Kinetic energy is stored by the total moment of inertia or mass and the commanded (and achieved) axis velocity. Assuming no potential energy sources, energy used to accelerate an axis to its commanded velocity is supplied by the servo drive’s power source.
Fusing and the wiring of both single and multi-axis systems are reviewed. The paper concludes with a worked example. During normal operation, the servo drive receives electrical power from a DC bus supply and outputs a controlled electrical power through the phases of the motor.
Use the servo drive’s regeneration circuit to dissipate the excess DC-bus energy across a regeneration (regen) power resistor. This is an often-used solution. A regen resistor is a resistive-power device used to dissipate the pumped-up DC-bus energy — to dissipate the excess.
If the bus voltage increases too much, the power transistor rating can be exceeded causing component failure. A shunt braking resistor can be connected to the servo drive to dissipate this excess of regenerated energy, preventing potentially damaging voltage levels.
When wiring multiple drives in parallel to the same power supply or battery, a single shunt resistor could be shared among all the axes. Do this only if the braking current of all the axes does not exceed each individual servo drive’s shunt current capacity. Paralleling the shunt output is possible as the drives have an open drain output.
The drawback with this method is how it can add significant cost and size to the drive system electronics. Use the servo drive’s regeneration circuit to dissipate the excess DC-bus energy across a regeneration (regen) power resistor. This is an often-used solution.