What is the purpose of using dynamic braking resistors on a servo amplifier?

The purpose of using dynamic braking resistors on a servo amplifier is to dissipate the energy generated when a servo motor decelerates or is forced to rotate by an external load, preventing overvoltage on the DC bus of the amplifier. When a servo motor decelerates, it acts as a generator, converting kinetic energy back into electrical energy. This energy is fed back into the servo amplifier, increasing the voltage on the DC bus, which powers the amplifier's output stage. If the voltage on the DC bus exceeds a certain limit, it can damage the amplifier's components. Dynamic braking resistors provide a path for this regenerative energy to be safely dissipated as heat, preventing the DC bus voltage from rising to dangerous levels. For example, if a robot arm is rapidly lowered with a heavy load, the servo motor controlling the arm will generate a significant amount of regenerative energy. Without dynamic braking resistors, this energy could cause the DC bus voltage to rise excessively, potentially damaging the servo amplifier. The resistors are switched into the circuit by the servo amplifier when the DC bus voltage approaches its upper limit. The size and power rating of the dynamic braking resistors are chosen to handle the expected amount of regenerative energy for the specific application. This prevents overvoltage faults and ensures the reliable operation of the servo system.