating just under 47W but you want to switch it at a very high speed.

Sorry I can't help with an alternate but that certainly isn't your best candidate.

dephwyggl

I need a mosfet that can switch about 800 W , 100V and I want to switch by PWM that its frequency is about 40 KHZ.
What kind of mosfet Could I use? Is the "FQP10N60C" good for this?
I want to make a Drive for a BLDC Motor.
Thank you.
saximus is right about the FQP10N60C; not very efficient. Maybe something like the IRFP250 (30A, 200V, 85mOhm RDS(on)) would be a little better. And, at 40KHz, switching times will play a role no matter which MOSFET you choose.

Cheers!
Dirk

Grumpy_Mike

At those sorts of powers you need both a good FET and a good FET drives you can't just use an Arduino pin and hope to get away with it.

MarkT

I need a mosfet that can switch about 800 W , 100V and I want to switch by PWM that its frequency is about 40 KHZ.
What kind of mosfet Could I use? Is the "FQP10N60C" good for this?
I want to make a Drive for a BLDC Motor.
Thank you.
100V inductive load? resistive load?  What is the max inrush current? 

Why 40kHz - that's pretty high for this kind of voltage/power level and it going to make EMI issues harder
to tame.  The choice of MOSFET is best found by parametric search given the desired specs.

IGBTs are worth considering at this voltage, more robust to large delta-V, although the losses will
probably be higher, and they are usually 600V rating or above so you don't have to worry about
over-voltage spikes or ringing taking them out.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

leoncorleone

Actually it is an inductive load. and the max inrush current is about 25A for 0.2 seconds and then goes to 8A in full load.

MarkT

This one looks promising, although I searched for 200V devices with low on-resistance, http://uk.farnell.com/ixys-semiconductor/ixfh94n30p3/mosfet-n-ch-300v-94a-to-247/dp/2429712

At 8A thats 2W or so, and peaking 20W at turn on.

The high Vds is comforting with inductive loads - how are you taming the spikes on switch-off?  Its
best not to use avalanche break-down in the MOSFET do that job, its a massive rise in dissipation even
if its within the device specs.

I'd sugest a 13V zener clamp across gate and source, a good MOSFET driver chip to drive it with an ohm or two
of gate resistor at most to get fast switching.  EMI and layout will be issues.  A fast opto-coupler might be
a wise precaution (fast here means 10MHz or better logic speed) against catastrophy.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

allanhurst

#7
Mar 16, 2017, 01:32 pm Last Edit: Mar 16, 2017, 01:38 pm by allanhurst
There are other high power components involved which need to be chosen carefully...  and snubber networks may well be required.

eg LT provide lots of data on such applications - try their and other websites.
And the layout of the pcb will be critical - don't even think about a breadboard.

Model aeroplanes etc often use such motors, and it may be easier to buy one of their drivers than homebrew one yourself - there's a signiificant risk of magic smoke in such developments!

Or I bet there are many suggested working designs on model websites to give you a start.



Allan

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