I was reading through a document from the web and noticed two paragraphs saying:
“There is a special consideration if the power supply voltage will be at or near the maximum
voltage rating of the drive. If the motor will be rapidly decelerating a large inertial load from a high
speed, care has to be taken to absorb the returned energy. The energy stored in the momentum
of the load must be removed during deceleration and be safely dissipated. Because of its
efficiency, the drive has no means of dissipating this energy so it returns it to the power supply. In
effect, instead of drawing current from the power supply, the drive becomes a source of current
itself. This current then may charge the power supply capacitor to destructive voltage levels.
If more than one drive is operating from the power supply this is not a problem since the other
drive will absorb this current for its needs, unless of course it is decelerating as well. For this case
or for a single drive it may be necessary to place a voltage clamp across the power supply in the
form of a zener diode. The voltage of this diode must be greater than the maximum expected
power supply voltage, yet low enough to protect the drive. A good choice would be either 82 volts
or 91 volts as standard values.”
Based on the above two paragraphs, I don’t want to sound like an expert or go against this forum’s knowledgeable people but I would like to know if we have sized the capacitors big enough to accept the motors deceleration energy or if I should install a voltage clamp across the power supply.