While electric motors "consume" energy during acceleration and continuous movement they tend to generate energy during fast deceleration or electric braking. With typical driver circuits this energy coming from the motor is fed back into supply rail. Depending on amount of energy supply voltage might increase up-to critical levels for driver electronics and other connected electronic circuits.
This is a common problem with applications requiring highly dynamics movements or where the motor is moved by external force. As long as the amount of energy is rather small adding capacitors between positive and negative supply and adding suppressor diodes with suitable voltage ratings will help and be sufficient. Beyond that dedicated brake chopper circuits with power resistors are used in order to convert the surplus energy into heat.
Some Trinamic devices, such as the TMCM-3314, have a brake chopper circuit on board and ready to use. All that is needed is to connect a brake resistor.
So how is this brake resistor sized?
So how is this brake resistor sized?
In order to properly size a brake resistor, you need to know a bit about the system conditions.
1. What is the voltage supply being used? Let's call this "V_supply".
2. How much power is being generated during the fast deceleration or from rotation by external forces? Let's call this "P_brake".
Now, the maximum current through the brake resistor can be calculated:
I_brake = P_brake / V_supply
Now we can calculate the required resistance as:
R_brake = V_Supply / I_brake.
Your brake resistor, therefore, needs to have a value of at least R_brake Ohms and the resistor must be rated for for P_brake Watts