Reducing DC motor starting current


I was wondering is there a way to reduce the DC motor current draw from starting? For example, I have a motor with a 40A starting current but power electronics that deliver 5A continuous and 10A max current, and i don’t want to kill it when I turn on the robot.


Hello, Mike.

One way you can limit the current a motor draws when starting from rest is to slowly ramp up the speed instead of immediately applying a 100% duty cycle voltage. However, it might be a good idea to consider switching to a more powerful motor driver or controller, especially if there is some chance that your motor might ever stall or be subjected to enough of a load to exceed the capability of your electronics.

- Kevin

Thanks! Do you have an intuitive sense of what will happen if I use a standard motor driver in this case? Will it simply max out at 10A, or will it overdrive to above 10A and trip something internal or simply burn out the driver?

It depends on the particular driver you are using. Some will just burn out, while others might have built-in overcurrent or overtemperature protection that could stop the motor temporarily or indefinitely and prevent the driver from being damaged. However, we generally do not recommend relying on this type of fault detection to limit motor current during routine use.

- Kevin