Hi Sir,

I need some help as I'm facing a MOSFET over heating problem. I'm working on a H bridge design, in which I want to use P(IRF4095) and N(IRF1010E) type MOSFE'S to change the polarity of a peltier. The problem now is that whenever I try to operate the H bridge with giving PWM input signals, the N(IRF1010E) type MOSFE'S temperature rocket climbs and it becomes even impossible to touch it. Mosfet is supposed to be able to handle 60Vand 84amps, and I am "only" using 12v, 15Amps.
So, is it normal for a power mosfet to get this hot?

i have attached the circuit diagram.

 

Welcome to AAC!

So, is it normal for a power mosfet to get this hot?

No. What are the threshold voltages for the MOSFETs? What are the voltage levels of the PWM? Is there any overlap between the signals?

 

Do you have your MOSFETs on a heatsink?

 

Thanks for your reply sir,
threshold voltages for the MOSFET VGS(th) = 2 to 4v
voltage levels of the PWM (GATE VOLTAGE) =12v
currently i can't changed the polarity, i am testing for heat signal only (Q1 and Q4 - continuously on) and (Q2 and Q4) not used, so not overlap between the signals

 

Do you have your MOSFETs on a heatsink?

yes sir

Welcome to AAC!
No. What are the threshold voltages for the MOSFETs? What are the voltage levels of the PWM? Is there any overlap between the signals?

View attachment 284618

Thanks for your reply sir,
threshold voltages for the MOSFET VGS(th) = 2 to 4v
voltage levels of the PWM (GATE VOLTAGE) =12v
currently i can't changed the polarity, i am testing for heat signal only (Q1 and Q4 - continuously on) and (Q2 and Q4) not used, so not overlap between the signals

 

Also…Is there a load drawing current at the moment, and
can you confirm by looking at gate-source voltage of each MOSFET that only one MOSFET on each side of the bridge is on?

What is the thermal resistance of the heatsink?

 

Also…Is there a load drawing current at the moment, and
can you confirm by looking at gate-source voltage of each MOSFET that only one MOSFET on each side of the bridge is on?

What is the thermal resistance of the heatsink?

load side I connect the peltier, and checked gate-source voltage (12v) and also I removed the Q2 and Q3 MOSFET'S , Q1 and Q4 MOSFET'S only connected , Q4 mosfet's only over heating.

 

Edit:
What is the thermal resistance to ambient rating of your heatsink?

Have you measured any temperatures? Transistor case, heatsink, air?

 

I measured the temperature using thermometer, heatsink temperature 80 °C and mosfet case temperature 83 °C and i don't know the thermal resistance of the heatsink.

 

I want some h bridge safety features sir , if one of the mosfet failure, how to product the other Mosfet's and load modules?

 

The IRF1010 MOSFET has a on resistance of 0.012 ohms. The current now is 15A. Thats 2.7 watts. With no heat sink that is very hot.
I cannot find data on the other MOSFET.

 

Hello,

@ronsimpson , Here are both datasheets.

Bertus

 

[QUOTE="Kumar san, post: 1790301, member: 897179 , Q1 and Q4 MOSFET'S only connected , Q4 mosfet's only over heating.
[/QUOTE]
Sounds like Q4 is not fully ON and operating in the linear region. Check the voltage on the drain of Q1 and Q4

 

Here is how to tell if the part is turned on well. Or use a meter. lol
Two graphs. 25C and 175C.
The left two curves are for 15V and 10V Gate to Source voltage. So you can guess where the 12V curve is.

 

The graphs in a datasheet are for a "typical" one that you cannot buy. Your Mosfet might have a minimum current when it has a maximum gate-source voltage.
Maybe you have its pins swapped? G D S.

 

what is pulse rate? those are pretty large transistors with massive capacitance of some 3500pF each. so one output rated to drive 1000pF load is driving 7000pF...? the driver may be underrated. did you check manufacturers application notes?
https://ww1.microchip.com/downloads/en/Appnotes/00786a.pdf

 

Hi sir, its working well, but sometime's P or N type mosfet failured. pls verified the circuit sir?