a new project at my power electronic lab says:
"make an electronic control circuit for the turns of a motor DC current with working voltage 0-12V DC,maximum power 500W, trigger Voltage 12V and trigger current 3A"
any suggestions?????

 

use a current based op-amp

 

you can use a pwm to control the speed of your motor... if the current is too low, use an h-bridge.

 

Well in the spec of the motor he mentioned 500W - it's going to need a good sized H-bridge :lol:

This sounds like the size of things used in the smaller Robot Wars machines, most of those use 4QD controllers and similar. There's an example circuit at http://www.4qdtec.com/pwm-01.html.

 

PWM is the way to go. At 12 V you need to drive 41A to get the 500W spec. You'd be hard pressed to make a linear amp that can provide that kind of power. A simple N-Channel mosfet as a low side driver should work. You might have to parallel a couple Mosfets to get the current capability to 41V (You might have to do a little reasearch to make this work right). Make sure you use a MOSFET Driver to turn tham on and off quickly. You only need an H-bridge if you need to control the direction of spin- if one direction is enough dont worry about the bridge.

Hope this helps
Brent