Hi Naeem,
I see your becoming a pro on rewinding , very nice job
what do you think is the over all milage on that motor.
I have dug out my long hidden cct. bread board and some electronic components so that i can build the 555 timer cct. you have. Just to show you were to improve the cct.
The following is scope pictures is defined in sequence
1.) breadboard setup
2.) Gate pulse at zero throttle
3.) Gate pulse at 50 percent throttle
4.) Gate pulse at 100 percent throttle
5.) main supply input with capacitor filter
6.) main supply input without capacitor filter
First i recalculate your cct. frequency and it around 300hz which is ok in this application.
1.)Just to show you that your motor is not totally off at zero throttle, picture 2 is the gate pulse of the fet at zero throttle, which means the motor is on but don't have enough current to turn it over. This will drain your battery a bit and heat up the mosfets no big deal while seating in traffic jam but big deal if you park the bike for a long time. If you want to improve this you can take pin #4 of the 555 timer which is now wired to the 12v supply. Cut the 12v supply off, then wire a switch of any kind big or small doesn't matter from pin#4 to ground. This will give you the on/off for the controller. But its still a good practice to unplug main power from the controller when the bike is park and lock up.
2.) picture 3 and 4 is just for comparison to picture 2
3.) Picture 5, this is what it looks like with a big capacitor in the input supply of 48V to ground, the small spike you see is cause by the back emf of the motor while at zero throttle, the big capacitor cannot totally filter it but this is ok because the top of the ring is with in the supply voltage.
4.) Picture 6, this is what it looks like without a big capacitor in the input supply of 48V to ground, this is something you don't want in the cct., the spike voltage is almost equal to the supply voltage. Which means that during riding the spike voltage + the supply voltage can add up over 100v
no good. It will degrade your fets and blow.
P.S when you parallel a capacitor the capacitance gets larger, when you series a capacitor the capacitance get smaller.
formula for parallel Ctotal = C1+C2+C3+C4+C5+ etc.
The capacitor that has a + and - sign is called a polarized capacitor, this can only be hooked up + to + and - to - if hooked up backward in the supply section electrolytic and tantalum type will blow up like a fire cracker and makes a big mess. Also you cannot exceed the the voltage rating of the capacitor or it will blow up as will.
Tricks with the polarized capacitor,
- you can hooked up two capacitor either way - to - or + to + in series and it becomes none polarized , the two leg remain can be hooked up either way in the supply voltage, other benefit is that the two voltage rating in the capacitor adds up together.
Example: 35v capacitor tied in series to a 50v will become 85v in total, but capacitance gets less is series here's the formula for series 1/Ctotal = 1/C1 + 1/C2 + 1/C3 + 1/C4 etc.
Zenon
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