H_Bridge Motor Driver or how to control my DC motors
December 13, 2011
Dear, Mates !
For less than ten days i suffer for second time trying to construct my own HBridge so probably i really need somebody helps me, please.
The last time i bought the set i thought everything whould be fine :
- 4 Transistors (2xIRF640 and 2xIRF9540n) and two resistors(8K,0.25) this should be the most basic things to build an HBridge ?
I am not really sure as i've been 30 minutes ago, but the most important parameters i had to suppose was
-For IRF640 VDSS 100 V ID 22 A
-For IRF9540N VDSS -100 V ID -22 A
( I chose them because i am expecting to turn a motor with 30V and 4A consumption. )
and VGS(th) for both transistors 2 to 4 Volts - perfect for my parallel port.
If you haven't corrected me yet please don't be ashame, but isn't VGS(th) the trigger and the Only requirement on Gate to turn transistors working ?
I don't know where do i make mistake so, please look at the diagram above.
As i see when in initial position OUT A and OUT B are 0V so PChannels are passing, but NChannels do not and as result noting happens.
If i set OUT A to 5V left PChannel stops passing, right P is passing and left N is passing so motor is working.
If i set OUT B, motors spins opossite.
If all this is fine with you i would like to ask if the problem is wrong pin mapping? Both P and N Channel Mosfets are Gate,Drain,Source oriented when look at in front (they have an equal mapping)
Any help for how HBridge works would be highly appreciated !
The reason i need to know it is becouse i want to call myself one day a robot builder as you do !
Thank you again !