# Is it possible to decrease the power dissipated in a winding with a constant braking torque?

I have a 4-quadrant current controller which regulates the braking current of a brushed DC motor with a high-inertia load to a constant level, but the motor winding cannot handle the current required to halt the load in the time I want.

I thought I could dissipate the energy elsewhere by regulating the braking current and letting it drain back into the supply where a DC link regulator is, but I was wrong: the only thing I would be doing, would be to charge up the inductor, and discharge it into the DC link regulator.

I have the feeling now that I can't decrease the power the winding itself dissipates for a given mechanical braking power, since I can clearly see the mechanical breaking power is the back-EMF (constant at a given time) times the current (constant because regulated at the desired braking torque), regardless of what I do with the current.

Could anyone confirm or suggest how I could achieve what I want electrically (except brake over a longer time)?

• If your motor can't do it then you're looking for a friction or magnetic brake, I suspect. Nov 19, 2020 at 21:00
• The shaft torque and the winding current are related. Just as you cannot accelerate an inertial load too quickly without overloading the windings, you cannot decelerate that load too quickly without overloading the windings. As you have noted, you can decrease the current by braking over a longer time. If your windings are overheating, there is not much else you can do. Nov 19, 2020 at 21:04
• You can't change the current, and you can't change the winding resistance, and the power is the current times the resistance squared, so... Nov 19, 2020 at 21:07
• Perhaps you can blow a fan on it or something? Nov 19, 2020 at 21:07
• You CAN reduce power in the winding by dissipating power in a braking resistor. However this inevitably reduces the braking current (compared to shorting the winding); braking torque is thus also reduced and braking time is increased.
– user16324
Nov 19, 2020 at 21:08