Hi, I'm new to this forum and I had read a few threads in this forum. Also, I'm quite new to building electronic circuits eventhough I'm studying electronics -.-. My college doesn't give us many projects.

I'm trying to build a motor driver/controller and I read that PWM is a good way to control the speed of motors. I saw some circuit diagrams online but I don't really understand most of them. There are some simple circuits and some complicated ones and I'm not sure which to use.

I'm currently building a 3-wheel human transporter for my project and I'm using a 12V 40A lead acid battery. I've used a controller from a golf trolley and it worked fine but I figured since it's my project, it's better for me to build one. I saw a person doing something similar using this circuit:
http://www.dprg.org/tutorials/2005-11a/2005-10a-004.gif
a suggestion said that to parallel another 1 or 2 mosfets. I'm not sure whether it works and judging by the components, I'm not sure whether the other components, other than the mosfet, can withstand the power when the motor draws a high current to push a heavy load.

Please help me out here, thanks

 

PWM is definitely a proven way to control DC motor speed. You might check this out: http://store.qkits.com/moreinfo.cfm/MXA06, if you can get by using a module. If you HAVE to build the unit yourself, you could get this module and put the components on your own PC board (no, it's not cheating, it's called working smarter). You would have to know about etching PCBs OR point-to-point wiring, but this would be MUCH simpler than building one from scratch. I don't know if this is a kit or a completed module, but if it is a kit it would be easier since you would not have to remove the components. If it is a completed module, I wouldn't "transplant" the resistors and capacitors to your new board--just put new ones on your new board; but the IC, the output MOSFETS, other semiconductors, and that heat sink would have to be carefully removed and put on your homemade board. You would, of course, have to reverse-engineer this unit so you have the circuit traces 100% correct so your etches or point-to-point wiring will be accurate. Sorry, but you are dealing with a slightly complex project here and will need some basic skills (soldering, board fabrication, wiring, etc. Make sure your wiring to the battery and motor is all large gauge wire or you will not get far. Maybe someone else will have an easier solution.

 

lol thing is, I live in Malaysia. I can't afford that kit, it's way too expensive. That's why I need to build one. Thanks for your info.

 

This circuit will work and will be able to handle the motor's current if you choose the appropriate MOSFET. One thing he missed is a diode in anti-parallel with the motor as to absorb the back EMF when switching the motor off.

If you want to add more controls such as speed feedback it will be better to use a microcontroller.

 

check out this thread about H-Bridges and PWM control of DC Motors up to 50VDC

http://forum.allaboutcircuits.com/showthread.php?t=28454

 

alright. thanks for the advices. i'll try both circuits to see how it'll work on my motor. really thanks a lot guys.