I have been dealing with l298 and mosfet driver lately and something happen which i do not understand.
MOSFETs that i am using are ifr9510 for upper bridge and irfz34 for lower bridge(all four are heat sink eqipped). I know the irf9510 commonly is paired with irf510. Since only irfz34 available to me, i used it for testing. My question is whether this kind of pairing will generated lots of heat. I could smell something if i put my nose nearer( not burn smell) and the driver is working(even can control the speed of the motor). However, i dare not to drive the motor too long. the MOSFETs are isolated by optocouplers 4n35. I'm not sure if this has anything to do with the overheating but i remember someone said that optocoupler cannot support the high speed of the PWM.
For l298, i am getting a insensitive speed control. l298 is controlled by PIC16F877a. the speed is set at range of 0 - 128(0 for 0% duty cycle and 128 for 100% duty cycle).
Direction = anticlockwise
Max speed = 0
Min speed = 128
Direction = clockwise
Max speed = 128
Min speed = 0
Above are results i suppose to get but what i got are:
Direction = anticlockwise
Max speed = 0
Min speed = around 30 - 40 ( >40 the motor completely off)
Direction = clockwise
Max speed = around 30 - 40 (>40 motor complety on / full speed)
Min speed = 0
i know it's hard without schematic but i'm in rush now. I'll post the schematic later. Hopefully, anyone can provide me some advices and assistance in the mean time. TQ
Eric