YASKAWA SGM7J-A5A, Technical Supplement

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Appendices
582
Capacity Selection for Regenerative Resistors
If the regenerative power exceeds the amount that can be absorbed by charging the smoothing capacitor,
a regenerative resistor is used.
Regenerative Power and Regenerative Resistance
The rotational energy of a driven machine such as a Servo Motor that is returned to the SERVOPACK is
called regenerative power. The regenerative power is absorbed by charging a smoothing capacitor. When
the regenerative power exceeds the capacity of the capacitor, it is consumed by a regenerative resistor.
(This is called resistance regeneration.)
The Servo Motor is driven in a regeneration state in the following circumstances:
•
While decelerating to a stop during acceleration/deceleration operation.
•
While performing continuous downward operation on a vertical axis.
• During continuous operation in which the Servo Motor is rotated by the load (i.e., a negative load).
Types of Regenerative Resistors
The following regenerative resistors can be used.
• Built-in regenerative resistor: A regenerative resistor that is built into the SERVOPACK. Not all SERVO-
PACKs have built-in regenerative resistors.
• External Regenerative Resistor: A regenerative resistor that is connected externally to a SERVOPACK.
These resistors are used when the smoothing capacitor and built-in regenerative resistor in the
SERVOPACK cannot consume all of the regenerative power.
*1. Refer to the following section for the specifications of the regenerative resistors built into SERVOPACKs.
Built-In Regenerative Resistor (page 565)
*2. An optional external Regenerative Resistor Unit is required.
You cannot use the resistance regeneration provided by the SERVOPACK for continuous regener-
ation. For continuous operation with a negative load, you must design a system that also includes
a Power Regenerative Converter or Power Regenerative Unit (for example, Yaskawa model
D1000 or R1000). If regenerative power is not appropriately processed, the regenerative energy
from the load will exceed the allowable range and damage the SERVOPACK.
Examples of negative loads are shown below.
SERVOPACK Model Built-In Regenerative Resistor External Regenerative Resistor
SGD7S-
R70A, R90A, 1R6A, 2R8A None Basically not required
3R8A, 5R5A, 7R6A,
120A, 180A, 200A, 330A
Standard feature
*1 Basically not required
470A, 550A, 590A, 780A None
Required
*2
SGD7W- 1R6A, 2R8A, 5R5A, 7R6A Standard feature *1 Basically not required
Important
• Motor Drive to Lower Objects without a Counterweight • Motor Drive for Feeding
Tension
Servo Motor
Servo Motor
Servo Motor
Negative load that feeds a material at
a constant speed under tension