I'm working with a brushed DC motor rated for 12V and 250W, but I've noticed it can pull over 100A when stalled. To manage the current draw, I'm considering driving it with about 28V, and I want to make sure I can monitor and limit the motor's power and RPM. My concern is whether this might negatively impact the motor's lifespan, especially in terms of arcing at the brushes. Any insights on this would be greatly appreciated!
4 Answers
Running your motor at a higher voltage with PWM is generally safe. That's a common technique in many industrial applications. I once set up a 48V system for 12V bilge pump motors in an underwater robot years back, and those motors are still going strong after 15 years!
Make sure to carefully monitor the motor for any signs of overheating as you implement the new voltage levels. It could impact how long your motor lasts.
If you pump up the voltage, the motor will definitely spin faster and could pull more current. How exactly are you planning to limit the current? Most of the time, current limiting is achieved through reducing the voltage in a feedback loop.
If you double the voltage and set your PWM duty cycle to 50%, the motor should run at the same RPM but with half the average current.
Are you planning to keep an eye on the motor's temperature? You might see some advantages with the 28V and 50% duty cycle setup, especially if you incorporate feedback from an optical tach and a thermistor. I'd love to hear about your build results later!
I'm thinking of using PWM with a closed-loop feedback system.