Tanna Posted May 25, 2007 Report Share Posted May 25, 2007 Hi.I'm trying to PWM a hobby-motor running on 9.4V.I'm using i PIC with a BC107 transistor inn front a IGBT transistor (IRG4BC30U), which runs the motor.My problem is that only 3 to 4V gets to the motor, and the IGBT will not let more than 2-3A to flow through the device. (I need 6-7A). My power supply is big enough, and the motor runs fine without the IGBT (straight on the supply)... I have also tried a MOSFET BUZ10, but that don't change anything worth mentioning.. The motor don't run on max, and the transistor gets extremely hot.What can I do to drive this motor as I please ?Is it normal that MOSFET and IGBT transistors make this big voltage drop when it's on? Quote Link to comment Share on other sites More sharing options...
indulis Posted May 25, 2007 Report Share Posted May 25, 2007 No they shouldn't get hot if they are driven properly.Could you provide a little more info...At what frequency are youu running?At what voltage are you driving the MOSFET?A schematic would help... exactly how is your circuit configured "after" the PIC?For 6-7A a MOSFET should work just fine. It's not to hard to find a MOSFET with a Rds on in the 10 milliohm range. If you do the math (I^2*R) for 100% duty cycle, that's only .49W @ 7A. The current you would need to drive it would depend on the switching frequency. Quote Link to comment Share on other sites More sharing options...
Tanna Posted May 25, 2007 Author Report Share Posted May 25, 2007 aaa... Found the problem.. I had placed det motor between the emitter and GND. Makes bad feedback for the workpoint of the transistor..When I placed the motor between the collector and +9.4V it works fine...Anyway.. Thank you... Quote Link to comment Share on other sites More sharing options...
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