Andrew Cowan
Senior Member
Hi all.
I am building a robot for my AS systems and control project. I am trying to control 36V 750W motors using STP55NF06 FETs (60V, 55A).
I am driving the FETs using a 4427 driver.
The first time I wired it up, the FETs worked fine. The next day when I came into school, both FETs were shorted Drain to Source. I replaced them, and all worked again.
Next time I tested them, I found one was had a 1.5 ohm short between Gate and Source. I replaced them both, and they worked fine.
However, I am now on FETs number 5 and 6. Has anyone got any idea why they are blowing? It was suggested that other students have been turning the motors - but I don't think that this would have damaged the FETs as the FETs are not connected when I leave the robot - they are left as seen in the schmatic below - with no connectors connected. I think this means that even if a voltage was created across the motor, it wouldn't go across the FET.
Any ideas?
Andrew
I am building a robot for my AS systems and control project. I am trying to control 36V 750W motors using STP55NF06 FETs (60V, 55A).
I am driving the FETs using a 4427 driver.
The first time I wired it up, the FETs worked fine. The next day when I came into school, both FETs were shorted Drain to Source. I replaced them, and all worked again.
Next time I tested them, I found one was had a 1.5 ohm short between Gate and Source. I replaced them both, and they worked fine.
However, I am now on FETs number 5 and 6. Has anyone got any idea why they are blowing? It was suggested that other students have been turning the motors - but I don't think that this would have damaged the FETs as the FETs are not connected when I leave the robot - they are left as seen in the schmatic below - with no connectors connected. I think this means that even if a voltage was created across the motor, it wouldn't go across the FET.
Any ideas?
Andrew
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